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                                                                   EXHBIT 3.1
 
                          CERTIFICATE OF INCORPORATION
 
                                       OF
 
                                  VIVUS, INC.
 
                                   ARTICLE I
 
     The name of the corporation is VIVUS, Inc. (the "Corporation").
 
                                   ARTICLE II
 
     The address of the Corporation's registered office in the State of Delaware
is 1209 Orange Street, City of Wilmington, County of New Castle, Delaware 19801.
The name of its registered agent at such address is The Corporation Trust
Company.
 
                                  ARTICLE III
 
     The purpose of the Corporation is to engage in any lawful act or activity
for which corporations may be organized under the General Corporation Law of
Delaware.
 
                                   ARTICLE IV
 
     The Corporation is authorized to issue two classes of shares of stock to be
designated, respectively, Common Stock, $0.001 par value, and Preferred Stock,
$0.001 par value. The total number of shares that the Corporation is authorized
to issue is 35,000,000 shares. The number of shares of Common Stock authorized
is 30,000,000. The number of shares of Preferred authorized is 5,000,000.
 
     The Preferred Stock may be issued from time to time in one or more series
pursuant to a resolution or resolutions providing for such issue duly adopted by
the board of directors (authority to do so being hereby expressly vested in the
board). The board of directors is further authorized to determine or alter the
rights, preferences, privileges and restrictions granted to or imposed upon any
wholly unissued series of Preferred Stock and to fix the number of shares of any
series of Preferred Stock and the designation of any such series of Preferred
Stock. The board of directors, within the limits and restrictions stated in any
resolution or resolutions of the board of directors originally fixing the number
of shares constituting any series, may increase or decrease (but not below the
number of shares in any such series then outstanding) the number of shares of
any series subsequent to the issue of shares of that series.
 
     The authority of the board of directors with respect to each such class or
series shall include, without limitation of the foregoing, the right to
determine and fix:
 
          (a) the distinctive designation of such class or series and the number
     of shares to constitute such class or series;
 
          (b) the rate at which dividends on the shares of such class or series
     shall be declared and paid, or set aside for payment, whether dividends at
     the rate so determined shall be cumulative or accruing, and whether the
     shares of such class or series shall be entitled to any participating or
     other dividends in addition to dividends at the rate so determined, and if
     so, on what terms;
 
          (c) the right or obligation, if any, of the corporation to redeem
     shares of the particular class or series of Preferred Stock and, if
     redeemable, the price, terms and manner of such redemption;
 
          (d) the special and relative rights and preferences, if any, and the
     amount or amounts per share, which the shares of such class or series of
     Preferred Stock shall be entitled to receive upon any voluntary or
     involuntary liquidation, dissolution or winding up of the Corporation;
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          (e) the terms and conditions, if any, upon which shares of such class
     or series shall be convertible into, or exchangeable for, shares of capital
     stock of any other class or series, including the price or prices or the
     rate or rates of conversion or exchange and the terms of adjustment, if
     any;
 
          (f) the obligation, if any, of the corporation to retire, redeem or
     purchase shares of such class or series pursuant to a sinking fund or fund
     of a similar nature or otherwise, and the terms and conditions of such
     obligation;
 
          (g) voting rights, if any, on the issuance of additional shares of
     such class or series or any shares of any other class or series of
     Preferred Stock;
 
          (h) limitations, if any, on the issuance of additional shares of such
     class or series or any shares of any other class or series of Preferred
     Stock; and
 
          (i) such other preferences, powers, qualifications, special or
     relative rights and privileges thereof as the board of directors of the
     corporation, acting in accordance with this Restated Certificate of
     Incorporation, may deem advisable and are not inconsistent with law and the
     provisions of this Restated Certificate of Incorporation.
 
                                   ARTICLE V
 
     The Corporation reserves the right to amend, alter, change, or repeal any
provision contained in this Certificate of Incorporation, in the manner now or
hereafter prescribed by statute, and all rights conferred upon the stockholders
herein are granted subject to this right.
 
