<PAGE>
                                                                    EXHIBIT 10.9

                              HALSEY DRUG CO., INC.

                                  AMENDMENT TO
                    DEBENTURE AND WARRANT PURCHASE AGREEMENT

                          DATED AS OF DECEMBER 20, 2002

         This Amendment to the Debenture and Warrant Purchase Agreement is made
as of this 20th day of December, 2002, by and among Halsey Drug Co., Inc., a New
York corporation (the "Company"), and each of the Purchasers set forth on the
signature page hereto (the "Purchasers").

                                R E C I T A L S :

         WHEREAS, pursuant to that certain Debenture and Warrant Purchase
Agreement dated as of May 26, 1999 (the "Purchase Agreement") executed by the
Company in favor of the Purchasers, the Company issued its 5% Convertible Senior
Secured Debentures due March 15, 2003 (the "Existing Debentures"); and

         WHEREAS, pursuant to a certain Debenture Purchase Agreement dated on or
about December 20, 2002 (the "2002 Purchase Agreement"), proposed to be executed
by the Company in favor of Care Capital LLC, Essex Woodlands Health Ventures and
the other purchasers listed on the signature page thereto, the Company proposes
to issue its 5% Convertible Senior Secured Debentures due March 31, 2006 (the
"New Debentures"); and

         WHEREAS, as a condition to the investment in the New Debentures to be
made by the Purchasers listed in the 2002 Purchase Agreement (the "New
Holders"), the New Holders have required that the Purchase Agreement be amended
to (i) extend the maturity date of the Existing Debentures from March 15, 2003
to March 31, 2006, and (ii) provide that the holders of the Existing Debentures
have veto rights for certain material Company transactions; and

         WHEREAS, as an inducement for the New Holders to make the investment
pursuant to the 2002 Purchase Agreement, the Company and the Purchasers desire
to amend the Purchase Agreement as hereinafter provided;

         NOW, THEREFORE, in consideration of the foregoing recitals and the
covenants herein contained, the parties hereto agree as follows:

         1.       Capitalized terms used herein and not otherwise defined shall
have the meanings provided in the Purchase Agreement.

         2.       Section 1.1 of the Purchase Agreement is hereby amended to
delete Subsection (a) of such Section and replace same with the following:

                  "(a) its 5% Convertible Senior Secured Debentures due March
                  31, 2006 in the aggregate principal amount of $22,862,603.04
                  (the "Debentures"),"

         3.       The Purchase Agreement is hereby amended to provide that the
maturity date of the Debentures shall be March 31, 2006 and that any reference
to a maturity date of March 15, 2003 shall be deemed changed to March 31, 2006.
<PAGE>
         4.       The definition of Debentures as contained in Section 1.1 of
the Purchase Agreement is hereby revised to include all 5% Convertible Senior
Secured Debentures having an original maturity date of March 15, 2003 issued
pursuant to the Purchase Agreement, including, without limitation, all 5%
Convertible Senior Secured Debentures issued by the Company to the Purchasers in
satisfaction of interest payments due and payable thereunder. Exhibit A-1 to
this Amendment to the Debenture and Warrant Purchase Agreement sets forth all
Debentures and Warrants issued to the Purchasers pursuant to the Purchase
Agreement through the date hereof.

         5.       Each Purchaser agrees to surrender to the Company each
Debenture instrument issued to such Purchaser as described in Exhibit A-1 to
this Amendment to Debenture and Warrant Purchase Agreement against the issuance
by the Company of an Amended and Restated 5% Convertible Senior Secured
Debenture of like principal amount due March 31, 2006 in substantially the form
attached as Exhibit B to this Amendment to the Debenture and Warrant Purchase
Agreement.

         6.       A new Section 9.16 is hereby added to the Purchase Agreement
                  as follows:

                  "9.16 Debentureholders Agreement. Each of the Company and the
                  holders of the Debentures has concurrently executed the form
                  of Debentureholders Agreement attached as Exhibit O hereto."

