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                                                                   EXHIBIT 10.20


$ 30,000,000.00                                           New York, New York
                                                          December 19, 2002


1. OBLIGATION TO PAY

         FOR VALUE RECEIVED, the undersigned Borrower promises to pay to the
order of MICHAEL JAHARIS, an individual residing in New York, New York (the
"Lender"), the principal sum of Thirty Million Dollars ($30,000,000.00), on June
30, 2008, or such amount thereof as shall be outstanding hereunder on such date,
plus interest payable at the rate and in the manner provided in paragraph 3 of
this Additional Standby Facility Note, plus any costs and expenses incurred in
the enforcement of this Additional Standby Facility Note as provided in
paragraph 7 of this Additional Standby Facility Note. This Additional Standby
Facility Note is transferable by the holder hereof.

This Additional Standby Facility Note is issued pursuant to the Additional
Standby Facility Loan Agreement (as hereinafter defined), reference to which is
hereby made for other terms applicable to this Additional Standby Facility Note.

2. DEFINITIONS

         Except as otherwise defined herein, all capitalized terms used herein
which are defined in the Additional Standby Facility Loan Agreement shall have
the meaning ascribed to them therein. In addition, the following terms as used
herein shall be defined as follows:

                  (A) "Common Stock" shall mean the capital common stock of the
Borrower, consisting of 50,000,000 authorized shares $.01 par value.

                  (B) "Event of Default" shall mean any of the events set forth
in Paragraph 7 hereof.

                  (C) "First Advance Date" shall mean the date of the first
advance under this Additional Standby Facility Note and the Additional Standby
Facility Loan Agreement.

                  (D) "Interest Adjustment Date" shall mean the first day of
each month during the term of this Additional Standby Facility Note.

                  (E) "Additional Standby Facility Loan Agreement" shall mean a
Revolving Credit and Loan Agreement of even date herewith between Borrower and
the Lender pursuant to which this Additional Standby Facility Note is issued, as
the same may be amended and supplemented from time to time.




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                  (F) "Additional Standby Facility Loan Documents" shall mean
this Additional Standby Facility Note, the Additional Standby Facility Loan
Agreement, the Third Amended and Restated Registration Rights Agreement, the
Second Amended and Restated Security Agreement, the Second Amended and Restated
Patent Security Agreement, the Second Amended and Restated Stock Pledge
Agreement, the ATI Second Amended and Restated Subsidiary Guaranty, the ATI
Second Amended and Restated Subsidiary Security Agreement, the ATI Amended and
Restated Subsidiary Stock Pledge Agreement, the IEP Amended and Restated
Subsidiary Guaranty, the IEP Amended and Restated Subsidiary Security Agreement,
the UCC-1 financing statements executed in connection with the security
agreements, the Warrant, and each and every other document executed or delivered
in connection with the closing of this transaction, each such document being
referred to individually as a "Additional Standby Facility Loan Documents".

                  (G) "Prime Rate" shall mean the prime rate (or substantially
equivalent index, if such bank discontinues its prime rate) of SunTrust Bank
Miami, N.A., as announced from time to time, or, if such bank shall cease to
exist without any successor-in-interest, then the prime rate (or substantially
equivalent index, if no prime rate exists at such bank at such time) of any
national or regional bank selected by Lender having a comparable or larger asset
size.

                  (H) "Warrant" shall mean that certain Non-Detachable Common
Stock Purchase Warrant to purchase one million shares of Common Stock, as more
particularly described in the Additional Standby Facility Loan Agreement.

3. INTEREST

         The outstanding principal balance of this Additional Standby Facility
Note shall bear interest from the date hereof until the earlier of maturity,
imposition of the Default Rate (as hereinafter defined) or payment in full, at a
rate per annum equal to the Prime Rate in effect on each Interest Adjustment
Date (calculated on the basis of a 360-day year for the actual number of days
elapsed), on which date the interest rate shall be increased or decreased to the
extent of any increase or decrease in the Prime Rate from the Prime Rate in
effect on the immediately preceding Interest Adjustment Date. After maturity, or
upon the occurrence of and during the continuance of an Event of Default, if
earlier, the interest rate hereunder shall be increased to a rate equal to six
(6.0) percentage points in excess of the rate which would otherwise be in effect
hereunder.