                                   ARTICLE VI
 
     The Corporation is to have perpetual existence.
 
                                  ARTICLE VII
 
     1. Limitation of Liability.  To the fullest extent permitted by the General
Corporation Law of the State of Delaware as the same exists or as may hereafter
be amended, a director of the Corporation shall not be personally liable to the
Corporation or its stockholders for monetary damages for breach of fiduciary
duty as a director.
 
     2. Indemnification.  The Corporation may indemnify to the fullest extent
permitted by law any person made or threatened to be made a party to an action
or proceeding, whether criminal, civil, administrative or investigative, by
reason of the fact that such person or his or her testator or intestate is or
was a director, officer or employee of the Corporation, or any predecessor of
the Corporation, or serves or served at any other enterprise as a director,
officer or employee at the request of the Corporation or any predecessor to the
Corporation.
 
     3. Amendments.  Neither any amendment nor repeal of this Article VII, nor
the adoption of any provision of the Corporation's Certificate of Incorporation
inconsistent with this Article VII, shall eliminate or reduce the effect of this
Article VII, in respect of any matter occurring, or any action or proceeding
accruing or arising or that, but for this Article VII, would accrue or arise,
prior to such amendment, repeal, or adoption of an inconsistent provision.
 
                                  ARTICLE VIII
 
     In the event any shares of Preferred Stock shall be redeemed or converted
pursuant to the terms hereof, the shares so converted or redeemed shall not
revert to the status of authorized but unissued shares, but instead shall be
canceled and shall not be re-issuable by the Corporation.
 
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                                   ARTICLE IX
 
     Holders of stock of any class or series of this corporation shall not be
entitled to cumulate their votes for the election of directors or any other
matter submitted to a vote of the stockholders, unless such cumulative voting is
required pursuant to Sections 2115 and/or 301.5 of the California Corporations
Code, in which event each such holder shall be entitled to as many votes as
shall equal the number of votes which (except for this provision as to
cumulative voting) such holder would be entitled to cast for the election of
directors with respect to his shares of stock multiplied by the number of
directors to be elected by him, and the holder may cast all of such votes for a
single director or may distribute them among the number of directors to be voted
for, or for any two or more of them as such holder may see fit, so long as the
name of the candidate for director shall have been placed in nomination prior to
the voting and the stockholder, or any other holder of the same class or series
of stock, has given notice at the meeting prior to the voting of the intention
to cumulate votes.
 
                                   ARTICLE X
 
     1. Number of Directors.  The number of directors which constitutes the
whole Board of Directors of the corporation shall be designated in the Bylaws of
the corporation.
 
     2. Election of Directors.  Elections of directors need not be by written
ballot unless the Bylaws of the corporation shall so provide.
 
                                   ARTICLE XI
 
     In furtherance and not in limitation of the powers conferred by statute,
the Board of Directors is expressly authorized to make, alter, amend or repeal
the Bylaws of the corporation.
 
                                  ARTICLE XII
 
     No action shall be taken by the stockholders of the corporation except at
an annual or special meeting of the stockholders called in accordance with the
Bylaws of the corporation, and no action shall be taken by the stockholders by
written consent.
 
                                  ARTICLE XIII
 
     Meetings of stockholders may be held within or without the State of
Delaware, as the Bylaws may provide. The books of the Corporation may be kept
(subject to any provision contained in the statutes) outside of the State of
Delaware at such place or places as may be designated from time to time by the
Board of Directors or in the Bylaws of the Corporation.
 
                                  ARTICLE XIV
 
     The name and mailing address of the incorporator are:
 
               Marnia Nichols, Esq.
               Wilson, Sonsini, Goodrich & Rosati
               650 Page Mill Road
               Palo Alto, California 94304-1050
 
     The undersigned incorporator hereby acknowledges that the above Certificate
of Incorporation of VIVUS, Inc. is her act and deed and that the facts stated
therein are true.
 
Dated: May 16, 1996
 
                                      /s/ MARNIA NICHOLS
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                                          Marnia Nichols
 
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