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Prospectus Supplement No. 4                    Filed Pursuant to Rule 424(b)(3)
(To Prospectus dated September 25, 1998)                 SEC File No. 333-57501


                                  $111,095,000

                                  ALPHARMA INC.
                 5 3/4% CONVERTIBLE SUBORDINATED NOTES DUE 2005

     All capitalized terms used but not defined herein shall have the meanings
ascribed to them in the Prospectus, dated September 25, 1998, as supplemented by
Prospectus Supplement No. 1, Prospectus Supplement No. 2 and Prospectus
Supplement No. 3 (the "Prospectus"), forming a part of the Registration
Statement on Form S-3 (Registration No. 333-57501). Any cross references in this
Prospectus Supplement No. 4 refer to portions of the Prospectus.

     The purpose of this Prospectus Supplement No. 4 is to amend and supplement
the information set forth in the Prospectus regarding the Selling
Securityholders. The following table sets forth the names of additional Selling
Securityholders and (i) the amount of Notes owned by each Selling Securityholder
listed below as of October 4, 1999; (ii) the maximum amount of Notes which may
be offered by each Selling Securityholder listed below under this Prospectus;
(iii) the number of shares of Common Stock owned by each Selling Securityholder
listed below as of October 4, 1999; and (iv) the maximum number of shares of
Common Stock which may be offered by each Selling Securityholder listed below
under this Prospectus. Each of the Selling Securityholders named below acquired
Notes in the amounts reflected in the table below from a Selling Securityholder
named in the Prospectus. All information with respect to beneficial ownership
has been furnished to the Company by the respective Selling Securityholders.
Beneficial ownership of the Notes and Common Stock listed in the table has been
determined in accordance with the applicable rules and regulations promulgated
under the Exchange Act.



                                           AGGREGATE                   PRINCIPAL        NO. OF      NO. OF SHARES
                                           PRINCIPAL       % OF     AMOUNT OF NOTES     SHARES     OFFERED-HEREBY
  NAME OF SELLING SECURITY HOLDER       AMOUNT OF NOTES    CLASS     OFFERED HEREBY     (1)(2)         (1)(2)
- --------------------------------------  ---------------    -----    ---------------     -------    --------------
                                                                                      
Deephaven Domestic Convertible Trading    $  4,500,000      3.60%     $ 4,500,000       157,377       157,377
Ltd.
Total                                     $  4,500,000      3.60%     $ 4,500,000       157,377       157,377
                                          ============      =====     ===========       =======       =======


- ------------------

(1)  All share amounts set forth represent less than 1% of the outstanding Class
     A Common Stock.

(2)  Reflects the shares of Common Stock into which the Notes held by such
     Selling Securityholder are convertible at the initial conversion rate. The
     Conversion Price and the number of shares of Common Stock issuable upon
     conversion of the Notes are subject to adjustment under certain
     circumstances. Assumes conversion into Class A Common Stock of the full
     amount of Notes held by the Selling Securityholder at the initial
     conversion rate and the offering of such shares by such Selling
     Securityholder pursuant to this Prospectus. See "Description of
     Notes--Conversion Rights."

     Because the Selling Securityholders may, pursuant to this Prospectus, offer
all or some portion of the Notes they presently hold or, with respect to the
Common Stock, have the right to acquire upon conversion of such Notes, no
estimate can be given as to the amount of the Notes and Common Stock that will
be held by the Selling Securityholders upon termination of any such sales. In
addition, the Selling Securityholders identified above and in the Prospectus may
have sold, transferred or otherwise disposed of all or a portion of their Notes
and Common Stock since the date on which they provided the information regarding
their Notes and Common Stock, in transactions exempt from the registration
requirements of the Securities Act. See "Plan of Distribution." Such sales would
affect the data in the table above.

     The Company may from time to time, in accordance with the Registration
Rights Agreement, supplement or amend the Prospectus to reflect the required
information concerning any transferee, pledgee, donee or successor to the
Selling Securityholders named in the Prospectus.

     The date of this Prospectus Supplement is October 4, 1999.