Document:

EXHIBIT 10.18

                     AMENDED AND RESTATED SECURITY AGREEMENT

         This Amended and Restated Security Agreement dated as of December 21,
1999, by and between KOS PHARMACEUTICALS, INC., a Florida corporation having a
principal place of business at 1001 Brickell Bay Drive, 25th Floor, Miami, FL
33131 (hereinafter called the "Borrower") and MICHAEL JAHARIS, an individual
residing in South Norwalk, Connecticut(hereinafter called the "Lender").

                              W I T N E S S E T H:

         WHEREAS, the Lender has agreed to make a loan in the amount of
$50,000,000.00 (the "December Loan") as more fully described and set forth in a
loan agreement of even date herewith between the Lender and the Borrower (the
"December Loan Agreement"); and

         WHEREAS, the Lender previously entered into a Revolving Credit and Loan
Agreement dated as of September 1, 1999 with Borrower (the "September Loan
Agreement") whereby Lender agreed to extend a line of credit to Borrower in the
maximum principal amount of $50,000,000 (the "September Loan"); and

         WHEREAS, the Lender also previously entered into a Revolving Credit and
Loan Agreement dated as of July 1, 1998 with Borrower, as amended by amendment
of even date herewith (the "Unsecured Credit Agreement")(the December and
September Loan Agreements together with the Unsecured Credit Agreement shall
hereinafter be referred to as the "Loan Agreements") whereby Lender agreed to
extend an unsecured line of credit to Borrower in the maximum principal amount
of $30,000,000 (the "July Loan")(the December, September and July Loans shall
hereinafter be referred to collectively as the "Loans"), which amount is fully
advanced to Borrower as of the date hereof; and

         WHEREAS, the December and September Loan Agreements provide, in part,
that the Loans shall be secured by a blanket lien upon all personal property
owned by Borrower;

         WHEREAS, this Amended and Restated Security Agreement amends and
restates that Security Agreement dated September 1, 1999 by and between Borrower
and Lender (the "Original Security Agreement") granting a blanket lien security
interest to Lender to secure the September Loan;

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         NOW, THEREFORE, in consideration of the mutual promises and covenants
contained herein and in the Loan Agreements, and One ($1.00) Dollar, the receipt
and sufficiency of which is hereby acknowledged, the Lender and the Borrower
hereby agree as follows:

         1. GRANT OF SECURITY INTEREST. (a) The Borrower hereby grants to
Lender, and hereby confirms and ratifies its grant to Lender pursuant to the
Original Security Agreement as of September 1, 1999 of, a security interest (the
"Security Interest") in all accounts, accounts receivable and contract rights,
inventory, equipment and machinery, trademarks, trade names and service marks,
patents, licenses, chattel paper, instruments, documents, letters of credit and
general intangibles, and all proceeds of any of the foregoing, all as more
particularly described on Schedule A attached hereto and made a part hereof
(the"Collateral"), to secure the performance of the following obligations of the
Borrower (hereinafter collectively referred to as the "Indebtedness"):

                  (i) Borrower's liabilities and obligations under the Loan
         Documents as defined in paragraph 5(b) below;

                  (ii) Borrower's liabilities and obligations under the
         September Loan, the September Loan Agreement and any and all documents
         executed in connection therewith, as amended and/or restated
         (collectively, the "September Loan Documentation"); and

                  (iii) Borrower's liabilities and obligations under the July
         Loan, the Unsecured Credit Agreement and any and all documents executed
         in connection therewith, as amended and/or restated (collectively, the
         "July Loan Documentation"); and

                  (iv) Any other obligations of the Borrower in favor of Lender
         which may now exist or which may hereinafter arise pursuant to any
         future loan transaction between the Borrower and the Lender.

            (b) The Borrower is hereby deemed a "debtor" and the Lender is
hereby deemed a "secured party" as those terms are used in the Connecticut
Uniform Commercial Code.

