January 3, 2001 Nastech Pharmaceutical Company Inc. 45 Davids Drive Hauppauge, New York 11788 Attn: Andrew Zinzi Waiver of Section 2.1(f)(ii) of Equity Line of Credit Agreement Dear Mr. Zinzi: Reference is made to the Equity Line of Credit Agreement,...

                                                                  EXHIBIT 2.1(A)

                          Castlebar Enterprises Limited

                                                              January 3, 2001

Nastech Pharmaceutical Company Inc.
00 Xxxxxx Xxxxx
Xxxxxxxxx, Xxx Xxxx 00000
Attn: Xxxxxx Xxxxx

         Waiver of Section 2.1(f)(ii) of Equity Line of Credit Agreement

Dear Xx. Xxxxx:

      Reference is made to the Equity Line of Credit Agreement, dated as of July
11, 2000 (the "Agreement"), between Castlebar Enterprises Limited ("Castlebar")
and Nastech Pharmaceutical Company Inc. ("Nastech"). Pursuant to Section
2.1(f)(ii) of the Agreement, on each date of settlement of a put, Nastech is
obligated to issue to Castlebar a warrant to purchase up to a number of shares
of common stock of Nastech ("Common Stock") equal to 25% of the number of shares
of Common Stock purchased by the Castlebar on such date (defined both in the
Agreement and herein as "Short Term Warrants").

      Castlebar hereby waives Nastech's compliance with Section 2.1(f)(ii) of
the Agreement.

                                  Sincerely,

                                  CASTLEBAR ENTERPRISES LIMITED


                                  By:      /s/  Xxxx Xxxxxxx
                                      ------------------------------------------
                                          Name:  Xxxx Xxxxxxx
                                          Title: Director