<PAGE>
                                                                   EXHIBIT 10.37
                                                                     Page 1


                                   PROMISSORY NOTE


$948,089

Dated:   October 21, 1996    At:  South El Monte, California

         FOR VALUE RECEIVED, the undersigned LEE PHARMACEUTICALS, INC., a 
California corporation with its principal place of business located at 1444 
Santa Anita Avenue, South El Monte, California 91733 ("Maker"), promises to 
pay to the order of ROBERTS LABORATORIES INC., a New Jersey corporation with 
its principal place of business located at Meridian Center II, Four 
Industrial Way West, Eatontown, New Jersey 07724-2274 ("Lender"), the 
principal sum of Nine Hundred Forty-Eight Thousand Eighty Nine Dollars 
($948,089) (the "Principal sum"), with interest thereon at the rate equal to 
the prime rate as it may exist from time to time which is equal to the 
highest prime rate reported from time to time by the Wall Street Journal (but 
in no case more than any interest rate permitted by law) from the date set 
forth above, to be paid in lawful money of the United States of America, at 
Lender's address set forth above or such other place as Lender may from time 
to time designate in writing.  All references to Lender in this Note shall be 
deemed to mean and include any subsequent holder hereof.

    1.   PAYMENT OF PRINCIPAL AND INTEREST.  The indebtedness evidenced 
hereby shall be repaid in equal monthly installments of principal in the 
amount of Nineteen Thousand Seven Hundred Fifty-One Dollars and Eighty-Five 
Cents ($19,751.85) each, commencing on November 1, 1996 and continuing 
monthly thereafter until October 1, 2000 and one payment on November 1, 2000 
of the entire remaining principal balance then outstanding, plus all accrued 
and unpaid interest and all other applicable fees, costs and charges if any 
shall have been paid in full.  Interest shall accrue on all of the unpaid 
outstanding balance of the purchase price and shall be paid monthly 
commencing November 1, 1996, at a rate equal to the highest prime rate 
published in the Wall Street Journal during the month preceding the month in 
which the interest payment is due and continuing until the entire outstanding 
amount of the purchase price shall have been paid in full.  In no case, 
however, shall the interest rate be higher than that rate permitted by 
applicable law.

    2.   SECURITY.  This Note and all the obligations of Maker hereunder are 
secured by the security interests granted in the Security Agreement of even 
date herewith executed by Maker (the "Security Agreement").  This Note, and 
the Security Agreement, together with all other documents now or at any time 
hereafter creating, evidencing or securing the indebtedness evidenced by this 
Note, are herein referred to collectively as the "Loan Documents."

    3.   APPLICATION OF PROCEEDS.  Maker is giving this Note to Lender 
pursuant to an Asset Purchase and Sale Agreement of even date herewith 
between Maker and Lender (the "Asset Purchase Agreement") to purchase the 
Assets (as that term is defined in the Asset Purchase Agreement).

<PAGE>

                                                                   EXHIBIT 10.37
                                                                     Page 2


    4.   PREPAYMENT RIGHTS.  Maker shall have the right to prepay at any time 
and from time to time all or any portion of the entire principal balance of 
this Note and interest thereon, together with all other indebtedness 
evidenced hereby, without penalty, provided that Lender shall have received 
at least ten (10) days prior written notice of prepayment and Maker shall pay 
all accrued and unpaid interest thereon and all other fees and costs, if any, 
due to Lender under this Note.  Any partial prepayment will be applied first 
against any fees or charges due under the Loan Documents, if applicable, and 
then against accrued and unpaid interest and then against the principal of 
this Note.  No partial prepayment will excuse any future payment of principal 
or interest as long as any amounts remain unpaid.