         2. COVENANTS AND WARRANTIES OF THE BORROWER. The Borrower hereby
warrants and covenants:

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            (a) That except for the security interest granted hereby, and the
Security Interests shown on Schedule B attached hereto and made a part hereof,
the Borrower:

                  (i) is the owner of the Collateral, free and clear of any
         lien, security interest, encumbrance or claim of right,

                  (ii) shall defend the Collateral against any and all claims
         and demands of all persons at any time claiming the same or any
         interest therein, and

                  (iii) shall execute and deliver to the Lender such financing
         statements, or other documents as the Lender may at any time or from
         time to time reasonably require or which may be necessary or
         appropriate to establish and maintain a valid and enforceable security
         interest in the Collateral as security for the Indebtedness, subject to
         no prior security interests or encumbrances.

            (b) That the Collateral shall be kept only at the Borrower's
principal place of business at 1001 Brickell Bay Drive, 25th Floor, Miami, FL
33131 and at the locations, if any, set forth on Schedule C, attached hereto and
made a part hereof (collectively, the "Premises") except as required in the
ordinary course of business; that the Borrower will promptly notify the Lender
of any change in the location of the Collateral, and that the Borrower will not
remove the Collateral from the Premises, except as hereinbefore or hereafter
permitted, without the written consent of the Lender.

            (c) That the Borrower shall immediately notify the Lender in writing
of any change in or discontinuance of any of the Borrower's places of business
or other facilities listed in this Amended and Restated Security Agreement,
including any schedules attached hereto.

            (d) That the Borrower will not sell or offer to sell or otherwise
transfer the Collateral or any interest therein without written consent of the
Lender, except that the Borrower may, at the Borrower's own expense, in the
ordinary course of business, sell any of the inventory normally held by the
Borrower for such purpose, and use and consume, in the ordinary course of
business, any raw materials, supplies and materials normally held by the
Borrower for such purpose. Unless an Event of Default (as hereinafter defined)
has occurred and is continuing, the Borrower

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shall have the right, without the consent of the Lender, to remove and dispose
of, free from the Security Interest of this Agreement, such Collateral as from
time to time may become worn or obsolete or no longer usable in the Borrower's
business, provided that if any such Collateral is replaced with other property,
such other property shall be deemed to be subject to this Amended and Restated
Security Agreement.

            (e) That the Borrower shall have and maintain insurance at all times
with respect to all Collateral against risks of fire (including so-called
extended coverage), theft, and other risks as the Lender may require and, in the
case of motor vehicles, collision, and provide the Lender with a copy of such
policies containing such terms, in such form, for such periods and written by
such companies as may be satisfactory to the Lender, such insurance naming the
Lender as an additional insured or loss payee; that all policies of insurance
shall provide for thirty (30) days' written minimum cancellation notice to the
Lender and at the request of the Lender shall be delivered to and held by the
Lender; and that the Lender may act as attorney-in-fact for the Borrower in
obtaining, adjusting, settling and cancelling such insurance and endorsing any
drafts in accordance with the terms and conditions set forth in the December and
September Loan Agreements.

            (f) That the Borrower shall keep the Collateral free and clear of
any lien, security interest or encumbrance other than that granted herein and
those set forth in the attached Schedule B, and in good order and repair and
shall not waste or destroy the Collateral in violation of any statute or
ordinance; and that the Lender may examine and inspect the Collateral during
normal business hours at any time, wherever located, in accordance with Section
5.01(f) of the December and September Loan Agreements.

            (g) That the Borrower shall pay promptly when due all taxes and
assessments upon the Collateral or for its use or operation, except as otherwise
provided pursuant to Section 5.02(a)(ii) of the December and September Loan
Agreements.

            (h) That the Borrower is a corporation duly organized and existing
under the laws of the State of Florida, that the execution, delivery and
performance hereof are within the Borrower's corporate powers, have been duly
authorized, are not in contravention of any law, the Borrower's charter, bylaws,
or any indenture or undertaking to which the Borrower is a party or

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by which it is bound.