         Notwithstanding any provision of this Additional Standby Facility Note
to the contrary, in the event that at any time the applicable rate of interest
payable by Borrower to Lender as stated in this Additional Standby Facility Note
(the "Contract Rate") exceeds the highest or maximum rate of interest
permissible to be charged by Lender under the laws of the State of New York or
under federal law, or is determined by a tribunal or court of competent
jurisdiction to be excessive and unenforceable (in each case, the "Maximum Legal
Rate"), then the interest rate payable under this Additional Standby Facility



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Note shall automatically be reduced to the Maximum Legal Rate for such period as
the Maximum Legal Rate is higher than the Contract Rate. If subsequently the
Contract Rate becomes less than the Maximum Legal Rate, then the interest rate
payable under this Additional Standby Facility Note shall automatically be
decreased to the Contract Rate. Any amounts paid in excess of the Maximum Legal
Rate shall be considered to have been payments in reduction of principal, and
the outstanding principal balance shall be adjusted to reflect such prepayments
of principal.

4. PAYMENTS

         Accrued interest shall be due and payable monthly on the seventh day of
each month. Interest may, at the option of the holder hereof, be deducted from
the amount of the proceeds of any disbursements hereunder.

         Upon maturity, the outstanding principal balance of this Additional
Standby Facility Note, together with unpaid interest accrued thereon and any
other sums payable hereunder, shall be payable in full.

         All sums received hereunder shall be applied first to the payment of
late charges, costs and expenses payable to Lender hereunder, then to interest
(in the order in which earliest earned) and the balance to principal. Borrower
shall have the right to prepay this Additional Standby Facility Note in full or
in part at any time without penalty.

         All payments shall be made in accordance with the terms of the
Additional Standby Facility Loan Agreement and shall be delivered to Lender at
its address at Michael Jaharis, c/o Steven K. Aronoff, P.C., 475 Park Avenue
South, 23rd Floor, New York, New York 10016 or at such other address as shall be
designated by Lender in a written notice to the Borrower.

         This Additional Standby Facility Note may also be prepaid in part or in
full by the holder of this Additional Standby Facility Note exercising the
Warrant in accordance with the terms of the Warrant. No partial prepayment of
this Additional Standby Facility Note by exercise of the Warrant shall abate
Borrower's obligation to make monthly interest payments on the reduced principle
balance, nor shall any such partial prepayment extend the maturity date of this
Additional Standby Facility Note.

5. ADVANCES

         Advances shall be made hereunder from time to time in accordance with
the terms of the Additional Standby Facility Loan Agreement, reference to which
is hereby made for the provisions regarding advances. At no time shall the
aggregate of all advances outstanding from time to time exceed $30,000,000.00.



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6. LATE CHARGE

         If any monthly payment of interest is not received by the Lender or any
holder hereof within 15 days after its due date, there shall be imposed on the
Borrower a late charge equal to five (5.0%) percent of such overdue payment.

7. ENFORCEMENT

         Upon the occurrence of an Event of Default (as hereinafter defined),
the entire principal balance remaining unpaid plus accrued interest shall, at
the option of the holder hereof, become immediately due and payable, and the
Borrower shall have all of the rights and remedies provided in the Additional
Standby Facility Loan Agreement and shall be entitled to be reimbursed for its
costs and expenses as set forth therein.

         An Event of Default is defined as any one of the following: (i) default
in the payment of any principal, interest or other amounts within ten (10) days
after such payment is due hereunder; (ii) breach of any provisions of this
Additional Standby Facility Note; or (iii) the occurrence of any Event of
Default under the Additional Standby Facility Loan Agreement.

         No extension of time for payment, or delay in enforcement hereof, nor
any renewal of this Additional Standby Facility Note with or without notice,
shall release the obligation of the Borrower to the Lender or holder hereof or
shall operate as a waiver of any of its rights.

         Presentment, demand, protest and notice of dishonor are hereby waived
by the Borrower.

8. RIGHT OF SETOFF

         Upon the occurrence of and during the continuance of any Event of
Default hereunder, the Lender is hereby authorized at any time and from time to
time, without notice to the Borrower (any such notice being expressly waived by
the Borrower) to set-off and apply any and all indebtedness at any time owing by
the Lender to or for the credit or the account of the Borrower against any and
all of the obligations of the Borrower now or hereafter existing under this
Additional Standby Facility Note or the Additional Standby Facility Loan
Agreement, irrespective of whether or not the Lender shall have made any demand
under this Additional Standby Facility Note or the Additional Standby Facility
Loan Agreement. The Lender agrees promptly to notify the Borrower after any such
setoff and application made by the Lender, provided that the failure to give
such notice shall not affect the validity of such setoff and application. The
rights of the Lender under this provision are in addition to other rights and
remedies (including, without limitation, any common law right of setoff) which
the Lender may have.




