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                                                                    EXHIBIT 10.5

                   FOURTH AMENDMENT TO CONVERTIBLE BRIDGE LOAN
                              AND WARRANT AGREEMENT

      THIS FOURTH AMENDMENT TO CONVERTIBLE BRIDGE LOAN AND WARRANT AGREEMENT
(this "Amendment") is made as of October 7, 2003, by and between Akorn, Inc. a
Louisiana corporation (the "Company"), and The John N. Kapoor Trust dated
9/20/89 (the "Lender").

      WHEREAS, the Company and the Lender are parties to that certain
Convertible Bridge Loan and Warrant Agreement dated as of July 12, 2001 (as
amended from time to time, the "Agreement"); and

      WHEREAS, the Company and the Lender wish to further amend the Agreement
pursuant to the terms set forth herein.

      NOW, THEREFORE, for and in consideration of the premises and mutual
agreements herein contained and for the purposes of setting forth the terms and
conditions of this Amendment, the parties, intending to be bound, hereby agree
as follows:

      1. Incorporation of the Agreement. All capitalized terms which are not
defined hereunder shall have the same meanings as set forth in the Agreement. To
the extent any terms and provisions of the Agreement are inconsistent with the
amendments set forth in Paragraph 2 below, such terms and provisions shall be
deemed superseded hereby. Except as specifically set forth herein, the Agreement
shall remain in full force and effect and its provisions shall be binding on the
parties hereto.

      2. Amendments to the Agreement.

            2.1 Definitions. The definition of "Senior Loan Agreement" is hereby
amended and restated in its entirety to read as follows:

                  "Senior Loan Agreement" shall mean that certain Credit
            Agreement dated as of October 7, 2003, among Akorn, Inc., Akorn (New
            Jersey), Inc., LaSalle Bank National Association and certain other
            parties thereto.

            2.2 Section 9.

                  (a) Section 9(c) of the Agreement is hereby amended and
      restated in its entirety to read as follows:

                        "(c) (i) any default or breach by the Company of or
                  under any agreement between the Company and NeoPharm, Inc. for
                  borrowed money, (ii) a material breach under any real property
                  lease agreements or capital equipment lease agreements, by
                  which the Company is bound or obligated, or (iii) any default
                  under the Senior Loan Agreement pursuant to which the lenders
                  parties thereto accelerate the maturity of the indebtedness
                  thereunder;"
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                  (b) Section 9(d) of the Agreement is hereby amended and
      restated in its entirety to read as follows:

                        "(d) [INTENTIONALLY OMITTED];"

                  (c) Section 9(e) of the Agreement is hereby amended and
      restated in its entirety to read as follows:

                        "(e) The Company shall have (i) failed to obtain all
                  necessary shareholder consents to the Tranche A Loan, Tranche
                  B Loan, the issuance of the Tranche A Note and the issuance of
                  the Tranche B Note on or prior to September 30, 2004, or (ii)
                  on or prior to September 30, 2004, provided the Lender with an
                  opinion of counsel reasonably acceptable to the Lender stating
                  that no such shareholder consents are currently required."

            2.3 Section 10. Section 10.14 of the Agreement is hereby amended and
restated in its entirety to read as follows:

                  "10.14 Subordination. The indebtedness evidenced by the Notes
            shall be subordinated to certain indebtedness of the Company
            pursuant to that certain Subordination and Intercreditor Agreement
            dated as of October 7, 2003 (the "Subordination Agreement"),
            executed by the Lender in favor of LaSalle Bank National Association
            and acknowledged by the Company and Akorn (New Jersey), Inc."

      3. Effectuation. The amendment to the Agreement contemplated by this
Amendment shall be deemed effective immediately upon the full execution of this
Amendment and without any further action required by the parties hereto. There
are no conditions precedent or subsequent to the effectiveness of this
Amendment.

      4. Fees and Expenses. The Company agrees to pay on demand all costs and
expenses of or incurred by the Lender (including, but not limited to, reasonable
legal fees and expenses) in connection with the evaluation, negotiation,
preparation, execution and delivery of this Amendment, to the extent permitted
by that certain Reaffirmation of Subordination and Intercreditor Agreement dated
the date hereof from the Lender in favor of NeoPharm, Inc.

      5. Counterparts. This Amendment may be executed in two or more
counterparts, each of which shall be deemed an original, and all of which
together shall constitute one and the same instrument. One or more counterparts
of this Amendment may be delivered by facsimile, with the intention that
delivery by such means shall have the same effect as delivery of an original
counterpart thereof.

                            [SIGNATURE PAGE FOLLOWS]

                                    * * * * *


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      IN WITNESS WHEREOF, the parties have executed this Fourth Amendment to
Convertible Bridge Loan and Warrant Agreement as of the date first written
above.

AKORN, INC.


By:
   ---------------------------
Name:
     -------------------------
Title:
      ------------------------

THE JOHN N. KAPOOR TRUST DATED
9/20/89

By:
   ---------------------------
   John N. Kapoor, Trustee