] Shares(1) OPTIMER PHARMACEUTICALS, INC. Common Stock PURCHASE AGREEMENT

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Exhibit 1.1

[ ] Shares(1)

OPTIMER PHARMACEUTICALS, INC.

Common Stock

PURCHASE AGREEMENT

[ ], 2007

▇▇▇▇▇ ▇▇▇▇▇▇▇ & CO.
▇▇▇▇▇▇▇▇▇ & COMPANY, INC.
As Representatives of the several
Underwriters named in Schedule I hereto

c/o ▇▇▇▇▇ ▇▇▇▇▇▇▇ & Company, Inc.
▇▇▇ ▇▇▇▇▇▇▇▇ ▇▇▇▇
▇▇▇▇▇▇▇▇▇▇▇, ▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇

c/▇ ▇▇▇▇▇▇▇▇▇ & Company, Inc.
▇▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇
▇▇▇ ▇▇▇▇, ▇▇▇ ▇▇▇▇ ▇▇▇▇▇

Ladies and Gentlemen:

Optimer Pharmaceuticals, Inc., a Delaware corporation (the "Company") proposes, subject to the terms and conditions stated herein, to sell to the several Underwriters named in Schedule I hereto (the "Underwriters") an aggregate of [ ] shares (the "Firm Shares") of Common Stock, $0.001 par value per share (the "Common Stock"), of the Company. The Firm Shares consist of [ ] authorized but unissued shares of Common Stock to be issued and sold by the Company.

The stockholders of the Company listed in Schedule II hereto (the "Selling Stockholders") propose to sell to the Underwriters, at the election of the Underwriters, up to [ ] additional shares of Common Stock on the terms and for the purposes set forth in Section 3 hereof (the "Option Shares"). The Firm Shares and any Option Shares purchased pursuant to this Purchase Agreement are herein collectively called the "Securities." ▇▇▇▇▇ ▇▇▇▇▇▇▇ & Co. and ▇▇▇▇▇▇▇▇▇ & Company, Inc. are acting as lead managers (the "Lead Managers") in connection with the offering and sale of the Securities contemplated herein.

The Company also proposes, subject to the terms of this Agreement, the applicable rules, regulations and interpretations of the NASD (as defined below) and all other Applicable Laws, rules and regulations, that up to 5% of the Firm Shares shall be reserved for sale by the Underwriters to certain officers, directors, employees and other persons designated by the Company.

The Company and the Selling Stockholders hereby confirm their agreement with respect to the sale of the Securities to the several Underwriters, for whom you are acting as representatives (the "Representatives").

(1): Plus an option to purchase up to [ ] additional shares to cover over-allotments.

1. Registration Statement and Prospectus. A registration statement on Form S-1 (File No. 333-138555) with respect to the Securities, including a preliminary form of prospectus, has been prepared by the Company in conformity with the requirements of the Securities Act of 1933, as amended (the "Act"), and the rules and regulations ("Rules and Regulations") of the Securities and Exchange Commission (the "Commission") thereunder and has been filed with the Commission; one or more amendments to such registration statement have also been so prepared and have been, or will be, so filed; and, if the Company has elected to rely upon Rule 462(b) of the Rules and Regulations ("Rule 462(b)") to increase the size of the offering registered under the Act, the Company will prepare and file with the Commission a registration statement with respect to such increase pursuant to Rule 462(b). Copies of such registration statement(s) and amendments and each related preliminary prospectus have been delivered to you.

If the Company has elected not to rely upon Rule 430A of the Rules and Regulations ("Rule 430A"), the Company has prepared and will promptly file an amendment to the registration statement and an amended prospectus. If the Company has elected to rely upon Rule 430A, it will prepare and file a prospectus pursuant to Rule 424(b) of the Rules and Regulations ("Rule 424(b)") that discloses the information previously omitted from the prospectus in reliance upon Rule 430A. Each part of such registration statement as amended at the time it is or was declared effective by the Commission, and, in the event of any amendment thereto after the effective date, each part of such registration statement as so amended (but only from and after the effectiveness of such amendment or, the date it is first used after effectiveness of the registration statement, in the case of information contained in a form of prospectus filed with the Commission pursuant to Rule 424(b) and deemed to be part of the registration statement pursuant to Rule 430C of the Rules and Regulations ("Rule 430C")), including a registration statement (if any) filed pursuant to Rule 462(b) increasing the size of the offering registered under the Act, information (if any) deemed to be part of the registration statement at the time of effectiveness pursuant to Rule 430A(b) and information (if any) contained in a form of prospectus required to be filed with the Commission pursuant to Rule 424(b) and deemed to be part of and included in the registration statement on the date it is first used after effectiveness in accordance with Rule 430C, is hereinafter called the "Registration Statement." The prospectus included in the Registration Statement at the time it is or was declared effective by the Commission is hereinafter called the "Prospectus," except that if any prospectus filed by the Company with the Commission pursuant to Rule 424(b) or any other such prospectus provided to the Underwriters by the Company for use in connection with the offering of the Securities (whether or not required to be filed by the Company with the Commission pursuant to Rule 424(b), but not including a "free writing prospectus" as defined in Rule 405 of the Rules and Regulations ("Rule 405")) differs from the prospectus on file at the time the Registration Statement is or was declared effective by the Commission, the term "Prospectus" shall refer to such differing prospectus from and after the time such prospectus is filed with the Commission or transmitted to the Commission for filing pursuant to such Rule 424(b) or from and after the time of its first use within the meaning of the Rules and Regulations. The term "Preliminary Prospectus" as used herein means any preliminary prospectus included in the Registration Statement prior to the time it becomes or became effective under the Act and any prospectus subject to completion as described in Rule 430A. Any reference herein to any Preliminary Prospectus or the Prospectus shall be deemed to refer to and include any wrapper or supplement thereto prepared in connection with the distribution of the Directed Stock (as defined below) in any jurisdiction. All references in this Agreement to the Registration Statement, any Preliminary Prospectus, the Prospectus or any amendment or supplement to any of the foregoing, shall be deemed to include the copy filed with the Commission pursuant to its Electronic Data Gathering, Analysis and Retrieval System ("▇▇▇▇▇").

2. Representations and Warranties of the Company and the Selling Stockholders.

(a) The Company represents and warrants to, and agrees with, the several Underwriters as follows:

(i) No order preventing or suspending the use of any Preliminary Prospectus or any Issuer Free Writing Prospectus (as defined below) has been issued by the Commission and each Preliminary Prospectus, at the time of filing thereof or the time of first use within the meaning of the Rules and Regulations, complied in all material respects with the requirements of the Securities Act and the Rules and Regulations and did not contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading; except that the foregoing shall not apply to statements in or omissions from any Preliminary Prospectus in reliance upon, and in conformity with, written information furnished to the Company by you, or by any Underwriter through you, specifically for use in the preparation thereof.

(ii) As of the time any part of the Registration Statement (or any post-effective amendment thereto, including a registration statement (if any) filed pursuant to Rule 462(b) increasing the size of the offering registered under the Act) became effective, upon the filing or first use within the meaning of the Rules and Regulations of the Prospectus (or any supplement to the Prospectus) and at the First Closing Date and Second Closing Date (as hereinafter defined), (A) the Registration Statement and the Prospectus (in each case, as so amended and/or supplemented) conformed or will conform in all material respects to the requirements of the Act and the Rules and Regulations, (B) the Registration Statement (as so amended) did not or will not include an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading, and (C) the Prospectus (as so supplemented) did not or will not include an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein, in light of the circumstances in which they are or were made, not misleading; except that the foregoing shall not apply to statements in or omissions from any such document in reliance upon, and in conformity with, written information furnished to the Company by you, or by any Underwriter through you, specifically for use in the preparation thereof. If the Registration Statement has been declared effective by the Commission, no stop order suspending the effectiveness of the Registration Statement has been issued, and no proceeding for that purpose has been initiated or, to the Company's knowledge, threatened by the Commission.

(iii) Neither (A) the Issuer General Free Writing Prospectus(es) issued at or prior to the Time of Sale and the Statutory Prospectus, all considered together (collectively, the "Time of Sale Disclosure Package"), nor (B) any individual Issuer Limited-Use Free Writing Prospectus, when considered together with the Time of Sale Disclosure Package, includes or included as of the Time of Sale any untrue statement of a material fact or omit or omitted as of the Time of Sale to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading. The preceding sentence does not apply to statements in or omissions from any Statutory Prospectus or any Issuer Free Writing Prospectus based upon and in conformity with written information furnished to the Company by you, or by any Underwriter through you, specifically for use therein. As used in this paragraph and elsewhere in this Agreement:

(1) "Time of Sale" means [ ]:00 [a.m./p.m.] (Eastern time) on the date of this Agreement.

(2) "Statutory Prospectus" as of any time means the prospectus that is included in the Registration Statement immediately prior to that time. For purposes of this definition, information contained in a form of prospectus that is deemed retroactively to be a part of the Registration Statement pursuant to Rule 430A shall be considered to be included in the Statutory Prospectus as of the actual time that form of prospectus is filed with the Commission pursuant to Rule 424(b).

(3) "Issuer Free Writing Prospectus" means any "issuer free writing prospectus," as defined in Rule 433 of the Rules and Regulations ("Rule 433"), relating to the Securities that (A) is required to be filed with the Commission by the Company, or (B) is exempt from filing pursuant to Rule 433(d)(5)(i) because it contains a description of the Securities or of the offering that does not reflect the final terms or pursuant to Rule 433(d)(8)(ii) because it is a "bona fide electronic road show," as defined in Rule 433 which is made available without restriction, in each case in the form filed or required to be filed with the Commission or, if not required to be filed, in the form retained in the Company's records pursuant to Rule 433(g).

(4) "Issuer General Free Writing Prospectus" means any Issuer Free Writing Prospectus that is intended for general distribution to prospective investors, as evidenced by its being specified in Schedule III to this Agreement.

(5) "Issuer Limited-Use Free Writing Prospectus" means any Issuer Free Writing Prospectus that is not an Issuer General Free Writing Prospectus. The term Issuer Limited-Use Free Writing Prospectus also includes any "bona fide electronic road show," as defined in Rule 433, that is made available without restriction pursuant to Rule 433(d)(8)(ii), even though it is not required to be filed with the Commission.

(iv) (A) Each Issuer Free Writing Prospectus, as of its issue date and at all subsequent times through the completion of the public offer and sale of the Securities or until any earlier date that the Company notified or notifies the Representatives as described in Section 4(a)(iii)(B), did not, does not and will not include any information that conflicted, conflicts or will conflict with the information contained in the Registration Statement, any Statutory Prospectus or the Prospectus. The foregoing sentence does not apply to statements in or omissions from any Issuer Free Writing Prospectus based upon and in conformity with written information furnished to the Company by you, or by any Underwriter through you, specifically for use therein.

(B) (1) At the time of filing the Registration Statement and (2) at the date hereof, the Company was not and is not an "ineligible issuer," as defined in Rule 405, including the Company or any subsidiary in the preceding three years not having been convicted of a felony or misdemeanor or having been made the subject of a judicial or administrative decree or order as described in Rule 405 (without taking account of any determination by the Commission pursuant to Rule 405 that it is not necessary that the Company be considered an ineligible issuer), nor an "excluded issuer" as defined in Rule 164 of the Rules and Regulations ("Rule 164").

(C) Each Issuer Free Writing Prospectus satisfied, as of its issue date and at all subsequent times through the completion of the public offer and sale of the Securities, all other conditions to use thereof as set forth in Rules 164 and 433 under the Act.

(v) The financial statements and pro forma data of the Company, together with the related notes, set forth in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus comply in all material respects with the requirements of the Act and fairly present the consolidated financial condition of the Company as of the dates indicated and the

results of operations and changes in cash flows for the periods therein specified in conformity with generally accepted accounting principles in the United States consistently applied throughout the periods involved; and the supporting schedules included in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus have been derived from the accounting records of the Company and present fairly the information required to be stated therein. No other financial statements or schedules are required to be included in the Registration Statement, the Time of Sale Disclosure Package or the Prospectus. Ernst & Young LLP, which has expressed its opinion with respect to the financial statements and schedules filed as a part of the Registration Statement and included in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus, is (X) an independent public accounting firm within the meaning of the Act and the Rules and Regulations, (Y) a registered public accounting firm (as defined in Section 2(a)(12) of the ▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act of 2002 (the "▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act")) and (Z) in the performance of their work for the Company, not in violation of the auditor independence requirements of the ▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act. Except as disclosed in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus, there are no material off-balance sheet transactions, arrangements, obligations (including contingent obligations), or any other relationships with unconsolidated entities or other persons, that may have a material current or, to the Company's knowledge, future effect on the Company's financial condition, results of operations, liquidity, capital expenditures, capital resources or significant components of revenue or expenses. The other financial and statistical information included in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus present fairly the information included therein and have been prepared on a basis consistent with that of the financial statements that are included in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus and the books and records of the respective entities presented therein. No person who has been suspended or barred from being associated with a registered public accounting firm, or who has failed to comply with any sanction pursuant to Rule 5300 promulgated by the Public Company Accounting Oversight Board, has participated in or otherwise aided the preparation of, or audited, the financial statements, supporting schedules or other financial data included in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus.

(vi) The Company and each of its subsidiaries has been duly organized and is in good standing under the laws of the state of its jurisdiction. The Company is validly existing as a corporation, and each of its subsidiaries is also validly existing. Each of the Company and its subsidiaries has full corporate power and authority to own its properties and conduct its business as currently being carried on and as described in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus, and is duly qualified to do business as a foreign corporation in good standing in each jurisdiction in which it owns or leases real property or in which the conduct of its business makes such qualification necessary and in which the failure to so qualify would have a material adverse effect upon, or change in, (A) the general affairs, business, prospects, properties, operations, condition (financial or otherwise) or results of operations, whether or not arising from transactions in the ordinary course of business, of the Company and its subsidiaries or (B) the ability of the Company to consummate the transactions contemplated herein or by the Time of Sale Disclosure Package ("Material Adverse Effect" or "Material Adverse Change").

(vii) Except as set forth in the Time of Sale Disclosure Package and the Prospectus, the Company does not, directly or indirectly, own or control any capital stock or other equity ownership or proprietary interest in any corporation, partnership, association, trust or other entity. The Company is not a participant in any joint venture, partnership or similar arrangement.

(viii) Except as contemplated in the Time of Sale Disclosure Package and in the Prospectus, subsequent to the respective dates as of which information is given in the Time of Sale Disclosure Package and the Prospectus, the Company has not incurred any material liabilities or obligations, direct or contingent, or entered into any material transactions, including any acquisition or disposition of any business or asset, or declared or paid any dividends or made any distribution of any kind with respect to its capital stock; there has not been any change in the capital stock (other than a change in the number of outstanding shares of Common Stock due to the issuance of shares upon the exercise of outstanding options or warrants), or any material change in the short-term or long-term debt, or any issuance of options, warrants, convertible securities or other rights to purchase the capital stock, of the Company or any Material Adverse Change or any development that could reasonably be expected to result in a Material Adverse Change; and the Company has not sustained any material loss or interference with its business or properties from fire, explosion, flood, hurricane, accident or other calamity, whether or not covered by insurance, or from any labor dispute or any legal or governmental proceeding.