            (i) That at the time any account receivable becomes subject to a
Security Interest in favor of the Lender said account shall be a good and valid
account representing an undisputed, bona fide indebtedness incurred by the
account debtor named therein (the "Account Debtor") for merchandise held subject
to delivery instructions or theretofore shipped or delivered pursuant to a
contract of sale, or for services theretofore performed by the Borrower with or
for the Account Debtor; no agreement under which any extraordinary deduction or
discount may be claimed shall have been made with the Account Debtor of any such
account except as disclosed in writing to the Lender; and the Borrower shall be
the lawful owner of all such accounts and shall have good right to pledge, sell,
assign and transfer the same and to subject the same to a Security Interest in
favor of the Lender. No such account shall have been or shall thereafter be
sold, assigned or transferred to any person other than the Lender or in any way
encumbered except to the Lender and the Borrower shall defend the same against
the lawful claims and demands of all persons.

            (j) That the Borrower shall immediately notify the Lender of all
cases involving the return, rejection, repossession, loss or damage of or to
merchandise covered by accounts receivable, except in the ordinary course of the
Borrower's business; of any request for credit or adjustment or replacement
merchandise or other dispute arising with respect to accounts receivable, except
in the ordinary course of the Borrower's business; and generally of all
extraordinary happenings and events affecting accounts receivable or the value
or amount thereof, if, within sixty (60) days after the extraordinary event, the
matter at issue has not been satisfactorily resolved.

            (k) That the Borrower shall at all reasonable times and from time to
time allow the Lender, by or through any of its officers, agents or accountants,
to inspect the Collateral and to examine, inspect or make extracts from the
Borrower's books and records in accordance with Section 5.01(f) of the December
and September Loan Agreements and to arrange for verification of accounts
receivable, under reasonable procedures, directly with account debtors or by
other methods; shall furnish to the Lender upon request additional statements of
any accounts receivable, together with all notes or other papers evidencing the
same and any guaranty, securities or other documents or information

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relating thereto; shall furnish such reports, in form satisfactory to the
Lender, as to its accounts receivable as may be requested by the Lender under
this Amended and Restated Security Agreement or under the December and September
Loan Agreements, and shall perform, execute or deliver all such additional and
further acts, deeds, assurances and instruments as may be required to vest in
and assure to the Lender its perfected rights hereunder and in any Collateral.

         3. LENDER'S RIGHTS TO DISCHARGE ENCUMBRANCES, ETC. At its option,
either after an Event of Default has occurred and is continuing or after the
Borrower fails to take such action or make such payment or to contest such
action or payment in good faith as hereinafter stated within fifteen (15) days
after notice thereof given by the Lender to the Borrower, Lender may discharge
taxes, liens or security interests or other third party encumbrances at any
times levied or placed on the Collateral, and may pay for insurance and the
maintenance and preservation of the Collateral; provided that, if Borrower
contests such action or payment and Borrower reserves for any such potential
liability in accordance with standard accounting practices the Lender shall not
have the right to discharge such lien. The Lender shall have no obligation to
the Borrower to make any such expenditures nor shall the making thereof relieve
the Borrower of any default provision contained in this Amended and Restated
Security Agreement, the December Loan Agreement, the note evidencing the
December Loan (the "December Note"), or any other Loan Document (as hereinafter
defined) or contained in the September Loan Documentation or the July Loan
Documentation. Any such payments made under this Paragraph 3 and not reimbursed
by the Borrower within ten (10) days of demand therefor shall be added to the
outstanding principal balance of the December or September Loans, at the
Lender's option. The total amount of additional payments so made by the Lender
and not otherwise reimbursed by the Borrower shall be secured by this Amended
and Restated Security Agreement in the same manner as this Amended and Restated
Security Agreement secures the repayment of the Indebtedness.

