<PAGE>   1
           As filed with the Securities and Exchange Commission on June 24, 1996
                                                       Registration No. 33-75698

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                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                        POST-EFFECTIVE AMENDMENT NO. 1 TO

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      Under
                           THE SECURITIES ACT OF 1933

                                   VIVUS, INC.
             (Exact name of regist ant as specified in its charter)

          Delaware                                       94-3136179
(State or other jurisdiction of 
incorporation or organization)              (I.R.S. Employer Identification No.)

                         545 Middlefield Road, Suite 200
                          Menlo Park, California 94025
                    (Address of principal executive offices)

                            1991 INCENTIVE STOCK PLAN

                            1994 DIRECTOR OPTION PLAN

                        1994 EMPLOYEE STOCK PURCHASE PLAN

                            (Full title of the Plans)

                                  DAVID YNTEMA
                             Chief Financial Officer
                         545 Middlefield Road, Suite 200
                          Menlo Park, California 94025
                                 (415) 325-5511

            (Name, address and telephone number of agent for service)

                                   Copies to:

                            ROBERT D. BROWNELL, ESQ.
                        Wilson, Sonsini Goodrich & Rosati
                            Professional Corporation
                               650 Page Mill Road
                        Palo Alto, California 94304-1050
                                 (415) 493-9300

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<PAGE>   2
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                         CALCULATION OF REGISTRATION FEE
================================================================================

<TABLE>
<CAPTION>
                                            Proposed     Proposed
               Title of                     Maximum      Maximum
              Securities      Amount        Offering    Aggregate    Amount of
                to be         to be          Price       Offering  Registration
              Registered    Registered     Per Share      Price         Fee
- --------------------------------------------------------------------------------
<S>                           <C>            <C>           <C>           <C>
See below*                    N/A*           N/A*          N/A*          N/A*
- --------------------------------------------------------------------------------
</TABLE>


*        No additional securities are to be registered, and registration fees
         were paid upon filing the original Registration Statement No. 33-75698.




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<PAGE>   3
                                   VIVUS, INC.
                        POST-EFFECTIVE AMENDMENT NO. 1 TO
                       REGISTRATION STATEMENT ON FORM S-8

                                EXPLANATORY NOTE

         This Post-Effective Amendment No. 1 (the "Amendment") to that certain
Registration Statement on Form S-8 (File No. 33-75698) (the "Registration
Statement") is being filed pursuant to Rule 414 under the Securities Act of
1933, as amended (the "Act") by Vivus, Inc., a Delaware corporation ("Vivus
Delaware" or the "Company"), which is the successor to Vivus, Inc., a California
corporation ("Vivus California"), following a statutory merger effective on May
24, 1996 (the "Merger") for the purpose of changing Vivus California's state of
incorporation. Prior to the Merger, Vivus Delaware had no assets or liabilities
other than nominal assets or liabilities. In connection with the Merger, Vivus
Delaware succeeded by operation of law to all of the assets and liabilities of
Vivus California. The Merger was approved by the shareholders of Vivus
California at a meeting for which proxies were solicited pursuant to Section
14(a) of the Securities Exchange Act of 1934, as amended (the "1934 Act").

         Except as modified by this Amendment, Vivus Delaware, by virtue of this
Amendment, expressly adopts the Registration Statement as its own registration
statement for all purposes of the Act and the 1934 Act.

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  INFORMATION INCORPORATED BY REFERENCE.

         The following documents and information previously filed with the
Securities and Exchange Commission are hereby incorporated by reference:

         (a) The Company's Annual Report on Form 10-K for the fiscal year ended
December 31, 1995, filed pursuant to Section 13 of the Securities Exchange Act
of 1934, as amended (the "Exchange Act");

         (b) The Form 10-Q of the Registrant for the quarter ended March 31,
1996 filed pursuant to Section 13(a) of the Exchange Act.

         (c) The description of the Common Stock of the Registrant that is
contained in the Registration Statement on Form 8-A filed pursuant to Section 12
of the Exchange Act effective April 6, 1994, including any amendment or report
filed for the purpose of updating such description.