(ix) Except as set forth in the Time of Sale Disclosure Package and in the Prospectus, there is not pending or, to the knowledge of the Company, threatened, any action, suit or proceeding to which the Company or any subsidiary is a party or of which any property or assets of the Company or any subsidiary is the subject before or by any court or Governmental Authority (as defined below), or any arbitrator, which, individually or in the aggregate, might result in any Material Adverse Change and the defense of all such proceedings, litigation and arbitration against or involving the Company could not reasonably be expected to have a Material Adverse Effect. There are no current or pending legal, governmental or regulatory actions, suits or proceedings to which the Company or any subsidiary is a party of which any property or assets of the Company or any subsidiary is subject that are required to be described in the Registration Statement, Time of Sale Disclosure Package and Prospectus by the Act or by the Rules and Regulations that have not been so described.

(x) There are no statutes, regulations, contracts or documents that are required to be described in the Registration Statement, in the Time of Sale Disclosure Package and in the Prospectus or be filed as exhibits to the Registration Statement by the Act or by the Rules and Regulations that have not been so described or filed.

(xi) This Agreement has been duly authorized, executed and delivered by the Company, and constitutes a valid, legal and binding obligation of the Company, enforceable in accordance with its terms, except as rights to indemnity hereunder may be limited by federal or state securities laws and except as such enforceability may be limited by bankruptcy, insolvency, reorganization or similar laws affecting the rights of creditors generally and subject to general principles of equity. The execution, delivery and performance of this Agreement and the consummation of the transactions herein contemplated will not (A) conflict with or result in a breach or violation of any of the terms or provisions of, or constitute a default under, or result in the creation or imposition of any lien, charge or encumbrance upon any property or assets of the Company or pursuant to any indenture, mortgage, deed of trust, loan agreement or other agreement or instrument to which the Company is a party or by which the Company is bound or to which any of the property or assets of the Company is subject which would be reasonably likely to have a Material Adverse Effect, (B) result in any violation of the provisions of the charter, by-laws or other organizational documents of the Company or (C) result in the violation of any law or statute or any judgment, order, rule, regulation or decree of any court or arbitrator or federal, state, local or foreign governmental agency or regulatory authority having jurisdiction over the properties or assets of the Company (each, a

"Governmental Authority") which would be reasonably likely to have a Material Adverse Effect. No consent, approval, authorization or order of, or filing with, any court or Governmental Authority is required for the execution, delivery and performance of this Agreement or for the consummation of the transactions contemplated hereby, including the issuance or sale of the Securities by the Company, except such as may be required under the Act or state securities or blue sky laws and such as have been obtained under the laws and regulations of jurisdictions outside the United States in which Directed Stock is offered; and the Company has full power and authority to enter into this Agreement and to consummate the transactions contemplated hereby, including the authorization, issuance and sale of the Securities as contemplated by this Agreement.

(xii) All of the issued and outstanding shares of capital stock of the Company, including the outstanding shares of Common Stock, are duly authorized and validly issued, fully paid and nonassessable, have been issued in compliance with all federal and state securities laws, were not issued in violation of or subject to any preemptive rights or other rights to subscribe for or purchase securities that have not been waived in writing (a copy of which has been delivered to counsel to the Representatives), and the holders thereof are not subject to personal liability solely by reason of being such holders; the Securities which may be sold hereunder by the Company have been duly authorized and, when issued, delivered and paid for in accordance with the terms of this Agreement, will have been validly issued and will be fully paid and nonassessable, will have been issued in compliance with all applicable state, federal and foreign securities laws and the holders thereof will not be subject to personal liability solely by reason of being such holders; and the capital stock of the Company, including the Common Stock, conforms to the description thereof in the Registration Statement, in the Time of Sale Disclosure Package and in the Prospectus. Except as otherwise stated in the Registration Statement, in the Time of Sale Disclosure Package and in the Prospectus, there are no preemptive rights or other rights to subscribe for or to purchase, or any restriction upon the voting or transfer of, any shares of Common Stock pursuant to the Company's charter, by-laws or any agreement or other instrument to which the Company is a party or by which the Company is bound. Neither the filing of the Registration Statement nor the offering or sale of the Securities as contemplated by this Agreement gives rise to any rights for or relating to the registration of any shares of Common Stock or other securities of the Company, except for such rights as have been duly waived. All of the issued and outstanding shares of capital stock of each of the Company's subsidiaries have been duly and validly authorized and issued and are fully paid and nonassessable, and, except as otherwise described in the Registration Statement, in the Time of Sale Disclosure Package and in the Prospectus, the Company owns of record and beneficially, free and clear of any security interests, claims, liens, proxies, equities or other encumbrances, all of the issued and outstanding shares of such stock. Except as described in the Registration Statement, in the Time of Sale Disclosure Package and in the Prospectus, there are no options, warrants, agreements, contracts or other rights in existence to purchase or acquire from the Company or any subsidiary of the Company any shares of the capital stock of the Company or any subsidiary of the Company. The Company has an authorized and outstanding capitalization as set forth in the Registration Statement, in the Time of Sale Disclosure Package and in the Prospectus. The description of the Company's stock option, stock bonus and other stock plans or arrangements and the options or other rights granted thereunder, set forth in the Registration Statement, in the Time of Sale Disclosure Package and in the Prospectus accurately and fairly presents the information required to be shown with respect to such plans, arrangements, options and rights.

(xiii) The Company and each of its subsidiaries possesses all requisite power and authority, and all licenses, consents, certificates, permits and other authorizations issued by, and have

made all declarations and filings with, the appropriate Governmental Authorities that are necessary for the ownership, lease or operation of their properties or the conduct of their businesses as now being conducted and as described in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus, except where failure to do so would not be reasonably likely to have a Material Adverse Effect; neither the Company nor its subsidiaries have received notice of any revocation or modification of any such license, consent, certificate, permit or authorization and have not received notice that any such license, consent, certificate, permit or authorization will not be renewed in the ordinary course, the loss of which would be reasonably likely to have a Material Adverse Effect, and the Company and its subsidiaries are in compliance in all material respects with all applicable federal, state, local and foreign laws, regulations, orders and decrees.

(xiv) The Company and its subsidiaries own or lease all such properties as are reasonably necessary to the conduct of their businesses as presently operated as described in the Time of Sale Disclosure Package and the Prospectus. The Company and its subsidiaries have good and marketable title in fee simple to all property (whether real or personal) described in the Registration Statement, in the Time of Sale Disclosure Package and in the Prospectus as being owned by them, and individually or in the aggregate, material to the Company's business, in each case free and clear of all liens, claims, security interests, other encumbrances or defects except such as are described in the Registration Statement, in the Time of Sale Disclosure Package and in the Prospectus. The property held under lease by the Company and its subsidiaries is held by them under valid, subsisting and enforceable leases with only such exceptions with respect to any particular lease as do not interfere in any material respect with the conduct of the business of the Company and its subsidiaries. Neither the Company nor its subsidiaries has received any notice of any material claim adverse to its ownership of any real or personal property or of any material claim against the continued possession of any real property, whether owned or held under lease or sublease of the Company or its subsidiaries.

(xv) Except as described in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus, the Company and each of its subsidiaries own, possess or can acquire on reasonable terms all Intellectual Property (as defined below) reasonably necessary for the conduct of the business of the Company and its subsidiaries as described in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus as now conducted or to be conducted, except to the extent such failure to own, possess or acquire such Intellectual Property would not result, individually or in the aggregate, in a Material Adverse Change. Except as disclosed in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus under the caption "Business—Intellectual Property," or as would not be reasonably likely to result, individually or in the aggregate, in a Material Adverse Change (A) there is no infringement, misappropriation or violation by third parties of any such Intellectual Property, except as such infringement, misappropriation or violation would not result in a Material Adverse Change; (B) there is no pending or, to the knowledge of the Company and its subsidiaries, threatened action, suit, proceeding or claim by others challenging the rights of the Company and its subsidiaries in or to any such Intellectual Property, and the Company is unaware of any facts which would form a reasonable basis for any such claim, that would, individually or in the aggregate, together with any other claims in this section (xv) result in a Material Adverse Change; (C) the Intellectual Property owned by the Company and its subsidiaries and, to the knowledge of the Company, the Intellectual Property licensed to the Company and its subsidiaries has not been adjudged by a court of competent jurisdiction invalid or unenforceable, in whole or in part, and there is no pending or, to the Company's knowledge, threatened action, suit, proceeding or claim by others challenging the validity or scope of any such Intellectual Property, and the Company is unaware of any facts which would form a reasonable basis for any such claim that would,

individually or in the aggregate, together with any other claims in this section (xv) result in a Material Adverse Change; (D) there is no pending or, to the Company's knowledge, threatened action, suit, proceeding or claim by others that the Company or its subsidiaries infringe, misappropriate or otherwise violate any Intellectual Property or other proprietary rights of others, the Company and its subsidiaries have not received any written notice of such claim and the Company is unaware of any other facts which would form a reasonable basis for any such claim that would, individually or in the aggregate, together with any other claims in this section (xv) result in a Material Adverse Change; and (E) to the Company's knowledge (as defined below), no employee of the Company or a subsidiary of the Company is in or has ever been in violation in any material respect of any term of any employment contract, patent disclosure agreement, invention assignment agreement, non-competition agreement, non-solicitation agreement, nondisclosure agreement or any restrictive covenant to or with a former employer where the basis of such violation relates to such employee's employment with the Company or a subsidiary of the Company, or actions undertaken by the employee while employed with the Company or a subsidiary of the Company and could result, individually or in the aggregate, in a Material Adverse Change. To the Company's knowledge, all material technical information developed by and belonging to the Company and its subsidiaries which has not been patented has been kept confidential. The Company is not a party to or bound by any options, licenses or agreements with respect to the Intellectual Property that are required to be set forth in the Registration Statement, in the Time of Sale Disclosure Package and in the Prospectus and are not described therein. The term "Intellectual Property" as used herein means all patents, patent applications, trade and service marks, trade and service ▇▇▇▇ registrations, trade names, copyrights, licenses, inventions, trade secrets, technology, know-how and other intellectual property. The term "to the Company's knowledge" and any similar terms used in this subsection (xv) herein refer to the knowledge of the members of the Company's Board of Directors, all of the Company's officers, and the following employees: Sr. Director Chemistry, Sr. Director Biology and Research Investigator—Pharmacology.

(xvi) Neither the Company nor its subsidiaries is (A) in violation of its respective charter, by-laws or other organizational documents; (B) in breach of or otherwise in default, and no event has occurred which, with notice or lapse of time or both, would constitute such a default in the performance or observance of any term, covenant, obligation, agreement or condition contained in any bond, debenture, note, indenture, loan agreement, mortgage, deed of trust or any other contract, lease or other instrument to which it is subject or by which it may be bound, or to which any of the material property or assets of the Company or any of its subsidiaries is subject or (C) in violation of any law or statute or any order, rule, regulation, judgment or decree of any court or arbitrator or Governmental Authority, which in the case of subsections (B) and (C), above, would be reasonably likely to have a Material Adverse Effect.

(xvii) The Company and its subsidiaries have accurately prepared and timely filed all federal, state, local and foreign income, franchise and other tax returns required to be filed and are not in default in the payment of any taxes which were payable pursuant to said returns or any assessments with respect thereto, other than any which the Company is contesting in good faith, including without limitation, all sales and use taxes and all taxes which the Company or any of its subsidiaries is obligated to withhold from amounts owing to employees, creditors and third parties, with respect to the periods covered by such tax returns (whether or not such amounts are shown as due on any tax return). There is no pending dispute with any taxing authority relating to any of such returns and the Company has no knowledge of any proposed liability for any tax to be imposed upon the properties or assets of the Company or any of its subsidiaries for which there is not an adequate reserve reflected in the Company's financial statements included in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus, and since December 31, 2005, the Company has not incurred any liability for taxes other than in the ordinary course of their business. There is no tax lien, whether imposed by any federal, state, foreign or other taxing authority, outstanding against the assets, properties or business of the Company or any of its subsidiaries.

(xviii) The Company has not distributed and will not distribute any prospectus or other offering material in connection with the offering and sale of the Securities other than any Preliminary Prospectus, the Time of Sale Disclosure Package or the Prospectus or other materials permitted by the Act to be distributed by the Company; provided, however, that, except as set forth on Schedule II, the Company has not made and will not make any offer relating to the Securities that would constitute a "free writing prospectus" as defined in Rule 405, except in accordance with the provisions of Section 4(a)(xx) of this Agreement.

(xix) The Securities have been approved for listing on the Nasdaq Global Market upon official notice of issuance and, on the date the Registration Statement became or becomes effective, the Company's Registration Statement on Form 8-A or other applicable form under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), became or will become effective. There are no affiliations with the NASD among the Company's officers or directors.

(xx) The Company maintains a system of internal accounting controls sufficient to provide reasonable assurances that (A) transactions are executed in accordance with management's general or specific authorization; (B) transactions are recorded as necessary to permit preparation of financial statements in conformity with generally accepted accounting principles in the United States and to maintain accountability for assets; (C) access to assets is permitted only in accordance with management's general or specific authorization; and (D) the recorded accountability for assets is compared with existing assets at reasonable intervals and appropriate action is taken with respect to any differences. The Company maintains a system of internal control over financial reporting (as such term is defined in Rule 13a-15(f) under the Exchange Act) that complies with the requirements of the Exchange Act and has been designed by the Company's principal executive officer and principal financial officer, or under their supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles in the United States. Except as disclosed in the Registration Statement, in the Time of Sale Disclosure Package and in the Prospectus, the Company's internal control over financial reporting is effective and the Company is not aware of any material weaknesses in its internal control over financial reporting, and since the end of the latest audited fiscal year, there has been no change in the Company's internal control over financial reporting (whether or not remediated) that has materially affected, or is reasonably likely to materially affect, the Company's internal control over financial reporting.

(xxi) The Company's board of directors has validly appointed an audit committee whose composition satisfies the applicable requirements of Rule 4350(d)(2) of the Rules of the NASD (the "NASD Rules") and the Company's board of directors and/or the audit committee has adopted a charter that satisfies the requirements of Rule 4350(d)(1) of the NASD Rules. Neither the Company's board of directors nor the audit committee has been informed, nor is any director of the Company aware, of (A) any significant deficiencies in the design or operation of the Company's internal controls which could adversely affect the Company's ability to record, process, summarize and report financial data or any material weakness in the Company's internal controls; or (B) any fraud, whether or not material, that involves management or other employees of the Company who have a significant role in the Company's internal controls.