         4. RIGHTS PRIOR TO DEFAULT. Until an Event of Default, the Borrower may
have possession of the Collateral and use it in any lawful manner not
inconsistent with this Amended and Restated Security Agreement, the December or
September Loan Agreement or any other Loan Documents or the September Loan
Documentation, and not inconsistent with any policy of insurance thereon.

         5. DEFAULT. The Borrower shall be in default under this

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Amended and Restated Security Agreement upon the happening (an "Event of
Default") of any of the following events or conditions:

            (a) failure to make any payments within ten (10) days after such
payment is due, or failure to perform any of the obligations required, or comply
with any covenant, under this Amended and Restated Security Agreement within
thirty (30) days after notice thereof has been given by Lender to Borrower;

            (b) the occurrence of any event of default (and the expiration of
applicable cure periods, if any) by the Borrower under any of the instruments
executed in connection with the December Loan, which instruments include,
without limitation, the December Loan Agreement, the December Note, the Amended
and Restated Patent, Trademark and License Security Agreement of even date
herewith (the "Amended and Restated Patent Security Agreement"), the Second
Amended and Restated Registration Rights Agreement of even date herewith (the
"Second Amended and Restated Registration Rights Agreement") and such other
documentation as may be executed in connection with the December Loan together
with any subsequent amendments or modifications thereto (collectively, the "Loan
Documents"); or

            (c) the occurrence of any event of default (and the expiration of
applicable cure periods, if any) by the Borrower under the September Note, the
September Loan Agreement and the September Loan Documentation, as amended and/or
restated.

         6. RIGHTS OF LENDER UPON DEFAULT. (a) Without limiting the rights of
the Lender as contained in the December and September Loan Agreements and the
Amended and Restated Patent Security Agreement, upon an Event of Default and at
any time thereafter (a "Post-Default Period") the Lender shall have the remedies
of a secured party under the Connecticut Uniform Commercial Code, or the law of
another jurisdiction if it shall be applicable, including, without limitation,
the right to take possession of the Collateral, and for that purpose the Lender
may, without legal process, so far as the Borrower can give authority therefor,
enter upon any premises on which the Collateral or any part thereof may be
situated and remove the same therefrom, provided such entry shall be done
lawfully. During a Post-Default Period, the Borrower shall, at the request of
the Lender, notify the Account Debtors of the Security Interest of the Lender in
any account, and will indicate on all billings to the Account Debtors that the
accounts are payable to the Lender. Notwithstanding the foregoing sentence, the
Lender may so notify

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the Account Debtors during a Post-Default Period of the Security Interest of the
Lender in any account, and direct the Account Debtors to pay the accounts to the
Lender. Any proceeds of accounts thereafter received by the Borrower shall be
turned over to the Lender daily in the exact form in which they are received.

            (b) The Lender may require the Borrower during a Post-Default Period
to assemble the Collateral and make it available to the Lender at a place to be
designated by the Lender which is reasonably convenient to both parties. Unless
the Collateral is perishable or threatens to decline rapidly in value or is of a
type customarily sold on a recognized market, the Lender will give the Borrower
reasonable notice of the time and place of any public sale thereof or of the
time after which any private sale or any other intended disposition thereof is
to be made. The requirements of reasonable notice shall be met if such notice is
mailed, postage prepaid, to the address of the Borrower shown in paragraph 2(b)
hereof at least five days before the time of the scheduled sale or disposition.
The Borrower shall be and remain liable for any deficiency remaining after
applying the proceeds of disposition first to the reasonable expenses of
repossessing, holding, preparing for and executing the sale, reasonable
attorney's fees and legal expenses incurred by the Lender in connection
therewith, and then to the satisfaction of the indebtedness secured hereunder.