         (d) All documents filed by the Registrant pursuant to Sections 13(a),
13(c), 14 and 15(d) of the Exchange Act subsequent to the filing of this
Registration Statement and prior to the filing of a post-effective amendment
which indicates that all securities offered have been sold or which deregisters
all securities then remaining unsold, shall be deemed to be incorporated by
reference in the Registration Statement and to be part hereof from the date of
filing of such documents.

Item 4.  DESCRIPTION OF SECURITIES.

         Not applicable.



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<PAGE>   4
Item 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.

         Not applicable.

Item 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

         The Company's Certificate of Incorporation limits the liability of
directors to the maximum extent permitted by Delaware law. Delaware law provides
that directors of a corporation will not be personally liable for monetary
damages for breach of their fiduciary duties as directors, except for liability
(i) for any breach of their duty of loyalty to the corporation or its
stockholders, (ii) for acts or omissions not in good faith or that involve
intentional misconduct or a knowing violation of law, (iii) for unlawful
payments of dividends or unlawful stock repurchases or redemptions as provided
in Section 174 of the Delaware General Corporation Law, or (iv) for any
transaction from which the director derived an improper personal benefit.

         The Company's Bylaws provide that the Company shall indemnify its
directors and officers and may indemnify its employees and other agents to the
fullest extent permitted by law. The Company believes that indemnification under
its Bylaws covers at least negligence and gross negligence on the part of
indemnified parties. The Company's Bylaws also permit the Company to secure
insurance on behalf of any officer, director, employee or other agent for any
liability arising out of his or her actions in such capacity, regardless of
whether the Company would have the power to indemnify him or her against such
liability under the General Corporation Law of Delaware. The Company currently
has secured such insurance on behalf of its officers and directors.

         The Company has entered into agreements to indemnify its directors and
officer, in addition to indemnification provided for in the Company's Bylaws.
Subject to certain conditions, these agreements, among other things, indemnify
the Company's directors and officers for certain expenses (including attorney's
fees), judgments, fines and settlement amounts incurred by any such person in
any action or proceeding, including any action by or in the right of the
Company, arising out of such person's services as a director or officer of the
Company, any subsidiary of the Company or any other company or enterprise to
which the person provides services at the request of the Company.

Item 7.  EXEMPTION FROM REGISTRATION CLAIMED.

         Not applicable.

Item 8.  EXHIBITS.

         Exhibit
         Number                     Document

         23.1              Consent of Independent Public Accountants
                           (See page 7). 

         24.1              Power of Attorney (See page 6).


                                       -2-



<PAGE>   5
Item 9.  UNDERTAKINGS.

         (a) The undersigned registrant hereby undertakes:

                  (1) To file, during any period in which offers or sales are
being made, a post-effective amendment to this registration statement:

                           (i) To include any prospectus required by Section
10(a)(3) of the Securities Act of 1933;

                           (ii) To reflect in the prospectus any facts or events
arising after the effective date of the registration statement (or the most
recent post-effective amendment thereof) which, individually or in the
aggregate, represent a fundamental change in the information set forth in the
registration statement;

                           (iii) To include any material information with
respect to the plan of distribution not previously disclosed in the registration
statement or any material change to such information in the registration
statement;

         Provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not
apply if the registration statement is on Form S-3, or Form S-8, and the
information required to be included in a post-effective amendment by those
paragraphs is contained in periodic reports filed by the registrant pursuant to
Section 13 or Section 15(d) of the Securities Exchange Act of 1934 that are
incorporated by reference in the registration statement.

                  (2) That for the purpose of determining any liability under
the Securities Act of 1933, each such post-effective amendment shall be deemed
to be a new registration statement relating to the securities offered therein,
and the offering of such securities at that time shall be deemed to be the
initial bona fide offering thereof.

                  (3) To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.

         (b) The undersigned registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act of 1933, each filing of the
registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Securities Exchange Act of 1934 that is incorporated by reference in the
registration statement shall be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.

         (c) The undersigned registrant hereby undertakes:

                  (1) To deliver or cause to be delivered with the prospectus to
each employee or director to whom the prospectus is sent or given a copy of the
registrant's annual report to shareholders for its last fiscal year, unless such
employee or director otherwise has received a copy of such report, in which case
the registrant shall state in the prospectus that it will furnish a copy of such
report on request of the employee or director. If the last fiscal year of the
registrant has ended within 120 days prior to the use of the prospectus, the
annual report of the registrant for the preceding fiscal year may be so
delivered, but within such 120-day period the annual report for the latest
fiscal year will be furnished to each such employee or director.