(xxii) No relationship, direct or indirect, exists between or among the Company and its subsidiaries, on the one hand, and the directors, officers, stockholders, customers or suppliers of the Company and its subsidiaries, on the other hand, which is required to be described in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus which is not so described. Neither the Company nor its subsidiaries has, directly or indirectly, extended

or maintained credit, or arranged for the extension of credit, or renewed an extension of credit, in the form of a personal loan to or for any of their directors or executive officers in violation of applicable laws, including Section 402 of the ▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act.

(xxiii) Except as described in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus, the Company and its subsidiaries: (A) are and at all times have complied in all material respects with all statutes, rules, regulations, or guidances applicable to the ownership, testing, development, manufacture, packaging, processing, use, distribution, marketing, labeling, promotion, sale, offer for sale, storage, import, export or disposal of any product manufactured or distributed by the Company and its subsidiaries ("Applicable Laws"); (B) have not received any FDA Form 483, notice of adverse finding, warning letter, untitled letter or other correspondence or notice from the U.S. Food and Drug Administration or any other Governmental Authority alleging or asserting noncompliance with any Applicable Laws or any licenses, certificates, approvals, clearances, authorizations, permits and supplements or amendments thereto required by any such Applicable Laws ("Authorizations"); (C) possess all Authorizations and such Authorizations are valid and in full force and effect and are not in violation of any term of any such Authorizations; (D) have not received notice of any claim, action, suit, proceeding, hearing, enforcement, investigation, arbitration or other action from any Governmental Authority or third party alleging that any product operation or activity is in violation of any Applicable Laws or Authorizations and have no knowledge that any such Governmental Authority or third party is considering any such claim, litigation, arbitration, action, suit, investigation or proceeding; (E) have not received notice that any Governmental Authority has taken, is taking or intends to take action to limit, suspend, modify or revoke any Authorizations and have no knowledge that any such Governmental Authority is considering such action; (F) have filed, obtained, maintained or submitted all reports, documents, forms, notices, applications, records, claims, submissions and supplements or amendments as required by any Applicable Laws or Authorizations and represent that all such reports, documents, forms, notices, applications, records, claims, submissions and supplements or amendments were complete and correct in all material respects on the date filed (or were corrected or supplemented by a subsequent submission); and (G) have not, either voluntarily or involuntarily, initiated, conducted, or issued or caused to be initiated, conducted or issued, any recall, market withdrawal or replacement, safety alert, post-sale warning, "dear doctor" letter, or other notice or action relating to the alleged lack of safety or efficacy of any product or any alleged product defect or violation and, to the Company's knowledge, no third party has initiated, conducted or intends to initiate any such notice or action.

(xxiv) The studies, tests and preclinical and clinical trials conducted by or on behalf of the Company and its subsidiaries were and, if still pending, are being conducted in material compliance with experimental protocols, procedures and controls pursuant to accepted professional scientific standards and all Applicable Laws and Authorizations, including, without limitation, the Federal Food, Drug and Cosmetic Act and the rules and regulations promulgated thereunder (collectively, "FFDCA"); the descriptions of the results of such studies, tests and trials contained in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus are accurate and complete in all material respects and fairly present the data derived from such studies, tests and trials; except to the extent disclosed in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus, the Company is not aware of any studies, tests or trials, the results of which the Company believes reasonably call into question the study, test, or trial results described or referred to in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus when viewed in the context in which such results are described and the clinical state of development; and the Company and its subsidiaries have not received any notices or correspondence from any Governmental Authority requiring the termination, suspension or material modification of any

studies, tests or preclinical or clinical trials conducted by or on behalf of the Company or its subsidiaries.

(xxv) The Company and its subsidiaries (A) have complied in all material respects with any and all applicable federal, state, local and foreign laws, rules, regulations, decisions and orders relating to the protection of human health and safety, the environment or hazardous or toxic substances or wastes, pollutants or contaminants (collectively, "Environmental Laws"); (B) have received and complied in all material respects with all permits, licenses or other approvals required of them under applicable Environmental Laws to conduct their business; and (C) have not received notice of any actual or potential liability for the investigation or remediation of any disposal or release of hazardous or toxic substances or wastes, pollutants or contaminants, except in any such case for any such failure to comply, or failure to receive required permits, licenses or approvals, or liability as would not, individually or in the aggregate, result in a Material Adverse Change. The Company and its subsidiaries have not agreed to assume, undertake or provide indemnification for any liability of any other person under any Environmental Law, including any obligation for cleanup or remedial action, except as could not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect. No property of the Company or its subsidiaries is subject to any lien under any Environmental Law. The Company and its subsidiaries are not subject to any order, decree, agreement or other individualized legal requirement related to any Environmental Law.

(xxvi) The Company and its subsidiaries (A) are in compliance, in all material respects, with any and all applicable foreign, federal, state and local laws, rules, regulations, treaties, statutes and codes promulgated by any and all governmental authorities (including pursuant to the Occupational Health and Safety Act) relating to the protection of human health and safety in the workplace ("Occupational Laws"); (B) have received all material permits, licenses or other approvals required of them under applicable Occupational Laws to conduct their business as currently conducted; and (C) are in compliance, in all material respects, with all terms and conditions of such permits, licenses or approvals. No action, proceeding, revocation proceeding, writ, injunction or claim is pending or, to the Company's knowledge, threatened against the Company or its subsidiaries relating to Occupational Laws.

(xxvii) Each employee benefit plan, within the meaning of Section 3(3) of the Employee Retirement Income Security Act of 1974, as amended ("ERISA"), that is maintained, administered or contributed to by the Company or any of its affiliates for employees or former employees of the Company and its subsidiaries has been maintained in compliance in all material respects with its terms and the requirements of any applicable statutes, orders, rules and regulations, including ERISA and the Internal Revenue Code of 1986, as amended (the "Code"). The Company and its subsidiaries have not incurred and do not expect to incur liability under Title IV of ERISA with respect to the termination of, or withdrawal from any "pension plan;" and each plan for which the Company or its subsidiaries would have any liability that is intended to be qualified under Section 401(a) of the Code is so qualified and nothing has occurred, whether by action or by failure to act, which could cause the loss of such qualification. No prohibited transaction, within the meaning of Section 406 of ERISA or Section 4975 of the Code, has occurred with respect to any such plan excluding transactions effected pursuant to a statutory or administrative exemption; and for each such plan that is subject to the funding rules of Section 412 of the Code or Section 302 of ERISA, no "accumulated funding deficiency" as defined in Section 412 of the Code has been incurred, whether or not waived, and the fair market value of the assets of each such plan (excluding for these purposes accrued but unpaid contributions) exceeds the present value of all benefits accrued under such plan determined using reasonable actuarial assumptions.

(xxviii) No labor disturbance by the employees of the Company or its subsidiaries exists or, to the best of the Company's knowledge, is imminent and the Company is not aware of any existing or imminent labor disturbances by the employees of any of its principal suppliers, manufacturers, customers or contractors, which, in either case (individually or in the aggregate), could reasonably be expected to have a Material Adverse Effect.

(xxix) Except as disclosed in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus, neither the Company nor its subsidiaries has granted rights to develop, manufacture, produce, assemble, distribute, license, market or sell its product candidates to any other person or is bound by any agreement that affects the exclusive right of the Company or any such subsidiary to develop, manufacture, produce, assemble, distribute, license, market or sell its product candidates.

(xxx) The statistical, industry-related and market-related data included in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus are based on or derived from sources which the Company reasonably believes are reliable and accurate, and such data agree with the sources from which they are derived.

(xxxi) Other than as contemplated by this Agreement, the Company has not incurred any liability for any finder's or broker's fee or agent's commission in connection with the execution and delivery of this Agreement or the consummation of the transactions contemplated hereby. Except as disclosed in the Time of Sale Disclosure Package and the Prospectus, there are no contracts, agreements or understandings between the Company and any person that would give rise to a valid claim against the Company or any Underwriter for a brokerage commission, finder's fee or other like payment in connection with the transactions contemplated by this Agreement or, to the Company's knowledge, any arrangements, agreements, understandings, payments or issuance with respect to the Company or any of its officers, directors, shareholders, partners, employees, subsidiaries or affiliates that may affect the Underwriters' compensation as determined by the NASD.

(xxxii) Neither the Company nor any of its affiliates is presently doing business with the government of Cuba or with any person or affiliate located in Cuba.

(xxxiii) The Company carries, or is covered by, insurance issued by insurers of nationally recognized financial responsibility in such amounts and covering such risks as is reasonably adequate for the conduct of its business and the value of its properties and as is customary for companies of similar size and development stage engaged in similar businesses in similar industries; and the Company has not received notice from any insurer or agent of such insurer that either (A) capital improvements or other expenditures are required or necessary to be made in order to continue such insurance or (B) its existing insurance coverage as and when such coverage expires will not be renewed. In the event of a non-renewal, the Company would be able to obtain similar coverage at reasonable cost that would not have a Material Adverse Effect from similar insurers as may be necessary to continue its business. The Company's existing insurance is outstanding and duly in full force and effect on the date hereof. There are no material claims by the Company under any such policy or instrument as to which any insurance company is currently defending under a reservation of rights clause or with respect to which the insurer has notified the Company in writing of a denial of coverage.

(xxxiv) None of the Company, its subsidiaries or, to the knowledge of the Company, any director, officer, agent, employee or other person associated with or acting on behalf of the Company or its subsidiaries has (A) used any corporate funds for any unlawful contribution, gift, entertainment or other unlawful expense relating to political activity; (B) made any direct or indirect unlawful payment to any foreign or domestic government official or employee from corporate funds; (C) violated or is in violation of any provision of the Foreign Corrupt

Practices Act of 1977; or (D) made any bribe, rebate, payoff, influence payment, kickback or other unlawful payment. The operations of the Company and its subsidiaries are and have been conducted at all times in compliance in all material respects with applicable financial record-keeping and reporting requirements of the Currency and Foreign Transactions Reporting Act of 1970, as amended, the money laundering statutes of all applicable jurisdictions, the rules and regulations thereunder and any related or similar rules, regulations or guidelines issued, administered or enforced by any governmental agency (collectively, the "Money Laundering Laws") and no action, suit or proceeding by or before any court or governmental agency, authority or body or any arbitrator involving the Company or its subsidiaries with respect to the Money Laundering Laws is pending or, to the best knowledge of the Company, threatened. None of the Company, its subsidiaries or, to the knowledge of the Company, any director, officer, agent, employee or affiliate of the Company or its subsidiaries is currently subject to any U.S. sanctions administered by the Office of Foreign Assets Control of the U.S. Treasury Department ("OFAC"); and the Company will not directly or indirectly use the proceeds of the offering of the Securities, or lend, contribute or otherwise make available such proceeds to any subsidiary, joint venture partner or other person or entity, for the purpose of financing the activities of any person currently subject to any U.S. sanctions administered by OFAC.

(xxxv) Except with notice to the Representatives and compliance with Applicable Laws, none of the Directed Stock (as defined below) distributed in connection with the Directed Stock Program (as defined below) will be offered or sold outside of the United States. The Company has not offered, or caused the Underwriters to offer, Directed Stock to any person with the intention of unlawfully influencing (A) a customer or supplier of the Company to alter the customer's or supplier's level or type of business with the Company or (B) a trade journalist or publication to write or publish favorable information about the Company or its products.

(xxxvi) The Company is not and, after giving effect to the offering and sale of the Securities, will not be required to register as an "investment company," as such term is defined in the Investment Company Act of 1940, as amended, and will not be an entity "controlled" by an "investment company" within the meaning of such Act.

(xxxvii) The Company and its directors and officers, in their capacities as such, are in compliance with all applicable provisions of the ▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act and the rules and regulations of the Commission thereunder, including, without limitation, Section 402 related to loans.

(xxxviii) The Company has established and maintains disclosure controls and procedures (as defined in Rules 13a-14 and 15d-14 under the Exchange Act) that comply with the requirements of the Exchange Act; such controls and procedures are effective in ensuring that material information relating to the Company is made known to the principal executive officer and the principal financial officer. The Company has utilized such controls and procedures in preparing and evaluating the disclosures in the Registration Statement, in the Time of Sale Disclosure Package and in the Prospectus.

(b) Each Selling Stockholder represents and warrants to, and agrees with, the several Underwriters as follows:

(i) Such Selling Stockholder is the record and beneficial owner of, and has, and on the First Closing Date and/or the Second Closing Date, as the case may be, will have, valid and marketable title to the Option Shares to be sold by such Selling Stockholder, free and clear of all security interests, claims, liens, restrictions on transferability, legends, proxies, equities or other encumbrances; and upon delivery of and payment for such Option Shares hereunder,

the several Underwriters will acquire valid and marketable title thereto, free and clear of any security interests, claims, liens, restrictions on transferability, legends, proxies, equities or other encumbrances. Such Selling Stockholder is selling the Option Shares to be sold by such Selling Stockholder for such Selling Stockholder's own account and is not selling such Option Shares, directly or indirectly, for the benefit of the Company, and no part of the proceeds of such sale received by such Selling Stockholder will inure, either directly or indirectly, to the benefit of the Company other than as described in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus.

(ii) Each Selling Stockholder has duly authorized, executed and delivered an Irrevocable Power of Attorney and Custody Agreement (the "IPA and Custody Agreement"), authorizing and directing [ ] and [ ], or either of them, as attorneys-in-fact (the "Attorneys-in-Fact"), to effect the sale and delivery of the Option Shares being sold by such Selling Stockholder, to enter into this Agreement and to take all such other action as may be necessary hereunder; such IPA and Custody Agreement is a valid and binding obligation of such Selling Stockholder to [ ], as Custodian (the "Custodian"), except as rights to indemnity hereunder may be limited by federal or state securities laws and except as such enforceability may be limited by bankruptcy, insolvency, reorganization or similar laws affecting the rights of creditors generally and subject to general principles of equity; pursuant to the IPA and Custody Agreement, the Selling Stockholder has placed in custody with the Custodian, for delivery under this Agreement, the certificates representing the Option Shares to be sold by such Selling Stockholder; such certificates represent validly issued, outstanding, fully paid and nonassessable shares of Common Stock; and such certificates were duly and properly endorsed in blank for transfer, or were accompanied by all documents duly and properly executed that are necessary to validate the transfer of title thereto, to the Underwriters, free of any legend, restriction on transferability, proxy, lien or claim, whatsoever.