         7. PERFECTION. (a) The Security Interest granted herein shall, to the
extent provided by applicable law, be perfected by the filing of a UCC-1
Financing Statement, duly executed by the Borrower and the Lender, with the
Secretary of the State of Florida, and any other filing office which the Lender
in its sole discretion deems appropriate. The failure of Lender at any time to
perfect its Security Interest in any part of the Collateral shall not constitute
a waiver of its right to perfect such interest at a later date. Borrower shall
cooperate in all respects with Lender in the perfection of Lender's Security
Interests granted herein or in any other Loan Document, including without
limitation executing such other financing statements, notices and documents and
furnishing to Lender such other information as Lender shall request in order to
perfect its Security Interest in any of the Collateral.

            (b) At the request of Lender made at any time during the term of the
December Loan, the September Loan or the July Loan for any reason, Borrower
shall execute a mortgage and

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conveyance of patents, trademarks, licenses and other proprietary rights in
favor of Lender, in form acceptable for filing with the U.S. Patent and
Trademark Office in accordance with 35 U.S.C. ss.261. Such mortgage and
conveyance shall be on substantially the same terms as the Amended and Restated
Patent Security Agreement, except that such mortgage and conveyance shall
provide for the absolute mortgaging and conveyancing of such rights, subject to
defeasance by Borrower upon payment of the indebtedness and the satisfaction of
the obligations hereby secured. Lender is hereby authorized to file such
mortgage and conveyance with the U.S. Patent and Trademark Office.

            (c) Borrower hereby irrevocably constitutes and appoints the Lender,
with full power of substitution, as its true and lawful attorney-in-fact, with
power, in the name of the attorney-in-fact or in the name of Borrower, to take
action on its behalf in carrying out the terms of this Section 7, including
without limitation to execute and record financing statements and to execute and
record with the U.S. Patent and Trademark Office a mortgage and conveyance of
patents, trademarks, licenses and other proprietary rights in favor of Lender as
provided herein. Lender hereby acknowledges that this grant of a
power-of-attorney is coupled with an interest and ratifies all that such
attorney shall lawfully do or cause to be done by virtue hereof. This power of
attorney shall be irrevocable until the Indebtedness secured hereby shall have
been paid in full and all financing arrangements between Borrower and Lender
with respect to the December Loan, the September Loan and the July Loan have
been terminated. Borrower acknowledges and agrees that the grant of this power
of attorney is not intended to limit or restrict in any way the rights and
remedies of Lender under the other Loan Documents, the September Loan
Documentation or the July Loan Documentation, but rather is intended to
facilitate the exercise of such rights and remedies.

         8. FORBEARANCE NOT A WAIVER. No forbearance on the part of the Lender
to take action upon an Event of Default shall operate as a waiver of any other
Event of Default or of the same Event of Default on a future occasion.

         9. MODIFICATION. This Amended and Restated Security Agreement may not
be modified or amended except by a writing signed by both the Borrower and the
Lender.

         10. AMENDED AND RESTATED PATENT SECURITY AGREEMENT. This Agreement is
supplemental to the Amended and Restated Patent

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Security Agreement, and the Lender may exercise its rights under both agreements
collectively or under each agreement independent of the other.

         11. SEVERABILITY. A provision of this Amended and Restated Security
Agreement deemed invalid or unenforceable under any applicable law shall not
serve to invalidate the remainder of this Amended and Restated Security
Agreement.

         12. CONSTRUCTION. This Amended and Restated Security Agreement and all
rights and obligations hereunder, including matters of construction, validity
and performance, shall be governed by the laws of the State of Connecticut.

         13. BINDING EFFECT. All rights of the Lender hereunder shall inure to
the benefit of its successors and assigns, and all obligations of the Borrower
shall bind its heirs, personal representatives, successors and assigns.

         14. HEADINGS. Headings are for convenience only and shall not be deemed
part of this Amended and Restated Security Agreement.