                  (2) To transmit or cause to be transmitted to all employees
and directors participating in the plans, who do not otherwise receive such
material as shareholders of the issuer, at the time and in the manner such
material is 



                                       -3-

<PAGE>   6
sent to its shareholders, copies of all reports, proxy statements
and other communications distributed to its shareholders generally.

                  (d) Insofar as indemnification for liabilities arising under
the Securities Act may be permitted to directors, officer and controlling
persons of the registrant pursuant to the Delaware General Corporation Law, the
Certificate of Incorporation and the Bylaws of the registrant, Indemnification
Agreements entered into between the registrant and its officers and directors,
or otherwise, the registrant has been advised that in the opinion of the
Securities and Exchange Commission such indemnification is against public policy
as expressed in the Securities Act and is, therefore, unenforceable. In the
event that a claim for indemnification against such liabilities (other than the
payment by the registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered hereunder, the registrant will,
unless in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the
Securities Act and will be governed by the final adjudication of such issue.



                                       -4-



<PAGE>   7



                                   SIGNATURES

                  Pursuant to the requirements of the Securities Act of 1933,
the Registrant certifies that it has reasonable grounds to believe that it meets
all of the requirements for filing on Form S-8 and has duly caused this
Post-Effective Amendment No. 1 to the Registration Statement to be signed on its
behalf by the undersigned, thereunto duly authorized in the City of Menlo Park,
State of California on June 24, 1996.

                               VIVUS, INC.

                               By:      /s/ David Yntema
                                        --------------------------------------
                                        David Yntema
                                        Chief Financial Officer

                               By:      /s/ Leland F. Wilson
                                        --------------------------------------
                                        Leland F. Wilson
                                        President and Chief Executive Officer



                                       -5-



<PAGE>   8



                                POWER OF ATTORNEY

         KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature
appears below constitutes and appoints Robert D. Brownell, David Yntema and
Leland F. Wilson, jointly and severally, his attorneys-in-fact, each with the
power of substitution, for him in any and all capacities, to sign any amendments
to this Post-Effective Amendment No. 1 to the Registration Statement, and to
file the same, with exhibits thereto and other documents in connection
therewith, with the Securities and Exchange Commission, hereby ratifying and
confirming all that each of said attorneys-in-fact, or his substitute or
substitutes, may do or cause to be done by virtue hereof.

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the date indicated.


<TABLE>
<CAPTION>
            SIGNATURE                            TITLE                                      DATE
            ---------                            -----                                      ----

<S>                                 <C>                                              <C> 
/s/ LELAND F. WILSON                President and Chief Executive                    June 24, 1996
- --------------------------          Officer (Principal Executive Officer)
Leland F. Wilson                    

/s/ VIRGIL A. PLACE, M.D.           Chairman of the Board of                         June 24, 1996
- --------------------------          Directors
Virgil A. Place, M.D.               

/s/ DAVID YNTEMA                    Chief Financial Officer                          June 24, 1996
- --------------------------          (Principal Financial Officer and
David Yntema                        Principal Accounting Officer)
                                    

                                    Director      
- --------------------------
Richard L. Casey

/s/ SAMUEL D. COLELLA               Director                                         June 24, 1996
- --------------------------
Samuel D. Colella

                                    Director      
- --------------------------
Brian H. Dovey

/s/ ELIZABETH A. FETTER             Director                                         June 24, 1996
- --------------------------
Elizabeth A. Fetter

                                    Director       
- --------------------------
Peter Barton Hutt
</TABLE>




                                       -6-



<PAGE>   9



                                                                    EXHIBIT 23.1

                   CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS





         As independent public accountants, we hereby consent to the
incorporation by reference in this Post-Effective Amendment No. 1 to the
Registration Statement (Form S-8 No. 33-75698) pertaining to the 1991 Incentive
Stock Plan, the 1994 Director Option Plan and the 1994 Employee Stock Purchase
Plan of Vivus, Inc. of our report dated January 25, 1996 included in or made
part of this Registration Statement for Vivus, Inc.




ARTHUR ANDERSEN, LLP
Oakland, California
June 24, 1996



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