(iii) This Agreement and the IPA and Custody Agreement have each been duly authorized, executed and delivered by or on behalf of such Selling Stockholder and each constitutes a valid, legal and binding obligation of such Selling Stockholder, enforceable in accordance with its terms, except as rights to indemnity hereunder or thereunder may be limited by federal or state securities laws and except as such enforceability may be limited by bankruptcy, insolvency, reorganization or similar laws affecting the rights of creditors generally and subject to general principles of equity. The execution, delivery and performance of this Agreement and the IPA and Custody Agreement and the consummation of the transactions herein and therein contemplated will not (A) conflict with or result in a breach or violation of any of the terms or provisions of, or constitute a default under, or result in the creation or imposition of any lien, charge or encumbrance upon any property or assets of such Selling Stockholder pursuant to, any indenture, mortgage, deed of trust, loan agreement or other agreement or instrument to which such Selling Stockholder is a party or by which such Selling Stockholder is bound or to which any of the property or assets of such Selling Stockholder is subject, unless such conflict, breach, violation or default would not adversely affect such Selling Stockholder's ability to perform any of its obligations under the Agreement and the IPA and Custody Agreement or any of the transactions contemplated hereby or thereby, (B) result in any violation of the provision of the charter, by-laws or other governing instruments of such Selling Stockholder, if applicable or (C) result in the violation of any law or statute or any judgment, order, rule or regulation of any court or arbitrator or governmental or regulatory authority. No consent, approval, authorization or order of, or filing with, any court or governmental agency or body is required for the execution, delivery and performance of this Agreement and the IPA and Custody Agreement or for the consummation of the transactions contemplated hereby and thereby, including the sale of the Option Shares

being sold by such Selling Stockholder, except such as may be required under the Act, foreign securities laws or state securities laws or blue sky laws or under the rules and regulations of the NASD; and such Selling Stockholder has full power and authority to enter into this Agreement and the IPA and Custody Agreement and to consummate the transactions contemplated hereby and thereby including the sale of the Option Shares as contemplated by this Agreement.

(iv) Such Selling Stockholder has not distributed and will not distribute any prospectus or other offering material in connection with the offering and sale of the Option Shares other than any Preliminary Prospectus, the Time of Sale Disclosure Package or the Prospectus or other materials permitted by the Act to be distributed by such Selling Stockholder; provided, however, that no Selling Stockholder has made nor will make any offer relating to the Option Shares that would constitute a "free writing prospectus" as defined in Rule 405 except a Permitted Free Writing Prospectus authorized by the Company and the Underwriters for distribution in accordance with the provisions of Section 4(a)(xix) hereof.

(v) If such Selling Stockholder is not a natural person, such Selling Stockholder has been duly organized and is validly existing and (if applicable) in good standing under the laws of the jurisdiction of its organization.

(vi) The Option Shares to be sold by such Selling Stockholder under this Agreement are not subject to any option, warrant, put, call, right of first refusal or other right to purchase or otherwise acquire any such Securities other than pursuant to this Agreement.

(vii) Such Selling Stockholder does not have any preemptive rights, rights of first refusal or other similar rights to purchase or otherwise acquire any of the Option Shares that are to be sold by any of the other Selling Stockholders, if any, pursuant to this Agreement.

(viii) Such Selling Stockholder has reviewed the Registration Statement, the Time of Sale Disclosure Package and the Prospectus and neither the Registration Statement, the Time of Sale Disclosure Package nor the Prospectus contains any untrue statement of a material fact or omits to state any material fact required to be stated therein or necessary to make the statements therein not misleading regarding such Selling Stockholder, and, to the knowledge of such Selling Stockholder, the other Selling Stockholders, if any, the Company or otherwise; provided that, any claim for damages for a breach of the Selling Stockholder's representation and warranty concerning statements in the Registration Statement, the Time of Sale Disclosure Package and the Prospectus with respect to the other Selling Stockholders, if any, the Company or otherwise shall be limited to the gross proceeds from the sale of the Selling Stockholder's Securities. All information relating to each Selling Stockholder furnished or confirmed in writing by or on behalf of such Selling Stockholder expressly for use in the Registration Statement (or any amendment thereto), any Preliminary Prospectus or the Prospectus (or any amendment or supplement thereto) or in the Time of Sale Disclosure Package is and will be true, complete and correct; and such Selling Stockholder is not prompted to sell the Securities to be sold by such Selling Stockholder under this Agreement by any information concerning the Company which is not set forth in the Registration Statement, the Time of Sale Disclosure Package or the Prospectus.

(ix) To the knowledge of such Selling Stockholder, the representations and warranties of the Company contained in paragraph (a) of this Section 2 are true and correct.

(c) Any certificate contemplated hereby or delivered in connection with the sale of Securities consummated by this Agreement and signed by any officer of the Company and delivered to you or to counsel for the Underwriters shall be deemed a representation and warranty by the Company to each Underwriter as to the matters covered thereby; any certificate signed by or on behalf of

any Selling Stockholder as such and delivered to you or to counsel for the Underwriters in connection with the transactions contemplated by this Agreement shall be deemed a representation and warranty by such Selling Stockholder to each Underwriter as to the matters covered thereby.

3. Purchase, Sale and Delivery of Securities.

(a) On the basis of the representations, warranties and agreements herein contained, but subject to the terms and conditions herein set forth, the Company agrees to issue and sell the Firm Shares to the several Underwriters, and each Underwriter agrees, severally and not jointly, to purchase from the Company the number of Firm Shares set forth opposite the name of such Underwriter in Schedule I hereto. The purchase price for each Firm Share shall be $[ ] per share. The obligation of each Underwriter to the Company shall be to purchase from the Company that number of Firm Shares (to be adjusted by the Representatives to avoid fractional shares) which represents the same proportion of the number of Firm Shares to be sold by the Company pursuant to this Agreement as the number of Firm Shares set forth opposite the name of such Underwriter in Schedule I hereto represents to the total number of Firm Shares to be purchased by all Underwriters pursuant to this Agreement.

(b) It is understood that [ ] shares of the Firm Shares ("Directed Stock") will initially be reserved by the Underwriters for offer and sale to employees and persons having relationships with the Company or its employees ("Directed Stock Participants") upon the terms and conditions set forth in the Prospectus and in accordance with the rules and regulations of the NASD ("Directed Stock Program"). Under no circumstances will the Representatives or any Underwriter be liable to the Company or to any Directed Stock Participant for any action taken or omitted to be taken in good faith in connection with such Directed Stock Program. To the extent that any shares of Directed Stock are not affirmatively reconfirmed for purchase by any Directed Stock Participant on or immediately after the date of this Agreement, such Directed Stock may be offered to the public as part of the public offering contemplated hereby. The Company agrees to pay all fees and disbursements incurred by the Underwriters in connection with the Directed Stock Program, including counsel fees and any stamp duties or other taxes incurred by the Underwriters in connection with the Directed Stock Program.

The Firm Shares will be delivered by the Company to you for the accounts of the several Underwriters against payment of the purchase price therefor by wire transfer of same day funds payable to the order of the Company at the offices of ▇▇▇▇▇▇ & ▇▇▇▇▇▇▇ LLP, ▇▇▇▇▇ ▇▇▇▇ ▇▇▇▇▇ ▇▇▇▇▇, ▇▇▇▇▇ ▇▇▇, ▇▇▇ ▇▇▇▇▇, ▇▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇, or such other location as may be mutually acceptable, at 10:00 a.m. Eastern Standard Time on the third (or if the Securities are priced, as contemplated by Rule 15c6-1(c) under the Exchange Act, after 1:30 p.m. Pacific time, the fourth) full business day following the date hereof, or at such other time and date as you and the Company determine pursuant to Rule 15c6-1(a) under the Exchange Act, such time and date of delivery being herein referred to as the "First Closing Date." If the Representatives so elect, delivery of the Firm Shares may be made by credit through full fast transfer to the accounts at The Depository Trust Company designated by the Representatives. Certificates representing the Firm Shares, in definitive form and in such denominations and registered in such names as you may request upon at least two business days' prior notice to the Company, will be made available for checking and packaging not later than 8:30 a.m., Pacific Time, on the business day next preceding the First Closing Date at the offices of ▇▇▇▇▇▇ & ▇▇▇▇▇▇▇ LLP, ▇▇▇▇▇ ▇▇▇▇ ▇▇▇▇▇ ▇▇▇▇▇, ▇▇▇▇▇ ▇▇▇, ▇▇▇ ▇▇▇▇▇, ▇▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇, or such other location as may be mutually acceptable.

(c) On the basis of the representations, warranties and agreements herein contained, but subject to the terms and conditions herein set forth, each Selling Stockholder, with respect to the number of Option Shares set forth opposite the name of such Selling Stockholder in Schedule II hereto, hereby grants to the several Underwriters an option to purchase all or any portion of the Option Shares at the same purchase price as the Firm Shares, for use solely in covering any over-allotments made by the Underwriters in the sale and distribution of the Firm Shares. The option granted hereunder may be exercised in whole or in part at any time (but not more than once) within 30 days after the effective date of this Agreement upon notice (confirmed in writing) by the Representatives to the Attorneys-in-Fact setting forth the aggregate number of Option Shares as to which the several Underwriters are exercising the option, the names and denominations in which the certificates for the Option Shares are to be registered and the date and time, as determined by you, when the Option Shares are to be delivered, such time and date being herein referred to as the "Second Closing" and "Second Closing Date," respectively; provided, however, that the Second Closing Date shall not be earlier than the First Closing Date nor earlier than the second business day after the date on which the option shall have been exercised. If the option is exercised, the number of Option Shares to be purchased by each Underwriter from each Selling Stockholder shall be that number of Option Shares which represents the same proportion that the number of Option Shares granted by such Selling Stockholder bears to the total number of Option Shares granted by all Selling Stockholders, as adjusted by the Representatives in such manner as the Representatives deem advisable to avoid fractional shares. The number of Option Shares to be purchased by each Underwriter shall be the same percentage of the total number of Option Shares to be purchased by the several Underwriters as the number of Firm Shares to be purchased by such Underwriter is of the total number of Firm Shares to be purchased by the several Underwriters, as adjusted by the Representatives in such manner as the Representatives deem advisable to avoid fractional shares. No Option Shares shall be sold and delivered unless the Firm Shares previously have been, or simultaneously are, sold and delivered.

The Option Shares will be delivered by the Custodian to you for the accounts of the several Underwriters against payment of the purchase price therefor by wire transfer of same day funds payable to the order of the Company, as appropriate, at the offices of ▇▇▇▇▇▇ & ▇▇▇▇▇▇▇ LLP, ▇▇▇▇▇ ▇▇▇▇ ▇▇▇▇▇ ▇▇▇▇▇, ▇▇▇▇▇ ▇▇▇, ▇▇▇ ▇▇▇▇▇, ▇▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇, or such other location as may be mutually acceptable at 10:00 a.m., Eastern Time, on the Second Closing Date. If the Representatives so elect, delivery of the Option Shares may be made by credit through full fast transfer to the accounts at The Depository Trust Company designated by the Representatives. Certificates representing the Option Shares in definitive form and in such denominations and registered in such names as you have set forth in your notice of option exercise, will be made available for checking and packaging not later than 8:30 a.m., Pacific Time, on the business day next preceding the Second Closing Date at the offices of ▇▇▇▇▇▇ & ▇▇▇▇▇▇▇ LLP, ▇▇▇▇▇ ▇▇▇▇ ▇▇▇▇▇ ▇▇▇▇▇, ▇▇▇▇▇ ▇▇▇, ▇▇▇ ▇▇▇▇▇, ▇▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇, or such other location as may be mutually acceptable.

(d) It is understood that you, individually and not as Representatives of the several Underwriters, may (but shall not be obligated to) make payment to the Company (in the case of Firm Shares) or to the Selling Stockholders (in the case of Option Shares), on behalf of any Underwriter for the Securities to be purchased by such Underwriter. Any such payment by you shall not relieve any such Underwriter of any of its obligations hereunder. Nothing herein contained shall constitute any of the Underwriters an unincorporated association or partner with the Company or any Selling Stockholder.

4. Covenants.

(a) The Company covenants and agrees with the several Underwriters as follows:

(i) If the Registration Statement has not already been declared effective by the Commission, the Company will use its best efforts to cause the Registration Statement and any post-effective amendments thereto to become effective as promptly as possible; the Company will notify you promptly of (A) the time when the Registration Statement or any post-effective amendment to the Registration Statement has become effective or any supplement to the Prospectus has been filed, (B) any request by the Commission for any amendment or supplement to the Registration Statement or Prospectus or additional information, (C) the Company's intention to file, or prepare any supplement or amendment to, the Registration Statement, any Preliminary Prospectus, the Prospectus or any Issuer Free Writing Prospectus, (D) the mailing or the delivery to the Commission for filing of any amendment or supplement to the Registration Statement or the Prospectus, (E) the receipt of comments from the Commission and (F) the receipt by the Company of any notification with respect to the suspension of the qualification of the Securities for sale in any jurisdiction or the initiation or threatening of any proceeding for that purpose; if the Company has elected to rely on Rule 430A, the Company will prepare and file a Prospectus containing the information omitted therefrom pursuant to Rule 430A with the Commission within the time period required by, and otherwise in accordance with the provisions of, Rules 424(b) and 430A; if the Company has elected to rely upon Rule 462(b) to increase the size of the offering registered under the Act, the Company will prepare and file a registration statement with respect to such increase with the Commission within the time period required by, and otherwise in accordance with the provisions of, Rule 462(b); the Company will prepare and file with the Commission, promptly upon your request, any amendments or supplements to the Registration Statement or Prospectus that, in your opinion, may be necessary or advisable in connection with the distribution of the Securities by the Underwriters; and the Company will furnish the Representatives and counsel for the Underwriters a copy of any proposed amendment or supplement to the Registration Statement or Prospectus and will not file any amendment or supplement to the Registration Statement or Prospectus to which you shall reasonably object by notice to the Company after having been furnished a copy at a reasonable time prior to the filing.

(ii) The Company will advise you, promptly after it shall receive notice or obtain knowledge thereof, of the issuance by the Commission of any stop order suspending the effectiveness of the Registration Statement, or any post-effective amendment thereto or preventing or suspending the use of any Preliminary Prospectus, the Time of Sale Disclosure Package, the Prospectus or any Issuer Free Writing Prospectus, of the suspension of the qualification of the Securities for offering or sale in any jurisdiction, or of the initiation or threatening of any proceeding for any such purpose; and the Company will promptly use its best efforts to prevent the issuance of any stop order or to obtain its withdrawal if such a stop order should be issued. Additionally, the Company agrees that it shall comply with the provisions of Rules 424(b) and 430A, as applicable, and will use its reasonable efforts to confirm that any filings made by the Company under Rule 424(b), Rule 433 or Rule 462 were received in a timely manner by the Commission.