         15. BORROWER WAIVERS. THE BORROWER ACKNOWLEDGES THAT THE TRANSACTION OF
WHICH THIS AMENDED AND RESTATED SECURITY AGREEMENT IS A PART IS A COMMERCIAL
TRANSACTION AND MAKES THE FOLLOWING WAIVERS:

                  A. THE BORROWER HEREBY WAIVES, TO THE FULLEST 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 LAWS.

                  B. THE BORROWER HEREBY WAIVES THE RIGHT TO A JURY TRIAL.

                  C. THE BORROWER HEREBY CONSENTS TO THE JURISDICTION OF ANY
         LOCAL, STATE, OR FEDERAL COURT LOCATED WITHIN THE STATE OF FLORIDA OR
         CONNECTICUT AND WAIVES ANY OBJECTION WHICH THE 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
         IN SECTION 8.02 OF THE DECEMBER LOAN

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         AGREEMENT AND SECTION 9.02 OF THE SEPTEMBER LOAN AGREEMENT 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 THE 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 SECTION 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 THE BORROWER OR BORROWER'S PROPERTY IN THE COURTS OF ANY OTHER
         JURISDICTION.

                  D. THE BORROWER HEREBY AGREES NOT TO COMMENCE ANY LEGAL
         PROCEEDING AGAINST THE LENDER IN THE JURISDICTION OF ANY LOCAL, STATE,
         OR FEDERAL COURT LOCATED WITHIN THE STATE OF FLORIDA UNLESS THE LENDER
         EXPRESSLY CONSENTS THERETO IN WRITING.

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         IN WITNESS WHEREOF, the parties have signed and delivered this
agreement on the day and year first above written.

                                     BORROWER:

                                     KOS PHARMACEUTICALS, INC.

                                     By_______________________________________
                                       Name:   Daniel M. Bell
                                       Title:  President

                                     LENDER:

                                     ________________________________
                                     MICHAEL JAHARIS

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                                   SCHEDULE A

DEBTOR/BORROWER: KOS PHARMACEUTICALS, INC.
SECURED PARTY/LENDER: MICHAEL JAHARIS

For purposes of this Amended and Restated Security Agreement, the term
"Collateral" shall mean all right, title and interest in and to any and all
tangible property (other than real property), accounts, accounts receivable and
contract rights, inventory, equipment and machinery, trademarks, trade names and
service marks, patents, licenses, chattel paper, instruments, documents, letters
of credit and general intangibles, and whether now owned or hereafter acquired
by the Borrower (to be used interchangeably with the term "Debtor" as that term
is defined or understood under the Connecticut Uniform Commercial Code) wherever
located, and any additions and accessions thereto and replacements and renewals
thereof, and all proceeds of any of the foregoing, including, without
limitation:

1.       ACCOUNTS - All presently owned and hereafter acquired accounts,
         accounts receivable, contract rights, bills, acceptances, and other
         forms of obligations arising out of the sale, lease or consignment of
         goods or the rendition of services by the Borrower; together with any
         property evidencing or relating to the Accounts (such as guaranties,
         credit insurance, Letters of Credit), any security for the Accounts,
         all books and records relating thereto, and all Proceeds of any of the
         foregoing, including returned or reclaimed inventory.

2.       INVENTORY - All presently owned and hereafter acquired inventory of
         every nature, kind, and description, wherever located, including,
         without limitation, raw materials, goods, work in process, finished
         goods, parts or supplies; all goods and property held for sale or lease
         or to be furnished under contracts of service; and all goods and
         inventory returned, reclaimed or repossessed, together with all
         Proceeds of any of the foregoing.

3.       EQUIPMENT - All presently owned and hereafter acquired equipment,
         whether or not affixed to realty, including, without limitation,
         trucks, trailers, motors, tools, dies, parts, jigs, goods, accessories,
         handling and delivery equipment, fixtures, improvements, office
         machines and furniture, together with all Proceeds of any of the
         foregoing, and all accessions, accessories, replacements and

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         the rights of the Borrower under any manufacturer's warranties relating
         to the foregoing.