    5.   DEFAULT PROVISIONS.  The occurrence of any one or more of the 
following events shall constitute an Event of Default under this Note:  (a) 
failure of Maker to pay when due any amount required to be paid; (b) the 
Maker shall be adjudicated a bankrupt or insolvent, or admit in writing its 
inability to pay its debts as they mature, or make an assignment for the 
benefit of creditors, or the Maker shall apply for or consent to the 
appointment of a receiver, trustee, or similar officer for it or for all or 
any substantial part of its property, or such receiver, trustee or similar 
officer shall be appointed without the application or consent of the Maker 
and such appointment shall continue undischarged for a period of ninety (90) 
days, or the Maker shall institute (by petition, application, answer, consent 
or otherwise) any bankruptcy, insolvency, reorganization, arrangement, 
readjustment of debt, dissolution, liquidation or similar proceeding relating 
to it under the laws of any jurisdiction, or any such proceeding shall be 
instituted (by petition, application or otherwise) against the Maker and 
shall remain undismissed for a period of ninety (90) days, or (c) any default 
under the Security Agreement; provided, however, that no Event of Default 
shall be deemed to have occurred if: (a) there continues to exist a good 
faith disagreement between Maker and Robert Laboratories, Inc. with respect 
to the proper amount payable by Maker in respect of this Note or (b) if there 
exists a good faith disagreement during the term of this Note regarding the 
Assets conveyed by Roberts Laboratories, Inc. as seller to Maker as purchaser 
under the Asset Purchase and Sale Agreement.  Whenever there is an Event of 
Default under this Note, Lender shall give Maker written notice of such Event 
of Default and if such Event of Default is not cured within 30 days of 
receipt of such written notice, Lender may, at its option, declare the unpaid 
balance of the principal amount, together with all accrued and unpaid 
interest and all other indebtedness evidenced hereby, to be immediately due 
and payable, and exercise any and all rights and remedies available to Lender 
hereunder, under applicable laws and under any of the other Loan Documents, 
all of which rights and remedies are cumulative.

    6.   PAYMENT OF COLLECTION COSTS.  If Lender requires the services of an 
attorney to enforce the payment of this Note or the performance of the other 
Loan Documents, or if this Note is collected through any lawsuit, bankruptcy, 
or other proceeding, Maker agrees to pay Lender an amount equal of reasonable 
attorneys' fees and other actual collection costs.

    7.   WAIVER OF CERTAIN RIGHTS OF MAKER.  As to this Note and the Security 
Agreement, and all other Loan Documents, the undersigned waives all 
applicable exemption

<PAGE>

                                                                   EXHIBIT 10.37
                                                                     Page 3


rights, whether under any State Constitution or otherwise, and also waives 
valuation and appraisement, presentment, protest and demand, notice of 
protest, demand and dishonor and nonpayment of this Note, and expressly 
agrees that the maturity of this Note, or any payment hereunder, may be 
extended from time to time without in any way affecting the liability of 
Maker.

    8.   NON-WAIVER OF CERTAIN RIGHTS OF HOLDER.  Any failure by the holder 
hereof to insist upon the strict performance of any of the terms and 
provisions of this Note or of any of the other Loan Documents shall not be 
deemed to be a waiver of any of the terms and provisions hereof, and the 
holder hereof, notwithstanding any such failure, shall have the right 
thereafter to insist upon the strict performance by maker of any and all of 
the terms and provisions of this Note and the other Loan Documents.

    9.   INVALIDITY OF PROVISIONS.  In the event that any one or more of the 
provisions contained in this Note or any of the other Loan Documents shall 
for any reason be held to be invalid, illegal or unenforceable in any 
respect, such invalidity, illegality or unenforceability shall not affect any 
other provision of this Note or any of the other Loan Documents, and each 
term and provision of this Note and the other Loan Documents shall be valid 
and enforceable to the fullest extent permitted by law.

    10.  AMENDMENTS MUST BE IN WRITING.  This Note may not be changed orally, 
but only by an agreement in writing signed by Maker.

    11.  GOVERNING LAW.  This Note is to be construed according to the laws 
of the State of California and shall be binding upon and inure to the benefit 
of Maker and Lender and their respective successors and assigns.

    12.  CAPTIONS.  The captions of this Note are for convenience only and 
shall neither limit nor enlarge the provisions hereof.

    Executed as of the day and year first above written.


                                              LEE PHARMACEUTICALS, INC.


                                              By:      Ronald G. Lee   
                                                 -----------------------------
                                                       Ronald G. Lee

                                              Title:    President and CEO

                                              Date:     October 21, 1996    
                                                   ---------------------------