(iii) (A) Within the time during which a prospectus (or in lieu thereof the notice referred to in Rule 173(a) of the Rules and Regulations) relating to the Securities is required to be delivered under the Act, the Company will comply as far as it is able with all requirements imposed upon it by the Act, as now and hereafter amended, and by the Rules and Regulations, as from time to time in force, so far as necessary to permit the continuance of sales of or dealings in the Securities as contemplated by the provisions hereof, the Time of

Sale Disclosure Package and the Prospectus. If during such period any event shall occur or condition shall exist as a result of which the Prospectus (or, if the Prospectus is not yet available to prospective purchasers, the Time of Sale Disclosure Package) would include an untrue statement of a material fact or omit to state a material fact necessary to make the statements therein, in the light of the circumstances then existing, not misleading, or if during such period it is necessary to amend the Registration Statement or supplement the Prospectus (or, if the Prospectus is not yet available to prospective purchasers, the Time of Sale Disclosure Package) to comply with the Act, the Company will promptly notify you and will amend the Registration Statement or supplement the Prospectus (or, if the Prospectus is not yet available to prospective purchasers, the Time of Sale Disclosure Package) (at the expense of the Company) so as to correct such statement or omission or effect such compliance.

(B) If at any time following issuance of an Issuer Free Writing Prospectus, there occurred or occurs an event or development as a result of which such Issuer Free Writing Prospectus conflicted or would conflict with the information contained in the Registration Statement, any Statutory Prospectus or the Prospectus relating to the Securities or included or would include an untrue statement of a material fact or omitted or would omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances prevailing at that subsequent time, not misleading, the Company has promptly notified or promptly will notify the Representatives and has promptly amended or will promptly amend or supplement, at its own expense, such Issuer Free Writing Prospectus to eliminate such conflict or correct such untrue statement or omission.

(iv) The Company shall take or cause to be taken all necessary action to qualify the Securities for sale under the securities laws of such jurisdictions as you reasonably designate or as is necessary to effect the distribution of the Directed Stock and to continue such qualifications in effect so long as required for the distribution of the Securities, except that the Company shall not be required in connection therewith to qualify as a foreign corporation or to execute a general consent to service of process in any state.

(v) The Company will furnish or make available to the Underwriters and counsel for the Underwriters copies of the Registration Statement (up to a total of four of which will be signed and will include all consents and exhibits filed therewith, as you may request), each Preliminary Prospectus, the Time of Sale Disclosure Package, the Prospectus, any Issuer Free Writing Prospectus and all amendments and supplements to such documents, in each case as soon as available and in such quantities as you may from time to time reasonably request, and will maintain in the Company's files manually signed copies of such documents for at least five years after the date of filing.

(vi) During a period of five years commencing with the date hereof, the Company will furnish or make available to the Representatives, and to each Underwriter who may so request in writing, copies of all reports or other communications (financial or other) furnish or make available to security holders or from time to time published or publicly disseminated by the Company, and will deliver to you (A) as soon as they are available, copies of any reports, financial statements and proxy or information statements furnished to or filed with the Commission, the NASD or any national securities exchange on which any class of securities of the Company is listed; and (B) such additional information concerning the business and financial condition of the Company as you may from time to time reasonably request (such financial information to be on a consolidated basis to the extent the accounts of the Company in reports furnished or made available to its security holders generally or to the Commission); provided that the requirements of this subsection (vi) shall be satisfied to the extent the

reports, communications, financial statements or other documents referenced herein are available on the Commission's Electronic Data Gathering, Analysis and Retrieval System.

(vii) The Company will make generally available to its security holders as soon as practicable, but in any event not later than 15 months after the end of the Company's current fiscal quarter, an earnings statement (which need not be audited) covering a 12-month period beginning after the effective date of the Registration Statement that shall satisfy the provisions of Section 11(a) of the Act and Rule 158 of the Rules and Regulations.

(viii) The Company, whether or not the transactions contemplated hereunder are consummated or this Agreement is prevented from becoming effective under the provisions of Section 9(a) hereof or is terminated, will pay or cause to be paid (A) all expenses (including transfer taxes allocated to the respective transferees) incurred in connection with the delivery to the Underwriters of the Securities, (B) all expenses and fees (including, without limitation, fees and expenses of the Company's accountants and counsel but, except as otherwise provided below, not including fees of the Underwriters' counsel) in connection with the preparation, printing, filing, delivery, and shipping of the Registration Statement (including the financial statements therein and all amendments, schedules, and exhibits thereto), the Securities, each Preliminary Prospectus, the Time of Sale Disclosure Package, the Prospectus, any Issuer Free Writing Prospectus and any amendment thereof or supplement thereto, and the printing, delivery, and shipping of this Agreement and other underwriting documents, including Blue Sky Memoranda (covering the states and other applicable jurisdictions), (C) all filing fees and reasonable fees and disbursements of the Underwriters' counsel incurred in connection with the qualification of the Securities for offering and sale by the Underwriters or by dealers under the securities or blue sky laws of the states and other jurisdictions which you shall designate or are necessary to distribute the Directed Stock, (D) the fees and expenses of any transfer agent or registrar, (E) the filing fees and reasonable fees and disbursements of the Underwriters' counsel incident to any required review by the NASD of the terms of the sale of the Securities, (F) listing fees, if any, (G) the costs and expenses relating to investor presentations on any "road show" undertaken in connection with the marketing of the Securities, (H) all fees and expenses of the Custodian and the Attorneys-in-Fact and the cost of delivering and distributing the IPA and Custody Agreement, the cost of preparing stock certificates representing the Securities and all other expenses incurred by the Selling Stockholders; provided that any such fees and expenses not paid by the Company will be paid by the Selling Stockholders, and (I) all other costs and expenses incident to the performance of its obligations hereunder that are not otherwise specifically provided for herein. If the sale of the Securities provided for herein is not consummated by reason of action by the Company pursuant to Section 9(a) hereof which prevents this Agreement from becoming effective, or by reason of any failure, refusal or inability on the part of the Company or the Selling Stockholders to perform any agreement on its part to be performed, or because any other condition of the Underwriters' obligations hereunder required to be fulfilled by the Company or the Selling Stockholders is not fulfilled, the Company will reimburse the several Underwriters for all out-of-pocket disbursements (including fees and disbursements of counsel) incurred by the Underwriters in connection with their investigation, preparing to market and marketing the Securities or in contemplation of performing their obligations hereunder. The Company shall not in any event be liable to any of the Underwriters for loss of anticipated profits from the transactions covered by this Agreement.

(ix) The Company will apply the net proceeds from the sale of the Securities to be sold by it hereunder for the purposes set forth in the Time of Sale Disclosure Package and in the Prospectus and will file such reports with the Commission with respect to the sale of the

Securities and the application of the proceeds therefrom as may be required in accordance with Rule 463 of the Rules and Regulations.

(x) The Company will not, without the prior written consent of the Lead Managers, from the date of execution of this Agreement and continuing to and including the date 180 days after the date of the Prospectus (the "Lock-Up Period") offer for sale, sell, contract to sell, pledge, grant any option for the sale of, enter into any transaction which is designed to, or might reasonably be expected to, result in the disposition (whether by actual disposition or effective economic disposition due to cash settlement or otherwise) by the Company or any affiliate, or otherwise issue or dispose of, directly or indirectly (or publicly disclose the intention to make any such offer, sale, pledge, grant, issuance or other disposition), any Common Stock or any securities convertible into or exchangeable for, or any options or rights to purchase or acquire, Common Stock, except (A) to the Underwriters pursuant to this Agreement, (B) pursuant to transactions relating to any director or employee stock option plan, stock ownership plan or dividend reinvestment plan of the Company in effect at the date of the Prospectus and described in the Prospectus and (C) pursuant to the conversion of securities or the exercise of warrants outstanding at the date of the Prospectus and described in the Prospectus. If (1) during the period that begins on the date that is 18 calendar days before the last day of the Lock-Up Period and ends on the last day of the Lock-Up Period, (a) the Company issues an earnings release, (b) the Company publicly announces material news or (c) a material event relating to the Company occurs; or (2) prior to the expiration of the Lock-Up Period, the Company announces that it will release earnings results during the 16-day period beginning on the last day of the Lock-Up Period, then the restrictions in this Agreement, unless otherwise waived by the Lead Managers in writing, shall continue to apply until the expiration of the date that is 18 calendar days after the date on which (a) the Company issues the earnings release, (b) the Company publicly announces material news or (c) a material event relating to the Company occurs. The Company will provide the Representatives, any co-managers and each shareholder subject to the Lock-Up Agreement (as defined below) with prior notice of any such announcement that gives rise to the extension of the Lock-Up Period.

(xi) The Company has caused to be delivered to you prior to the date of this Agreement a letter (the "Lock-Up Agreement") from each of the Company's directors, officers, stockholders and optionholders in substantially the form set forth on Exhibit A, and in the case of Par Pharmaceutical, Inc., substantially in the form set forth on Exhibit A-1. The Company will enforce the terms of each Lock-Up Agreement and issue stop-transfer instructions to the transfer agent for the Common Stock with respect to any transaction or contemplated transaction that would constitute a breach of or default under the applicable Lock-Up Agreement.

(xii) Neither the Company nor any of its affiliates (within the meaning of Rule 144 under the Act) has taken or will take, directly or indirectly, any action designed to or which might reasonably be expected to cause or result in, or which has constituted, the stabilization or manipulation of the price of any security of the Company to facilitate the sale or resale of the Securities, and has not effected any sales of Common Stock which are required to be disclosed in response to Item 701 of Regulation S-K under the Act which have not been so disclosed in the Registration Statement.

(xiii) Neither the Company nor any of its affiliates (within the meaning of Rule 144 under the Act) has, prior to the date hereof, made any offer or sale of any securities which could be "integrated" (within the meaning of the Act and the Rules and Regulations) with the offer and sale of the Securities pursuant to the Registration Statement.

(xiv) Except as contemplated herein, the Company will not incur any liability for any finder's or broker's fee or agent's commission in connection with the execution and delivery of this Agreement or the consummation of the transactions contemplated hereby.

(xv) The Company will comply with all applicable securities and other Applicable Laws, rules and regulations in each foreign jurisdiction in which Directed Stock is offered in connection with the Directed Stock Program.

(xvi) In connection with the Directed Stock Program to ensure that the Directed Stock will be restricted to the extent required by the NASD or the rules of such association from sale, transfer, assignment, pledge or hypothecation for a period of three months following the date of the effectiveness of the Registration Statement, the Company will direct the transfer agent to place stop-transfer restrictions upon such securities for such period of time. Should the Company release, or seek to release, from such restrictions any of the Directed Stock, the Company agrees to reimburse the Underwriters for any reasonable expense (including, without limitation, legal expenses) they incur with such release.

(xvii) The Company will file with the Commission such periodic and special reports as required by the Rules and Regulations.

(xviii) The Company will maintain such controls and other procedures, including without limitation, those required by Sections 302 and 906 of the ▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act and the applicable regulations thereunder, that are designed to ensure that information required to be disclosed by the Company in the reports that it files or submits under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in the Commission's rules and forms, including without limitation, controls and procedures designed to ensure that information required to be disclosed by the Company in the reports that it files or submits under the Exchange Act is accumulated and communicated to the Company's management, including its principal executive officer and its principal financial officer, or persons performing similar functions, as appropriate to allow timely decisions regarding required disclosure, to ensure that material information relating to Company is made known to them by others within those entities.

(xix) The Company will comply with all effective applicable provisions of the ▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act.

(xx) The Company represents and agrees that, unless it obtains the prior written consent of the Lead Managers, and each Underwriter severally represents and agrees that, unless it obtains the prior written consent of the Company and the Lead Managers, it has not made and will not make any offer relating to the Securities that would constitute an "issuer free writing prospectus," as defined in Rule 433, or that would otherwise constitute a "free writing prospectus," as defined in Rule 405, required to be filed with the Commission; provided that the prior written consent of the parties hereto shall be deemed to have been given in respect of the free writing prospectuses included in Schedule III. Any such free writing prospectus consented to by the Company and the Lead Managers is hereinafter referred to as a "Permitted Free Writing Prospectus." The Company represents that it has treated or agrees that it will treat each Permitted Free Writing Prospectus as an "issuer free writing prospectus," as defined in Rule 433, and has complied and will comply with the requirements of Rule 433 applicable to any Permitted Free Writing Prospectus, including timely Commission filing where required, legending and record keeping. The Company represents that it has satisfied and agrees that it will satisfy the conditions in Rule 433 to avoid a requirement to file with the Commission any electronic road show.

(xxi) The Company shall engage and maintain, at its expense, a registrar and transfer agent for the Securities.

(xxii) The Company will use its best efforts to maintain the listing of the Securities on the Nasdaq Global Market.

(b) Each Selling Stockholder covenants and agrees with the several Underwriters as follows:

(i) Except as otherwise agreed to by the Company and the Selling Stockholder pursuant to an outstanding registration rights agreement, a true and correct copy of which has been delivered to counsel to the Underwriters, such Selling Stockholder will pay all taxes, if any, on the transfer and sale, respectively, of the Option Shares being sold by such Selling Stockholder, the fees of such Selling Stockholder's counsel and such Selling Stockholder's proportionate share (based upon the number of Securities being offered by such Selling Stockholder pursuant to the Registration Statement) of all costs and expenses (except for legal and accounting expenses and fees of the registrar and transfer agent) incurred by the Company pursuant to the provisions of Section 4(a)(viii) of this Agreement; provided, however, that each Selling Stockholder severally agrees to reimburse the Company for any reimbursement made by the Company to the Underwriters pursuant to Section 4(a)(viii) hereof to the extent such reimbursement resulted from the failure or refusal on the part of such Selling Stockholder to comply under the terms or fulfill any of the conditions of this Agreement.

(ii) If this Agreement shall be terminated by the Underwriters because of any failure, refusal or inability on the part of such Selling Stockholder to perform any agreement on such Selling Stockholder's part to be performed, or because any other condition of the Underwriters' obligations hereunder required to be fulfilled by such Selling Stockholder is not fulfilled, such Selling Stockholder agrees to reimburse the several Underwriters for all out-of-pocket disbursements (including fees and disbursements of counsel for the Underwriters) incurred by the Underwriters in connection with their investigation, preparing to market and marketing the Securities or in contemplation of performing their obligations hereunder. The Selling Stockholder shall not in any event be liable to any of the Underwriters for loss of anticipated profits from the transactions covered by this Agreement.

(iii) The Option Shares to be sold by such Selling Stockholder, represented by the certificates on deposit with the Custodian pursuant to the IPA and Custody Agreement of such Selling Stockholder, are subject to the interest of the several Underwriters and the other Selling Stockholders, if any; the arrangements made for such custody are, except as specifically provided in the IPA and Custody Agreement, irrevocable; and the obligations of such Selling Stockholder hereunder shall not be terminated, except as provided in this Agreement or in the IPA and Custody Agreement, by any act of such Selling Stockholder, by operation of law, whether by the liquidation, dissolution or merger of such Selling Stockholder, by the death of such Selling Stockholder, or by the occurrence of any other event. If any Selling Stockholder should liquidate, dissolve or be a party to a merger or if any other such event should occur before the delivery of the Option Shares hereunder, certificates for the Option Shares deposited with the Custodian shall be delivered by the Custodian in accordance with the terms and conditions of this Agreement as if such liquidation, dissolution, merger or other event had not occurred, whether or not the Custodian shall have received notice thereof.