4.       CHATTEL PAPER - All presently owned and hereafter acquired chattel
         paper, including, but not limited to, any writing or writings which
         evidence both a monetary obligation and a security interest in or a
         lease of specific goods, together with all Proceeds of any of the
         foregoing.

5.       INSTRUMENTS - All presently owned and hereafter acquired instruments,
         including, without limitation, bills of exchange, notes, and all
         negotiable instruments, all certificated securities, all certificates
         of deposit and any other writing which evidences a right to the payment
         of money and is not itself a security agreement or lease and is of a
         type which is in the ordinary course of business transferred by
         delivery with any necessary endorsement or assignment, together with
         all Proceeds of any of the foregoing.

6.       DOCUMENTS - All presently owned and hereafter acquired documents,
         including, but not limited to, documents of title (as that term is
         defined in the Uniform Commercial Code) and any and all receipts,
         including, but not limited to, receipts of the kind described in
         Article 7 of the Connecticut Uniform Commercial Code, together with all
         Proceeds of any of the foregoing.

7.       LETTERS OF CREDIT - All letters of credit under which Borrower is or
         hereafter will be the customer or the beneficiary, including, but not
         limited to, any written undertaking to pay money conditioned upon
         presentation of specified documents, and advices of letters of credit,
         together with all Proceeds of any of the foregoing.

8.       GENERAL INTANGIBLES - All presently owned and hereafter acquired
         general intangibles, including, without limitation, any personal
         property, choses in action, causes of action, designs, plans, Goodwill,
         tax refunds, Licenses, franchises, Patents, Trademarks, trade secrets,
         know-how, rights of Borrower to and interests of Borrower in research
         and development of the Borrower, copyrights, and customer lists, and
         all rights under license agreements for use of the same, together with
         all Proceeds of any of the foregoing.

9.       PATENTS - All presently owned and hereafter acquired patents

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         and patent applications, including, without limitation, the inventions
         and improvements described and claimed therein, those patents listed on
         Schedule A-1 attached hereto and made a part hereof, and any and all
         patents, patent applications and other rights and interests in and to
         the Borrower's products Niaspan(R)and Nicostatin(R), and (a) the
         reissues, divisions, continuations, renewals, extensions and
         continuations-in-part thereof, (b) all income, royalties, damages and
         payments now and hereafter due and/or payable under and with respect
         thereto, including, without limitation, damages and payments for past
         or future infringements thereof, (c) the right to sue for past, present
         and future infringements thereof, and (d) all rights corresponding
         thereto throughout the world.

10.      TRADEMARKS - trademarks, service marks, trademark registrations,
         service mark registrations, trade names and trademark registrations,
         including, without limitation, the trademarks/service marks Niaspan(R)
         and Nicostatin(R), and (a) renewals or extensions, thereof, (b) all
         income, royalties, damages and payments now and hereafter due and/or
         payable with respect thereto, including, without limitation, damages
         and payments for past or future infringements thereof, (c) the right to
         sue for past, present and future infringements thereof, and (d) all
         rights corresponding thereto throughout the world.

11.      LICENSES - license agreements with any other party, whether Borrower is
         a licensor or licensee under any such license agreement, and the right
         to prepare for sale, sell and advertise for sale, all Inventory now or
         hereafter owned by Borrower and now or hereafter covered by such
         licenses.

12.      GOODWILL - the goodwill of Borrower's business connected with and
         symbolized by the Trademarks.

13.      PROCEEDS - All presently owned and hereafter acquired proceeds, as that
         term is defined in the Connecticut Uniform Commercial Code, including,
         without limitation, whatever is received upon the use, lease, sale,
         exchange, collection, any other utilization or any disposition of any
         of the Collateral described on this Schedule A, whether cash or
         non-cash, all rental or lease payments, accounts, chattel paper,
         instruments, documents, contract rights, general intangibles,
         equipment, inventory, substitutions, additions, accessions,
         replacements, products, and renewals of, for, or

                                       15
<PAGE>

         to such property and all insurance therefor.

