Exhibit 5.1

                                  [LETTERHEAD]

                                                     Dura Pharmaceuticals, Inc.
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                                  July 14, 2000



Dura Pharmaceuticals, Inc.
7475 Lusk Boulevard
San Diego, California  92121

                  Re:      Dura Pharmaceuticals, Inc. Registration Statement on
                           Form S-4 for 6,355,000 Warrants to purchase shares of
                           Common Stock and the shares of Common Stock issuable
                           upon exercise of such Warrants

Ladies and Gentlemen:

                  We have acted as counsel to Dura Pharmaceuticals, Inc., a
Delaware corporation (the "Company"), in connection with the proposed issuance
by the Company of up to 6,355,000 warrants to purchase shares of the Company's
Common Stock (the "Warrants") and shares of the Company's Common Stock issuable
upon exercise of the Warrants (the "Shares") pursuant to the Company's
Registration Statement on Form S-4 (the "Registration Statement") filed with the
Securities and Exchange Commission under the Securities Act of 1933, as amended
(the "Act").

                  This opinion is being furnished in accordance with the
requirements of Item 21(a) of Form S-4 and Item 601(b)(5)(i) of Regulation S-K.

                  We have reviewed the Company's charter documents and the
corporate proceedings taken by the Company in connection with the issuance of
the Warrants and, upon exercise, the Shares. Based on such review, we are of the
opinion that (1) the Warrants have been duly authorized, and if, as and when
issued in accordance with the Registration Statement and the related
prospectus/proxy statement (as amended and supplemented through the date of
issuance) will be legally issued, and fully paid and (2) the Shares have been
duly and validly



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reserved for issuance and, if, as and when issued upon such exercise in
accordance with the terms of the Warrants and the Registration Statement and the
related prospectus/proxy statement, will be legally issued, fully paid and
nonassessable.

                  We consent to the filing of this opinion letter as Exhibit 5.1
to the Registration Statement and to the reference to this firm under the
caption "Legal Matters" in the prospectus which is part of the Registration
Statement. In giving this consent, we do not thereby admit that we are within
the category of persons whose consent is required under Section 7 of the Act,
the rules and regulations of the Securities and Exchange Commission promulgated
thereunder, or Item 509 of Regulation S-K.



                  This opinion letter is rendered as of the date first written
above and we disclaim any obligation to advise you of facts, circumstances,
events or developments which hereafter may be brought to our attention and which
may alter, affect or modify the opinion expressed herein. Our opinion is
expressly limited to the matters set forth above and we render no opinion,
whether by implication or otherwise, as to any other matters relating to the
Company, the Warrants or the Shares.

                                       Very truly yours,
                                       BROBECK, PHLEGER & HARRISON LLP