         7.       Section 12.1(c) of the Purchase Agreement is hereby deleted in
                  its entirety and the following inserted in lieu thereof:

                  "If the Company shall default in the performance of any other
                  material agreement or covenant contained in this Agreement or
                  in any other agreement executed in connection with this
                  Agreement, including that certain Registration Rights
                  Agreement dated December 20, 2002 among the Company, the
                  Purchasers and the other parties thereto, and such default
                  shall not have been remedied to the satisfaction of the Holder
                  or Holders of at least a majority in aggregate principal
                  amount of the Debentures then outstanding, within thirty-five
                  (35) days after a Default Notice shall have been given to the
                  Company (the Company to give forwith to all other Holders of
                  Debentures at the time outstanding written notice of the
                  receipt of such Default Notice, specifying the default
                  referred to therein);"

         8.       Subparagraph (a) of Article XIII is hereby amended to add the
                  following at the end of such Subparagraph:

                  "Notwithstanding the foregoing or anything to the contrary
                  contained in this Article XIII, no amendment to Section 9.16
                  shall be valid unless the same shall be in writing and signed
                  by the Company and the holders of at least 66 2/3% in the
                  aggregate principal amount of the Debentures (including for
                  purposes of such calculation the principal amount of those
                  Debentures that at such time have been converted into shares).

         9.       Except as amended above, the terms of the Purchase Agreement
shall remain in full force and effect.

         10.      This Amendment to Debenture and Warrant Purchase Agreement and
the rights of the parties hereunder shall be governed in all respects by laws in
the State of New York wherein the terms of this Amendment were negotiated.

         11.      This Amendment to Debenture and Warrant Purchase Agreement may
be executed in any number of counterparts, each of which shall be original, but
all of which together shall constitute one instrument.

                           [SIGNATURE PAGES TO FOLLOW]

                                       2
<PAGE>
         IN WITNESS WHEREOF, the Company and the Purchasers have caused this
Amendment to be duly executed all on the day and year first above written.

HALSEY DRUG CO., INC.

By:___________________________________
   Name:  Michael Reicher
   Title: Chief Executive Officer

PURCHASERS

<TABLE>
<S>                                     <C>
ORACLE STRATEGIC PARTNERS, L.P.         GALEN PARTNERS III, L.P.
By: Oracle Strategic Capital L.L.C.,    By: Claudius, L.L.C., General Partner
General Partner                         610 Fifth Avenue, 5th Fl.
200 Greenwich Avenue                    New York, New York 10019
3rd Floor
Greenwich, CT 06830

___________________________________     ________________________________________
By:  Joel Liffmann                      By:  Srini Conjeevaram
Its: Authorized Agent                   Its: General Partner

GALEN EMPLOYEE FUND III, L.P.           GALEN PARTNERS INTERNATIONAL, III, L.P.
By: Wesson Enterprises, Inc.            By: Claudius, L.L.C., General Partner
610 Fifth Avenue, 5th Floor             610 Fifth Avenue, 5th Floor
New York, New York 10020                New York, New York 10020

___________________________________     ________________________________________
By:  Bruce F. Wesson                    By:  Srini Conjeevaram
Its: General Partner                    Its: General Partner

ALAN SMITH                              PATRICK COYNE
21 Bedlow Avenue                        800 Merion Square Road
Newport, Rhode Island 02840             Gladwyne, PA 19035

___________________________________     ________________________________________

MICHAEL WEISBROT                        SUSAN WEISBROT
1136 Rock Creek Road                    1136 Rock Creek Road
Gladwyne, Pennsylvania 19035            Gladwyne, Pennsylvania 19035

___________________________________     ________________________________________
</TABLE>

                                       3
<PAGE>
<TABLE>
<S>                                     <C>
GREG WOOD                               DENNIS ADAMS
c/o D.R. International                  120 Kynlyn Road
7474 No. Figueroa Street                Radnor, Pennsylvania 19312
Los Angeles, California 90041

___________________________________     ________________________________________

BERNARD SELZ
c/o Furman Selz
230 Park Avenue
New York, New York 10069

___________________________________
</TABLE>

                                       4
<PAGE>
                                   EXHIBIT A-1

                            LIST OF DEBENTUREHOLDERS

                                       5
<PAGE>
                                    EXHIBIT B

                          FORM OF AMENDED AND RESTATED
                     5% CONVERTIBLE SENIOR SECURED DEBENTURE

                                       6
<PAGE>
                                    EXHIBIT O

                            DEBENTUREHOLDER AGREEMENT

                                       7