                                       16EXHIBIT 10.19

$ 50,000,000.00                                               New York, New York
                                                              December 21, 1999

1. OBLIGATION TO PAY

         FOR VALUE RECEIVED, the undersigned Borrower promises to pay to the
order of MICHAEL JAHARIS, an individual residing in South Norwalk, Connecticut
(the "Lender"), the principal sum of Fifty Million Dollars ($50,000,000.00), on
June 30, 2005, 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 Note, plus any costs and expenses incurred in the enforcement of this
Note as provided in paragraph 7 of this Note. This Note is transferable by the
holder hereof.

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

2. DEFINITIONS

         Except as otherwise defined herein, all capitalized terms used herein
which are defined in the 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 Note and the Loan Agreement.

         (d) "Interest Adjustment Date" shall mean the first day of each month
during the term of this Note.

                                        1
<PAGE>

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

         (f) "Loan Documents" shall mean this Note, the Loan Agreement, the
Second Amended and Restated Registration Rights Agreement, the Amended and
Restated Security Agreement, the Amended and Restated Patent Security Agreement,
the Amended and Restated Stock Pledge Agreement, the Amended and Restated
Subsidiary Guaranty, the Amended and Restated Subsidiary Security Agreement, the
IEP Guaranty, the IEP Security Agreement, the UCC-1 financing statements
executed in connection with the security agreements, the Warrant Agreement, 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 "Loan Document".

         (g) "Prime Rate" shall mean the prime rate (or substantially equivalent
index, if such bank discontinues its prime rate) of First Union National Bank 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 warrant to purchase 6 million
shares of Common Stock at a price of $5.00 per share.

3. INTEREST

         The outstanding principal balance of this 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

                                       2
<PAGE>

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 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 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 Connecticut 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 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 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 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 Note in full or in part at any time without
penalty.

                                       3
<PAGE>

         All payments shall be made in accordance with the terms of the Loan
Agreement and shall 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 Note may also be prepaid in part or in full by the holder of this
Note exercising the Warrant in accordance with the terms of the Warrant. No
partial prepayment of this Note by exercise of the Warrant shall abate
Borrower's obligation to make monthly interest payments on the outstanding
amount under this Note, nor shall such partial prepayment extend the maturity
date of this Note.

5. ADVANCES

         Advances shall be made hereunder from time to time in accordance with
terms of the 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 $50,000,000.00.

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 Loan
Agreement and shall be entitled to be reimbursed for its costs and expenses as
set forth therein.

                                       4
<PAGE>

         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 Note;
or (iii) the occurrence of any Event of Default under the Loan Agreement.

         No extension of time for payment, or delay in enforcement hereof, nor
any renewal of this 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 Note
or the Loan Agreement, irrespective of whether or not the Lender shall have made
any demand under this Note or the 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.

9. WAIVER OF RIGHTS

    BORROWER ACKNOWLEDGES THAT THE TRANSACTION OF WHICH THIS 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

                                       5
<PAGE>

         THE BORROWER HEREBY CONSENTS TO THE JURISDICTION OF ANY LOCAL, STATE,
OR FEDERAL COURT LOCATED WITHIN THE STATE OF CONNECTICUT 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 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
WITHIN THE STATE OF FLORIDA UNLESS THE LENDER EXPRESSLY CONSENTS THERETO IN
WRITING.

13. GOVERNING LAW

         This Note and its interpretation, construction, validity and
enforceability shall be governed by the laws of the State of Connecticut.

                                     KOS PHARMACEUTICALS, INC.

                                       6
<PAGE>

                                     By: _______________________________
                                     Name: Daniel M. Bell
                                     Title:     President

STATE OF          )
                  )  ss.:
COUNTY OF         )

         On the ______ day of __________ ___, ____, before me came Daniel M.
Bell, 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:

                                       7

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