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9. WAIVER OF RIGHTS

         BORROWER ACKNOWLEDGES THAT THE TRANSACTION OF WHICH THIS ADDITIONAL
STANDBY FACILITY NOTE IS A PART IS A COMMERCIAL TRANSACTION. BORROWER HEREBY
WAIVES, TO THE EXTENT PERMITTED BY LAW, THE BENEFITS OF ALL VALUATION,
APPRAISEMENT, HOMESTEAD, EXEMPTION, STAY, REDEMPTION AND MORATORIUM LAWS, NOW IN
FORCE OR WHICH MAY HEREAFTER BECOME LAW.


10. SUBMISSION TO JURISDICTION; WAIVER OF BOND

         THE BORROWER HEREBY CONSENTS TO THE JURISDICTION OF ANY LOCAL, STATE,
OR FEDERAL COURT LOCATED WITHIN THE STATE OF NEW YORK AND WAIVES ANY OBJECTION
WHICH BORROWER MAY HAVE, BASED ON IMPROPER VENUE OR FORUM NON CONVENIENS, TO THE
CONDUCT OF ANY PROCEEDING IN ANY SUCH COURT AND WAIVES PERSONAL SERVICE OF ANY
AND ALL PROCESS UPON BORROWER, AND CONSENTS THAT ALL SUCH SERVICE OF PROCESS BE
MADE BY MAIL OR MESSENGER DIRECTED TO BORROWER AT THE ADDRESS SET FORTH BELOW
AND THAT SERVICE SO MADE SHALL BE DEEMED TO BE COMPLETED UPON THE EARLIER OF
ACTUAL RECEIPT OR THREE (3) DAYS AFTER THE SAME SHALL HAVE BEEN POSTED TO
BORROWER'S ADDRESS. THE BORROWER WAIVES ANY BOND OR SURETY OR SECURITY UPON SUCH
BOND WHICH MIGHT, BUT FOR THIS WAIVER, BE REQUIRED OF THE LENDER. NOTHING
CONTAINED IN THIS PARAGRAPH AFFECTS THE RIGHT OF THE LENDER TO SERVE LEGAL
PROCESS IN ANY OTHER MANNER PERMITTED BY LAW OR AFFECTS THE RIGHT OF THE LENDER
TO BRING ANY ACTION OR PROCEEDING AGAINST BORROWER OR BORROWER'S PROPERTY IN THE
COURTS OF ANY OTHER JURISDICTION.

11. WAIVER OF JURY TRIAL

         THE BORROWER WAIVES, TO THE EXTENT PERMITTED BY LAW, ANY RIGHT TO TRIAL
BY JURY WHICH BORROWER MAY HAVE IN ANY PROCEEDING BETWEEN LENDER AND BORROWER.

12. WAIVER OF PLAINTIFF'S RIGHTS

         THE BORROWER HEREBY AGREES NOT TO COMMENCE ANY LEGAL PROCEEDING AGAINST
THE LENDER IN THE JURISDICTION OF ANY LOCAL, STATE, OR FEDERAL COURT LOCATED



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WITHIN THE STATE OF FLORIDA UNLESS THE LENDER EXPRESSLY CONSENTS THERETO IN
WRITING.

13. GOVERNING LAW

         This Additional Standby Facility Note and its interpretation,
construction, validity and enforceability shall be governed by the laws of the
State of New York.


                                             KOS PHARMACEUTICALS, INC.


                                             By:
                                                --------------------------------
                                                 Name:  Adrian Adams
                                                 Title: President



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STATE OF NEW YORK      )
                       )  ss.:
COUNTY OF              )

         On the ______ day of December ___, 2002, before me came Adrian Adams,
to me known, who, being by me duly sworn, did depose and say that he resides at
No.________________ _______________________________________________; that he is
the President of Kos Pharmaceuticals, Inc., the corporation described in and
which executed, the foregoing instrument; that the foregoing instrument was
executed without corporate seal by order of the Board of Directors of said
corporation; that he signed his name thereto by like order.




                                                --------------------------------
                                                Notary Public
                                                My commission expires:





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