Such Selling Stockholder will not, without the prior written consent of the Lead Managers during the Lock-Up Period, offer for sale, sell, contract to sell, pledge, grant any option for the sale of, enter into any transaction which is designed to, or might reasonably be expected to, result in disposition (whether by actual disposition or effective economic disposition due to cash settlement or otherwise) or otherwise dispose of, directly or indirectly (or publicly

disclose the intention to make any such offer, sale, pledge, grant, or other disposition), any Common Stock or any securities convertible into or exchangeable for, or any options or rights to purchase or acquire, Common Stock, except to the Underwriters pursuant to this Agreement. In addition, each Selling Stockholder agrees that, without the prior written consent of the Lead Managers, it will not, during the Lock-Up Period, make any demand for or exercise any right with respect to, the registration of any shares of Common Stock or any security convertible into or exercisable or exchangeable for shares of Common Stock. If (1) during the period that begins on the date that is 18 calendar days before the last day of the Lock-Up Period and ends on the last day of the Lock-Up Period, (a) the Company issues an earnings release, (b) the Company publicly announces material news or (c) a material event relating to the Company occurs; or (2) prior to the expiration of the Lock-Up Period, the Company announces that it will release earnings results during the 16-day period beginning on the last day of the Lock-Up Period, then the restrictions in this Agreement, unless otherwise waived by the Lead Managers in writing, shall continue to apply until the expiration of the date that is 18 calendar days after the date on which (a) the Company issues the earnings release, (b) the Company publicly announces material news or (c) a material event relating to the Company occurs. Any shares of Common stock received upon exercise of options granted to a Selling Stockholder will also be subject to this clause (iv). The restrictions on transfers of this clause (iv), however, will not apply to any shares of Common Stock acquired by the Selling Stockholder in the open market. A transfer of shares of Common Stock in connection with a bona fide gift or to a family member or trust may be made, provided the transferee agrees to be bound in writing by the terms of this Agreement.

(iv) Such Selling Stockholder has not taken and will not take, directly or indirectly, any action designed to or which might reasonably be expected to cause or result in stabilization or manipulation of the price of any security of the Company to facilitate the sale or resale of the Securities, and has not effected any sales of Common Stock which, if effected by the Company, would be required to be disclosed in response to Item 701 of Regulation S-K.

(v) Such Selling Stockholder shall immediately notify you if any event occurs, or of any change in information relating to such Selling Stockholder or the Company or any new information relating to the Company or relating to any matter stated in the Time of Sale Disclosure Package or in the Prospectus or any supplement thereto or any Issuer General Free-Writing Prospectus, which results in the Time of Sale Disclosure Package or in the Prospectus (as amended or supplemented) or any Issuer General Free-Writing Prospectus including an untrue statement of a material fact or omitting to state any material fact necessary to make the statements therein, in light of the circumstances under which they were made, not misleading.

(vi) Such Selling Stockholder shall deliver to the Custodian or the Representatives, as appropriate, prior to the First Closing Date, a properly completed and executed United States Treasury Department Form W-9 (or other applicable form or statement specified by Treasury Department regulations in lieu thereof).

(vii) Such Selling Stockholder represents and agrees that, unless it obtains the prior written consent of the Lead Managers, and each Underwriter severally represents and agrees that, unless he, she or it obtains the prior written consent of the Company and the Lead Managers, he, she or it has not made and will not make any offer relating to the Securities that would constitute an "issuer free writing prospectus," as defined in Rule 433, or that would otherwise constitute a "free writing prospectus," as defined in Rule 405, required to be filed with the Commission; provided that the prior written consent of the parties hereto shall be deemed to have been given in respect of the free writing prospectuses included in Schedule III. Such Selling Stockholder represents that he, she or it has treated or agrees that

he, she or it will treat each Permitted Free Writing Prospectus as an "issuer free writing prospectus," as defined in Rule 433, and has complied and will comply with the requirements of Rule 433 applicable to any Permitted Free Writing Prospectus, including timely Commission filing where required, legending and record keeping. Such Selling Stockholder represents that he, she or it has satisfied and agrees that he, she or it will satisfy the conditions in Rule 433 to avoid a requirement to file with the Commission any electronic road show.

5. Conditions of Underwriters' Obligations. The obligations of the several Underwriters hereunder are subject to the accuracy, as of the date hereof and at each of the First Closing Date and the Second Closing Date (as if made at such Closing Date), of and compliance with all representations, warranties and agreements of the Company and the Selling Stockholders contained herein, to the performance by the Company and the Selling Stockholders of their obligations hereunder and to the following additional conditions:

(a) The Registration Statement shall have become effective not later than 5:00 p.m., Central time, on the date of this Agreement, or such later time and date as you, as Representatives of the several Underwriters, shall approve and all filings required by Rules 424, 430A and 433 shall have been timely made (without reliance on Rule 424(b)(8) or Rule 164(b)); no stop order suspending the effectiveness of the Registration Statement or any part thereof or any amendment thereof, nor suspending or preventing the use of the Time of Sale Disclosure Package, the Prospectus or any Issuer Free Writing Prospectus shall have been issued; no proceedings for the issuance of such an order shall have been initiated or threatened; and any request of the Commission for additional information (to be included in the Registration Statement, the Time of Sale Disclosure Package, the Prospectus, any Issuer Free Writing Prospectus or otherwise) shall have been complied with to your satisfaction.

(b) No Underwriter shall have advised the Company that (i) the Registration Statement, or any amendment thereof or supplement thereof contains an untrue statement of a material fact which, in your opinion, is material, or omits to state a material fact which, in your opinion, is required to be stated therein or necessary to make the statements therein not misleading, or (ii) the Time of Sale Disclosure Package or the Prospectus, or any amendment thereof or supplement thereto, or any Issuer Free Writing Prospectus contains an untrue statement of fact which, in your opinion, is material, or omits to state a fact which, in your opinion, is material and is required to be stated therein or necessary to make the statements therein, in light of the circumstances under which they are made, not misleading.

(c) Except as contemplated in the Time of Sale Disclosure Package and in the Prospectus, the Company has not (i) since the date of the latest audited financial statements included in the Time of Sale Disclosure Package and the Prospectus, has sustained any material loss or interference with its business or properties from fire, explosion, flood, hurricane, accident or other calamity, whether or not covered by insurance, or from any labor dispute or any legal or governmental proceeding and (ii) subsequent to the respective dates as of which information is given in the Time of Sale Disclosure Package, shall have incurred any material liabilities or obligations, direct or contingent, or entered into any material transactions, or declared or paid any dividends or made any distribution of any kind with respect to its capital stock; and there shall not have been any change in the capital stock (other than a change in the number of outstanding shares of Common Stock due to the issuance of shares upon the exercise of outstanding options or warrants), or any material change in the short-term or long-term debt of the Company, or any issuance of options, warrants, convertible securities or other rights to purchase the capital stock of the Company, or any Material Adverse Change or any development involving a prospective Material Adverse Change (whether or not arising in the ordinary course of business), that, in your judgment, makes it impractical or inadvisable to offer or deliver the Securities on the terms and in the manner contemplated in the Time of Sale Disclosure Package and in the Prospectus.

(d) On or after the Time of Sale (i) no downgrading shall have occurred in the rating accorded the Company's debt securities or preferred stock, if any, by any "nationally recognized statistical organization," as that term is defined by the Commission for purposes of Rule 436(g)(2) under the Act, and (ii) no such organization shall have publicly announced that it has under surveillance or review, with possible negative implications, its rating of any of the Company's debt securities or preferred stock, if any;

(e) On each Closing Date, there shall have been furnished to you, as Representatives of the several Underwriters, the opinion of ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ & ▇▇▇▇▇▇, P.C., counsel for the Company, dated such Closing Date and addressed to you, in substantially the form annexed hereto as Exhibit B-1.

(f) On each Closing Date, there shall have been furnished to you, as Representatives of the several Underwriters, the opinion of ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ & ▇▇▇▇▇▇, P.C., special intellectual property counsel for the Company, dated such Closing Date and addressed to you, in substantially the form annexed hereto as Exhibit B-2.

(g) On the Second Closing Date, there shall have been furnished to you, as Representatives of the several Underwriters, the opinion of [ ], counsel for the Selling Stockholders, dated such Second Closing Date and addressed to you, in substantially the form annexed hereto as Exhibit B-3.

(h) On each Closing Date, there shall have been furnished to you, as Representatives of the several Underwriters, such opinion or opinions from ▇▇▇▇▇▇ & ▇▇▇▇▇▇▇ LLP, counsel for the several Underwriters, dated such Closing Date and addressed to you, with respect to the formation of the Company, the validity of the Securities, the Registration Statement, the Time of Sale Disclosure Package or the Prospectus and other related matters as you reasonably may request, and such counsel shall have received such papers and information as they request to enable them to pass upon such matters.

(i) On the date of this Agreement and on each Closing Date you, as Representatives of the several Underwriters, shall have received a letter of Ernst & Young LLP, dated such date and addressed to you, confirming that they are independent public accountants within the meaning of the Act and are in compliance with the applicable requirements relating to the qualifications of accountants under Rule 2-01 of Regulation S-X of the Commission, and stating, as of the date of such letter (or, with respect to matters involving changes or developments since the respective dates as of which specified financial information is given in the Time of Sale Disclosure Package, as of a date not prior to the date hereof or more than five days prior to the date of such letter), the conclusions and findings of said firm with respect to the financial information and other matters covered by its letter delivered to you concurrently with the execution of this Agreement, and the effect of the letter so to be delivered on such date shall be to confirm the conclusions and findings set forth in such prior letter.

(j) On each Closing Date, there shall have been furnished to you, as Representatives of the Underwriters, a certificate, dated such Closing Date and addressed to you, signed by the chief executive officer and by the chief financial officer of the Company, to the effect that:

(i) The representations and warranties of the Company in this Agreement are true and correct, in all material respects, as if made at and as of such Closing Date, and the Company has complied with all the agreements and satisfied all the conditions on its part to be performed or satisfied at or prior to such Closing Date;

(ii) No stop order or other order suspending the effectiveness of the Registration Statement or any part thereof or any amendment thereof or the qualification of the Securities for offering or sale, nor suspending or preventing the use of the Time of Sale Disclosure

Package, the Prospectus or any Issuer Free Writing Prospectus, has been issued, and no proceeding for that purpose has been instituted or, to the best of their knowledge, is contemplated by the Commission or any state or regulatory body;

(iii) The signers of said certificate have carefully examined the Registration Statement, the Time of Sale Disclosure Package and the Prospectus, and any amendments thereof or supplements thereto, and (A) each part of the Registration Statement and the Prospectus, and any amendments thereof or supplements thereto contain, and contained when such part of the Registration Statement, or any amendment thereof, became effective, all statements and information required to be included therein, the Registration Statement, or any amendment thereof, does not contain and did not contain when such part of the Registration Statement, or any amendment thereof, became effective, any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein not misleading, and the Prospectus, as amended or supplemented, does not include and did not include as of its date or the time of first use within the meaning of the Rules and Regulations, any untrue statement of material fact or omit to state and did not omit to state as of its date or the time of first use within the meaning of the rules and Regulations a material fact necessary to make the statements therein, in light of the circumstances under which they were made, not misleading, (B) neither (1) the Time of Sale Disclosure Package nor (2) any individual Issuer Limited-Use Free Writing Prospectus, when considered together with the Time of Sale Disclosure Package, include, nor included as of the Time of Sale any untrue statement of a material fact or omits, or omitted as of the Time of Sale, to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading, (C) since the Time of Sale, there has occurred no event required to be set forth in an amended or supplemented prospectus which has not been so set forth, (D) subsequent to the respective dates as of which information is given in the Time of Sale Disclosure Package, the Company has not incurred any material liabilities or obligations, direct or contingent, or entered into any material transactions, not in the ordinary course of business, or declared or paid any dividends or made any distribution of any kind with respect to its capital stock, and except as disclosed in the Time of Sale Disclosure Package and in the Prospectus, there has not been any change in the capital stock (other than a change in the number of outstanding shares of Common Stock due to the issuance of shares upon the exercise of outstanding options or warrants), or any material change in the short-term or long-term debt, or any issuance of options, warrants, convertible securities or other rights to purchase the capital stock, of the Company, or any Material Adverse Change or any development involving a prospective Material Adverse Change (whether or not arising in the ordinary course of business), and (E) except as stated in the Time of Sale Disclosure Package and in the Prospectus, there is not pending, or, to the knowledge of the Company, threatened, any action, suit or proceeding to which the Company is a party before or by any court or governmental agency, authority or body, or any arbitrator, which might result in any Material Adverse Change; and

(iv) The Company confirms that it intends to apply the net proceeds from the sale of Securities to be sold by it hereunder for the purposes set forth in the Time of Sale Disclosure Package and in the Prospectus.

(k) The Underwriters shall have received the Lock-Up Agreements referenced in Section 4(a)(xi) from holders of at least 99% of the outstanding stock (on an as-converted basis) as of the date hereof.

(l) On the Second Closing Date, there shall have been furnished to you, as Representatives of the several Underwriters, a certificate or certificates, dated such Second Closing Date and addressed to you, signed by each of the Selling Stockholders or either of such Selling Stockholder's

Attorneys-in-Fact to the effect that the representations and warranties of such Selling Stockholder contained in this Agreement are true and correct as if made at and as of such Second Closing Date, and that such Selling Stockholder has complied with all the agreements and satisfied all the conditions on such Selling Stockholder's part to be performed or satisfied at or prior to such Second Closing Date.

(m) The Company shall have furnished to you and counsel for the Underwriters such additional documents, certificates and evidence as you or they may have reasonably requested.

(n) The Securities shall have been approved for inclusion on the Nasdaq Global Market, subject only to official notice of issuance.

(o) The NASD shall have confirmed that it has not raised any objection with respect to the fairness and reasonableness of the underwriting terms and arrangements for the offering of the Securities.

(p) At each Closing Date, counsel for the Underwriters shall have been furnished or it shall have been made available to the Underwriters such information, certificates and documents as they may reasonably request for the purpose of enabling them to pass upon the issuance and sale of the Securities as contemplated herein and related proceedings, or to evidence the accuracy of any of the representations or warranties, or the fulfillment of any of the conditions, herein contained, or otherwise in connection with the offering of the Securities contemplated hereby.

All such opinions, certificates, letters and other documents will be in compliance with the provisions hereof only if they are reasonably satisfactory in form and substance you and counsel for the Underwriters. The Company will furnish or make available to you such conformed copies of such opinions, certificates, letters and other documents as you shall reasonably request.

6. Indemnification and Contribution.

(a) The Company agrees to indemnify and hold harmless each Underwriter, its affiliates, directors and officers and each person, if any, who controls such Underwriter within the meaning of Section 15 of the Act or Section 20 of the Exchange Act (each an "Indemnified Person"), from and against any losses, claims, damages or liabilities, joint or several, to which such Underwriter may become subject, under the Act or otherwise (including in settlement of any litigation if such settlement is effected with the written consent of the Company (not to be unreasonably withheld, delayed or conditioned)), insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon an untrue statement or alleged untrue statement of a material fact contained in the Registration Statement, including the information deemed to be a part of the Registration Statement at the time of effectiveness and at any subsequent time pursuant to Rules 430A and 430C, if applicable, any Preliminary Prospectus, the Time of Sale Disclosure Package, the Prospectus, or any amendment or supplement thereto, any Issuer Free Writing Prospectus or in any materials or information provided to investors by, or with the approval of, the Company in connection with the marketing of the offering of the Common Stock ("Marketing Materials"), including any roadshow or investor presentations made to investors by the Company (whether in person or electronically) or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, and will reimburse each Underwriter for any legal or other expenses reasonably incurred by it in connection with investigating or defending against such loss, claim, damage, liability or action; provided, however, that the Company shall not be liable in any such case to the extent that any such loss, claim, damage, liability or action arises out of or is based upon an untrue statement or alleged untrue statement or omission or alleged omission made in the Registration Statement, any Preliminary Prospectus, the Time of Sale Disclosure Package, the Prospectus, or any such amendment or supplement or in any Marketing Materials or any Issuer

Free Writing Prospectus, in reliance upon and in conformity with information provided in writing to the Company by the Representatives, or by any Underwriter through the Representatives, specifically for use in the preparation thereof, it being understood and agreed that the only such information furnished by the Representatives to the Company consists of the information described in subsection (g) below.

In addition to its other obligations under this Section 6(a), the Company agrees that, as an interim measure during the pendency of any claim, action, investigation, inquiry or other proceeding arising out of or based upon any statement or omission, or any alleged statement or omission, described in this Section 6(a), it will reimburse each Underwriter on a monthly basis for all reasonable legal fees or other expenses incurred in connection with investigating or defending any such claim, action, investigation, inquiry or other proceeding, notwithstanding the absence of a judicial determination as to the propriety and enforceability of the Company's obligation to reimburse the Underwriters for such expenses and the possibility that such payments might later be held to have been improper by a court of competent jurisdiction. To the extent that any such interim reimbursement payment is so held to have been improper by reason of such payment resulting from an action in respect of which the Underwriters are not due indemnification or contribution hereunder, the Underwriter that received such payment shall promptly return it to the party or parties that made such payment, together with interest, compounded daily, determined on the basis of the prime rate (or other commercial lending rate for borrowers of the highest credit standing) announced from time to time by [ ] (the "Prime Rate"). Any such interim reimbursement payments which are not made to an Underwriter within 30 days of a request for reimbursement shall bear interest at the Prime Rate from the date of such request. This indemnity agreement shall be in addition to any liabilities which the Company may otherwise have.

(b) Each of the Selling Stockholders agrees, severally and not jointly, to indemnify and hold harmless each Underwriter, its affiliates, directors and officers and each person, if any, who controls such Underwriter within the meaning of Section 15 of the Act or Section 20 of the Exchange Act, from and against any losses, claims, damages or liabilities, joint or several, to which such Underwriter may become subject, under the Act or otherwise (including in settlement of any litigation if such settlement is effected with the written consent of such Selling Stockholder), insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon an untrue statement or alleged untrue statement of a material fact contained in the Registration Statement, including the information deemed to be a part of the Registration Statement at the time of effectiveness and at any subsequent time pursuant to Rules 430A and 430C, if applicable, any Preliminary Prospectus, the Time of Sale Disclosure Package, the Prospectus, or any amendment or supplement thereto, any Issuer Free Writing Prospectus or in any Marketing Materials, including any road show or investor presentations made to investors by the Company (whether in person or electronically) or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, and will reimburse each Underwriter for any legal or other expenses reasonably incurred by it in connection with investigating or defending against such loss, claim, damage, liability or action; provided, however, that each of the Selling Stockholders shall only be liable in any such case to the extent that any such loss, claim, damage, liability or action arises out of or is based upon an untrue statement or alleged untrue statement or omission or alleged omission made in the Registration Statement, any Preliminary Prospectus, the Time of Sale Disclosure Package, the Prospectus, or any such amendment or supplement, any Issuer Free Writing Prospectus or in any Marketing Materials in reliance upon and in conformity with written information concerning such Selling Stockholder furnished to the Company by or on behalf of such Selling Stockholder expressly for inclusion therein; and provided further, that no Selling Stockholder shall be liable in any such case to the extent that any such loss, claim, damage, liability or action arises out of or is based upon an untrue statement or alleged untrue statement or omission or

alleged omission made in the Registration Statement, any Preliminary Prospectus, the Time of Sale Disclosure Package, the Prospectus, or any such amendment or supplement, any Issuer Free Writing Prospectus or in any Marketing Materials, in reliance upon and in conformity with information provided in writing to the Company by you, or by any Underwriter through you, specifically for use in the preparation thereof. The indemnity agreement set forth herein is not exclusive of any agreement the Company may have with the Selling Stockholders relating to indemnification, and nothing contained in this Agreement shall affect any obligation or liability the Company may have to one or more of the Selling Stockholders, or one or more of the Selling Stockholders may have to the Company, pursuant to other agreements.

In addition to its other obligations under this Section 6(b), each Selling Stockholder, severally and not jointly, agrees that, as an interim measure during the pendency of any claim, action, investigation, inquiry or other proceeding arising out of or based upon any statement or omission, or any alleged statement or omission, described in this Section 6(b), it will reimburse each Underwriter on a monthly basis for all reasonable legal fees or other expenses incurred in connection with investigating or defending any such claim, action, investigation, inquiry or other proceeding, notwithstanding the absence of a judicial determination as to the propriety and enforceability of the Selling Stockholder's obligation to reimburse the Underwriters for such expenses and the possibility that such payments might later be held to have been improper by a court of competent jurisdiction. To the extent that any such interim reimbursement payment is so held to have been improper, the Underwriter that received such payment shall promptly return it to the party or parties that made such payment, together with interest, compounded daily, determined on the basis of the Prime Rate. Any such interim reimbursement payments which are not made to an Underwriter within 30 days of a request for reimbursement shall bear interest at the Prime Rate from the date of such request. This indemnity agreement shall be in addition to any liabilities which the Selling Stockholders may otherwise have.

(c) Each Underwriter will indemnify and hold harmless the Company, its affiliates, directors and officers and each person, if any, who controls the Company within the meaning of Section 15 of the Act and Section 20 of the Exchange Act, and each Selling Stockholder and its affiliates, directors and officers and each person, if any, who controls such Selling Stockholder within the meaning of Section 15 of the Act or Section 20 of the Exchange Act, from and against any losses, claims, damages or liabilities to which the Company or the Selling Stockholders may become subject, under the Act or otherwise (including in settlement of any litigation, if such settlement is effected with the written consent of such Underwriter), insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon an untrue statement or alleged untrue statement of a material fact contained in the Registration Statement, any Preliminary Prospectus, the Time of Sale Disclosure Package, the Prospectus, or any amendment or supplement thereto, or any Issuer Free Writing Prospectus or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, in each case to the extent, but only to the extent, that such untrue statement or alleged untrue statement or omission or alleged omission was made in the Registration Statement, any Preliminary Prospectus, the Time of Sale Disclosure Package, the Prospectus, or any such amendment or supplement, or any Issuer Free Writing Prospectus in reliance upon and in conformity with information provided in writing to the Company by you, or by such Underwriter through you, specifically for use in the preparation thereof, and will reimburse the Company and the Selling Stockholders for any legal or other expenses reasonably incurred by the Company or any such Selling Stockholder in connection with investigating or defending against any such loss, claim, damage, liability or action, it being understood and agreed that the only such information furnished by the Representatives to the Company consists of the information described in subsection (g) below.

(d) Promptly after receipt by an indemnified party under subsection (a) or (b) above of notice of the commencement of any action, such indemnified party shall, if a claim in respect thereof is to be made against the indemnifying party under such subsection, notify the indemnifying party in writing of the commencement thereof; but the omission so to notify the indemnifying party shall not relieve the indemnifying party from any liability that it may have to any indemnified party except to the extent such indemnifying party has been materially prejudiced by such failure. In case any such action shall be brought against any indemnified party, and it shall notify the indemnifying party of the commencement thereof, the indemnifying party shall be entitled to participate in, and, to the extent that it shall wish, jointly with any other indemnifying party similarly notified, to assume the defense thereof, with counsel reasonably satisfactory to such indemnified party, and after notice from the indemnifying party to such indemnified party of the indemnifying party's election so to assume the defense thereof, the indemnifying party shall not be liable to such indemnified party under such subsection for any legal or other expenses subsequently incurred by such indemnified party in connection with the defense thereof other than reasonable costs of investigation; provided, however, that if, in the sole judgment of the Representatives, it is advisable for the Underwriters to be represented as a group by separate counsel, the Representatives shall have the right to employ a single counsel to represent the Representatives and all Underwriters who may be subject to liability arising from any claim in respect of which indemnity may be sought by the Underwriters under subsection (a) or (b) of this Section 6, in which event the reasonable fees and expenses of such separate counsel shall be borne by the indemnifying party or parties and reimbursed to the Underwriters as incurred (in accordance with the provisions of the second paragraph in subsection (a) above or the second paragraph in subsection (b) above). An indemnifying party shall not be obligated under any settlement agreement relating to any action under this Section 6 to which it has not agreed in writing. In addition, no indemnifying party shall, without the prior written consent of the indemnified party, effect any settlement of any pending or threatened proceeding unless such settlement includes an unconditional release of such indemnified party for all liability on claims that are the subject matter of such proceeding and does not include a statement as to or an admission of fault, culpability or any failure to act by or on behalf of the indemnified party.

(e) If the indemnification provided for in this Section 6 is unavailable or insufficient to hold harmless an indemnified party under subsection (a), (b) or (c) above, then each indemnifying party shall contribute to the amount paid or payable by such indemnified party as a result of the losses, claims, damages or liabilities referred to in subsection (a) or (b) above, (i) in such proportion as is appropriate to reflect the relative benefits received by the Company and the Selling Stockholders on the one hand and the Underwriters on the other from the offering of the Securities or (ii) if the allocation provided by clause (i) above is not permitted by applicable law, in such proportion as is appropriate to reflect not only the relative benefits referred to in clause (i) above but also the relative fault of the Company and the Selling Stockholders on the one hand and the Underwriters on the other in connection with the statements or omissions that resulted in such losses, claims, damages or liabilities, as well as any other relevant equitable considerations. The relative benefits received by the Company and the Selling Stockholders on the one hand and the Underwriters on the other shall be deemed to be in the same proportion as the total net proceeds from the offering (before deducting expenses) received by the Company and the Selling Stockholders bear to the total underwriting discounts and commissions received by the Underwriters, in each case as set forth in the table on the cover page of the Prospectus. The relative fault shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by the Company and the Selling Stockholders or the Underwriters and the parties' relevant intent, knowledge, access to information and opportunity to correct or prevent such untrue statement or omission. The Company, the Selling Stockholders and the Underwriters agree that it would not be

just and equitable if contributions pursuant to this subsection (e) were to be determined by pro rata allocation (even if the Underwriters were treated as one entity for such purpose) or by any other method of allocation which does not take account of the equitable considerations referred to in the first sentence of this subsection (e). The amount paid by an indemnified party as a result of the losses, claims, damages or liabilities referred to in the first sentence of this subsection (e) shall be deemed to include any legal or other expenses reasonably incurred by such indemnified party in connection with investigating or defending against any action or claim which is the subject of this subsection (e). Notwithstanding the provisions of this subsection (e), no Underwriter shall be required to contribute any amount in excess of the amount by which the total price at which the Securities underwritten by it and distributed to the public were offered to the public exceeds the amount of any damages that such Underwriter has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission. No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation. The Underwriters' obligations in this subsection (e) to contribute are several in proportion to their respective underwriting obligations and not joint.

(f) The obligations of the Company and the Selling Stockholders under this Section 6 shall be in addition to any liability which the Company and the Selling Stockholders may otherwise have and shall extend, upon the same terms and conditions, to each person, if any, who controls any Underwriter within the meaning of the Act; and the obligations of the Underwriters under this Section 6 shall be in addition to any liability that the respective Underwriters may otherwise have and shall extend, upon the same terms and conditions, to each director of the Company (including any person who, with his consent, is named in the Registration Statement as about to become a director of the Company), to each officer of the Company who has signed the Registration Statement and to each person, if any, who controls the Company or any Selling Stockholder within the meaning of the Act. Notwithstanding anything herein to the contrary, in no event shall any Selling Stockholder be liable under the provisions of this Section 6 for any amount in excess of the aggregate amount of proceeds such Selling Stockholder received, after underwriting discounts and commissions, from the sale of the Securities pursuant to this Agreement.

(g) The Underwriters severally confirm and the Company and each Selling Stockholder acknowledges that the statements with respect to the public offering of the Securities by the Underwriters set forth in [ ], the Time of Sale Disclosure Package and in the Prospectus constitute the only information concerning such Underwriters furnished in writing to the Company by or on behalf of the Underwriters specifically for inclusion in the Registration Statement, any Preliminary Prospectus, the Time of Sale Disclosure Package, the Prospectus or any Issuer Free Writing Prospectus.

(h) In connection with the offer and sale of the Directed Stock, the Company agrees, promptly upon a request in writing, to indemnify and hold harmless the Underwriters from and against any and all losses, liabilities, claims, damages and expenses incurred by them as a result of the failure of the Directed Stock Participants to affirmatively reconfirm the Directed Stock for purchase as of the date of this Agreement or to pay for and accept delivery of the Directed Stock by the end of the First Closing Date.

7. Representations and Agreements to Survive Delivery. All representations, warranties, and agreements of the Company and the Selling Stockholders herein or in certificates delivered pursuant hereto, and the agreements of the several Underwriters, the Company and the Selling Stockholders contained in Section 6 hereof, shall remain operative and in full force and effect regardless of any investigation made by or on behalf of any Underwriter or any controlling person thereof, or the Company or any of its officers, directors, or controlling persons, or any Selling Stockholders or any controlling person thereof, and shall survive delivery of, and payment for, the Securities to and by the Underwriters hereunder.

8. Substitution of Underwriters.

(a) If any Underwriter or Underwriters shall fail to take up and pay for the amount of Firm Shares agreed by such Underwriter or Underwriters to be purchased hereunder, upon tender of such Firm Shares in accordance with the terms hereof, and the amount of Firm Shares not purchased does not aggregate more than 10% of the total amount of Firm Shares set forth in Schedule I hereto, the remaining Underwriters shall be obligated to take up and pay for (in proportion to their respective underwriting obligations hereunder as set forth in Schedule I hereto except as may otherwise be determined by you) the Firm Shares that the withdrawing or defaulting Underwriters agreed but failed to purchase.

(b) If any Underwriter or Underwriters shall fail to take up and pay for the amount of Firm Shares agreed by such Underwriter or Underwriters to be purchased hereunder, upon tender of such Firm Shares in accordance with the terms hereof, and the amount of Firm Shares not purchased aggregates more than 10% of the total amount of Firm Shares set forth in Schedule I hereto, and arrangements satisfactory to you for the purchase of such Firm Shares by other persons are not made within 36 hours thereafter, this Agreement shall terminate. In the event of any such termination neither the Company nor any Selling Stockholder shall be under any liability to any Underwriter (except to the extent provided in Section 4(a)(viii), Section 4(b)(ii) and Section 6 hereof) nor shall any Underwriter (other than an Underwriter who shall have failed, otherwise than for some reason permitted under this Agreement, to purchase the amount of Firm Shares agreed by such Underwriter to be purchased hereunder) be under any liability to the Company and the Selling Stockholders (except to the extent provided in Section 6 hereof).

If Firm Shares to which a default relates are to be purchased by the non-defaulting Underwriters or by any other party or parties, the Representatives or the Company shall have the right to postpone the First Closing Date for not more than seven business days in order that the necessary changes in the Registration Statement, in the Time of Sale Disclosure Package, in the Prospectus or in any other documents, as well as any other arrangements, may be effected. As used herein, the term "Underwriter" includes any person substituted for an Underwriter under this Section 8.

9. Effective Date of this Agreement and Termination.

(a) This Agreement shall become effective at 10:00 a.m., Central time, on the first full business day following the effective date of the Registration Statement, or at such earlier time after the effective time of the Registration Statement as you in your discretion shall first release the Securities for sale to the public; provided, that if the Registration Statement is effective at the time this Agreement is executed, this Agreement shall become effective at such time as you in your discretion shall first release the Securities for sale to the public. For the purpose of this Section, the Securities shall be deemed to have been released for sale to the public upon release by you of an electronic communication authorizing commencement of the offering the Securities for sale by the Underwriters or other securities dealers. By giving notice as hereinafter specified before the time this Agreement becomes effective, you, as Representatives of the several Underwriters, or the Company, may prevent this Agreement from becoming effective without liability of any party to any other party, except that the provisions of Section 4(a)(viii), Section 4(b)(ii) and Section 6 hereof shall at all times be effective.

(b) You, as Representatives of the several Underwriters, shall have the right to terminate this Agreement by giving notice as hereinafter specified at any time at or prior to the First Closing Date, and the option referred to in Section 3(b), if exercised, may be cancelled at any time prior to the Second Closing Date, if (i) the Company shall have failed, refused or been unable, at or prior to such Closing Date, to perform any agreement on its part to be performed hereunder, (ii) any other condition of the Underwriters' obligations hereunder is not fulfilled, (iii) trading on the Nasdaq Global Market, the New York Stock Exchange or the American Stock Exchange shall

have been wholly suspended, (iv) trading in the Company's securities on the Nasdaq Global Market shall have been suspended or materially limited, (v) minimum or maximum prices for trading shall have been fixed, or maximum ranges for prices for securities shall have been required, on the Nasdaq Global Market, the New York Stock Exchange or the American Stock Exchange, by such Exchange or by order of the Commission or any other Governmental Authority, (vi) a banking moratorium shall have been declared by federal or state authorities, (vii) any downgrading shall have occurred in the Company's corporate credit rating or the rating accorded the Company's debt securities or preferred stock by any "nationally recognized statistical rating organization" (as defined for purposes of Rule 436(g) under the Act) or any such organization shall have publicly announced that it has under surveillance or review, with possible negative implications, its rating of any of the Company's debt securities, (viii) in the judgment of the Lead Managers, there shall have occurred any Material Adverse Change or (ix) there shall have occurred any outbreak or escalation of hostilities or any change in financial markets or any calamity or crisis that, in the judgment of the Lead Managers, is material and adverse and makes it impractical or inadvisable to proceed with the completion of the sale of and payment for the Securities. Any such termination shall be without liability of any party to any other party except that the provisions of Section 4(a)(viii), Section 4(b)(ii) and Section 6 hereof shall at all times be effective.

(c) If you elect to prevent this Agreement from becoming effective or to terminate this Agreement as provided in this Section, the Company and an Attorney-in-Fact, on behalf of the Selling Stockholders, shall be notified promptly by you by telephone, confirmed by letter. If the Company elects to prevent this Agreement from becoming effective, you and an Attorney-in-Fact, on behalf of the Selling Stockholders, shall be notified by the Company by telephone, confirmed by letter.

10. Default by the Company. If the Company shall fail at the First Closing Date to sell and deliver the number of Securities which it is obligated to sell hereunder, then this Agreement shall terminate without any liability on the part of any non-defaulting party.

No action taken pursuant to this Section shall relieve the Company from liability, if any, in respect of such default.

11. Notices. Except as otherwise provided herein, all communications hereunder shall be in writing and, if to the Underwriters, shall be mailed or delivered to the Representatives c/o ▇▇▇▇▇ ▇▇▇▇▇▇▇ & Co., ▇▇▇ ▇▇▇▇▇▇▇▇ ▇▇▇▇, ▇▇▇▇▇▇▇▇▇▇▇, ▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇ and c/▇ ▇▇▇▇▇▇▇▇▇ & Company, Inc., ▇▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇ ▇▇▇▇, ▇▇▇ ▇▇▇▇ ▇▇▇▇▇, attention: General Counsel, except that notices given to an Underwriter pursuant to Section 6 hereof shall be sent to such Underwriter at the address stated in the Underwriters' Questionnaire furnished by such Underwriter in connection with this offering, with a copy to ▇▇▇▇▇▇ & ▇▇▇▇▇▇▇ LLP, ▇▇▇▇▇ ▇▇▇▇ ▇▇▇▇▇ ▇▇▇▇▇, ▇▇▇▇▇ ▇▇▇, ▇▇▇ ▇▇▇▇▇, ▇▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇, Attention: ▇▇▇▇▇ ▇. ▇▇▇▇▇, Esq.; and if to the Company, shall be mailed or delivered to it at ▇▇▇▇▇ ▇▇▇▇▇▇▇▇ ▇▇▇▇▇▇ ▇▇▇▇, ▇▇▇▇▇ ▇, ▇▇▇ ▇▇▇▇▇, ▇▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇, Attention: ▇▇▇▇▇▇▇ ▇▇▇▇▇, Ph.D. and ▇▇▇▇ ▇▇▇▇▇▇, with a copy to ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ & ▇▇▇▇▇▇, P.C., ▇▇▇▇▇ ▇▇ ▇▇▇▇▇▇ ▇▇▇▇, ▇▇▇▇▇ ▇▇▇, ▇▇▇ ▇▇▇▇▇, ▇▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇ Attention: ▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇, Esq.; if to any of the Selling Stockholders, at the address of the Attorneys-in-Fact as set forth in the Powers of Attorney, or in each case to such other address as the person to be notified may have requested in writing, with a copy to [ ], Attention: [ ]. Any party to this Agreement may change such address for notices by sending to the parties to this Agreement written notice of a new address for such purpose. Any party to this Agreement may change such address for notices by sending to the parties to this Agreement written notice of a new address for such purpose.

12. Persons Entitled to Benefit of Agreement. This Agreement shall inure to the benefit of and be binding upon the parties hereto and their respective successors and assigns and the controlling persons, officers and directors referred to in Section 6. Nothing in this Agreement is intended or shall be

construed to give to any other person, firm or corporation any legal or equitable remedy or claim under or in respect of this Agreement or any provision herein contained. The term "successors and assigns" as herein used shall not include any purchaser, as such purchaser, of any of the Securities from any of the several Underwriters.

13. Absence of Fiduciary Relationship. The Company and each of the Selling Stockholders acknowledge and agree that: (a) the Representatives have been retained solely to act as an underwriter in connection with the sale of the Securities and that no fiduciary, advisory or agency relationship between the Company and such Selling Stockholder, on the one hand, and the Representatives, on the other hand, has been created in respect of any of the transactions contemplated by this Agreement or the IPA and Custody Agreement, as applicable, irrespective of whether the Representatives have advised or are advising the Company or any Selling Stockholder on other matters; (b) the price and other terms of the Securities set forth in this Agreement were established by the Company and the Selling Stockholders following discussions and arms-length negotiations with the Representatives and the Company and such Selling Stockholder is capable of evaluating and understanding and understands and accepts the terms, risks and conditions of the transactions contemplated by this Agreement; (c) he, she or it has been advised that the Representatives and their affiliates are engaged in a broad range of transactions which may involve interests that differ from those of the Company and any of the Selling Stockholders, and that the Representatives have no obligation to disclose such interest and transactions to the Company or the Selling Stockholders by virtue of any fiduciary, advisory or agency relationship; (d) the Company and the Selling Stockholders have been advised that the Representatives are acting, in respect of the transactions contemplated by this Agreement and the IPA and Custody Agreement, as applicable, solely for the benefit of the Representatives and the other Underwriters, and not on behalf of the Company or the Selling Stockholders; (e) the Representatives have not provided any legal, accounting, regulatory, or tax advice with respect to the offering contemplated hereby and the Company and each of the Selling Stockholders has consulted his, her or its own legal, accounting, regulatory and tax advisors to the extent it deemed appropriate; and (f) the Company waives to the fullest extent permitted by law, any claims he, she or it may have against the Representatives for breach of fiduciary duty or alleged breach of fiduciary duty in respect of any of the transactions contemplated by this Agreement or the IPA or Custody Agreement, as applicable, and agrees that the Representatives shall have no liability (whether direct or indirect) to the Company or such Selling Stockholder in respect of such a fiduciary duty claim on behalf of or in right of the Company or such Selling Stockholder, including stockholders, employees or creditors of the Company or such Selling Stockholder, as applicable.

14. Research Analyst Independence. The Company acknowledges that the Underwriters' research analysts and research departments are required to and should be independent from their respective investment banking divisions and are subject to certain regulations and internal policies, and as such Underwriters' research analysts may hold views and make statements or investment recommendations and/or publish research reports with respect to the Company or the offering that differ from the views of their respective investment banking divisions. The Company understand that each of the Underwriters is a full service securities firm and as such from time to time, subject to applicable securities laws, may effect transactions for its own account or the account of its customers and hold long or short positions in debt or equity securities of the companies that may be the subject of the transactions contemplated by this Agreement.

15. Governing Law. This Agreement shall be governed by and construed in accordance with the laws of the State of New York. The Company and each of the Selling Stockholders irrevocably (a) submit to the jurisdictions of any court of the State of New York or the United States District Court for the Southern District of the State of New York for the purpose of any suit, action or other proceeding arising out of this Agreement, or any of the agreements or transactions contemplated by this Agreement, (each, a "Proceeding"), (b) agree that all claims in respect of any Proceeding may be

heard and determined in any such court, (c) waive, to the fullest extent permitted by law, any immunity from jurisdiction of any such court or from any legal process therein, (d) agree not to commence any Proceeding other than in such courts, and (e) waive, to the fullest extent permitted by law, any claim that such Proceeding is brought in an inconvenient forum.

16. Counterparts. This Agreement may be executed in one or more counterparts and, if executed in more than one counterpart, the executed counterparts shall each be deemed to be an original and all such counterparts shall together constitute one and the same instrument.

17. Headings. The headings herein are inserted for convenience of reference only and are not intended to be part of, or to affect the meaning or interpretation of, this Agreement.

18. Time is of the Essence. Time shall be of the essence of this Agreement. As used herein, the term "business day" shall mean any day when the Commission's office in Washington, D.C. is open for business.

[Signature Page Follows]

Please sign and return to the Company the enclosed duplicates of this letter whereupon this letter will become a binding agreement between the Company, the Selling Stockholders and the several Underwriters in accordance with its terms.

		Very truly yours,
		OPTIMER PHARMACEUTICALS, INC.
		By	▇▇▇▇▇▇▇ ▇▇▇▇▇ Chief Executive Officer

		SELLING STOCKHOLDERS
		By	Attorney-in-Fact

Confirmed as of the date first
above mentioned, on behalf of
themselves and the other several
Underwriters named in Schedule I
hereto.

▇▇▇▇▇ ▇▇▇▇▇▇▇ & CO. ▇▇▇▇▇▇▇▇▇ & COMPANY, INC.
	By:	▇▇▇▇▇ ▇▇▇▇▇▇▇ & CO.
	By	Managing Director
	By:	▇▇▇▇▇▇▇▇▇ & COMPANY, INC.
	By	Managing Director

SCHEDULE I

Underwriters

Underwriter		Number of Firm Shares(1)		Number of Option Shares
▇▇▇▇▇ ▇▇▇▇▇▇▇ & Co.
▇▇▇▇▇▇▇▇▇ & Company, Inc.
JMP Securities LLC
▇▇▇▇▇▇ & ▇▇▇▇▇▇▇, LLC




Total

(1): The Underwriters may purchase up to an additional [ ] Option Shares, to the extent the option described in Section 3(b) of the Agreement is exercised, in the proportions and in the manner described in the Agreement.

SCHEDULE II

Selling Stockholders

Name		Maximum Number of Option Shares Subject to Option
Par Pharmaceutical, Inc.








Total

SCHEDULE III

ISSUER GENERAL FREE WRITING PROSPECTUSES

Exhibit A

FORM OF LOCK-UP AGREEMENT

Exhibit A-1

ALTERNATIVE FORM OF LOCK-UP AGREEMENT
(PAR PHARMACEUTICAL, INC.)

Exhibit B-1

FORM OF ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ & ▇▇▇▇▇▇, P.C., LEGAL OPINION

Exhibit B-2

FORM OF ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ & ▇▇▇▇▇▇, P.C.,
INTELLECTUAL PROPERTY OPINION

Exhibit B-3

FORM OF LEGAL OPINION OF COUNSEL TO SELLING STOCKHOLDERS

QuickLinks

Exhibit 1.1

[ ] Shares(1) OPTIMER PHARMACEUTICALS, INC. Common Stock PURCHASE AGREEMENT
SCHEDULE I Underwriters
SCHEDULE II Selling Stockholders
SCHEDULE III ISSUER GENERAL FREE WRITING PROSPECTUSES
Exhibit A FORM OF LOCK-UP AGREEMENT
Exhibit A-1 ALTERNATIVE FORM OF LOCK-UP AGREEMENT (PAR PHARMACEUTICAL, INC.)
Exhibit B-1 FORM OF ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ & ▇▇▇▇▇▇, P.C., LEGAL OPINION
Exhibit B-2 FORM OF ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ & ▇▇▇▇▇▇, P.C., INTELLECTUAL PROPERTY OPINION
Exhibit B-3 FORM OF LEGAL OPINION OF COUNSEL TO SELLING STOCKHOLDERS

] Shares(1) OPTIMER PHARMACEUTICALS, INC. Common Stock PURCHASE AGREEMENT

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