<PAGE>

                        [LETTERHEAD OF BENNETT JONES]



November 26, 1999


Via Facsimile

Mr. Eugene M. Schloss, Jr.
Attorney at Law
1700 Cary Road
Huntingdon Valley, PA 19006 5002

Dear Gene:

Re:   Optopics Laboratories Corporation

Further to our clients' discussions of November 17, 1999 and our discussions of
November 22, 1999, we believe that NutraMax/Optopics and Miza can address the
following outstanding issues cooperatively so as to be in a position to close
the Optopics transaction in an expedient manner and in accordance with the terms
and conditions of the October 15, 1999 Purchase and Sale Agreement (the
"Agreement"). Please note that even though the items set out in paragraphs 2 to
5 below do not all have specific timelines, Miza believes that such items will
be completed on or before December 10, 1999. The items set out in paragraph 1
are, of course, the items which were specifically discussed by the parties and
are of utmost importance to Miza.

1.    The following outstanding regulatory compliance issues in respect of the
      Optopics facility are required to be dealt with by Optopics to Miza's
      reasonable satisfaction prior to closing:

      (a)    The Vitek Jr CC4/DT Computer Upgrade is scheduled as follows:
             - reports are being written: 11/24/99
             - final validation completion date: 11/30/99.

      (b)    The GC (Gas Chromatography) and UV-Vis (Diode Array
             Spectrophotometer)
             - we understand Hewlett Packard is scheduled to complete the
             validation on 12/09/99
             - we understand the equipment will be in compliance when they
             arrive to do the work and will be in compliance when they leave on
             that day.

      (c)    Requalification of the five micro incubators:
             - we understand all protocols have been written
             - we understand validations will be conducted by Mike Morrelli by
             12/03/99.
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November 26, 1999
Page Two

      (d)    Media Fill for fill room 1
             - we understand media fill is being run today: 11/24/99.

2.    Installation and testing of the USP Water System:
      - we understand installation of system completed: 11/23/99
      - we understand testing completed: 12/02/99
      - we understand final test results completed: 12/07/99.

3.    The following transition matters need to be completed:

      (a)    Notification of Customers:
             - we understand NutraMax has already communicated with its
             customer base related to the sale of assets, and NutraMax
             would be willing to provide (if feasible) mailing labels to
             Miza if they choose to perform a mailing to the customers.

      (b)    Labels, prints, graphic material
             - we understand the above information is being loaded on a zip
             drive so it can be provided to Miza on the date of closing.

      (c)    The Finished Goods inventory at Gloucester should be
             identified so that Miza can complete its inspection at least a
             day before closing; we understand that our respective clients
             are currently coordinating the process for taking inventory
             and will continue to do so up to closing;

      (d)    Data download:

             The download of all applicable data bases and applications
             necessary to run the Optopics business, including documentation on
             customizations that NutraMax has done to systems including
             Optopics' customer history/data from Symix (or Syteline depending
             on the application that NutraMax is utilizing at closing) to Miza's
             database. The parties have agreed to utilize "Decision Resources"
             (Miza's Symix/Syteline consulting group) to mediate this transfer;
             we understand that Decision Resources will be able to separate the
             Optopics data from the NutraMax data subject to appropriate
             confidentiality obligations in favour of NutraMax;

             - we understand download of all applicable data bases and
             applications will be conducted on the day of closing provided Miza
             has a server in place to receive the data and files. The
             transmission will be done electronically and can be executed upon
             request.

      (e)    Documentation of the current Optopics' customer order processing
             system as handled by NutraMax is required; we understand that this
             work has begun.

4. The following human resources issues need to be finalized:


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November 26, 1999
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      (a)    All Optopics employees will be terminated effective on closing
             and all required payments shall be made to them by Optopics on
             closing;

      (b)    The distribution of funds for the 401(k) and section 125 plan will
             be made according to the terms of the respective plans and
             applicable law and regulations;

      (c)    All benefits including, but not limited to, medical insurance,
             dental insurance and group life insurance will terminate at
             midnight on the date of termination as per company policy and the
             terms of the respective Plans. Eligible employees will have the
             option COBRA as per applicable law and regulations.

      We understand Dr. Kachkar's consultant, Burt Bartzhoff, is finalizing all
      such matters with Optopics' Carol Woloss in the Human Resources
      Department.

5.    Leased space:

      Optopics is leasing warehouse space in Bridgeton, New Jersey for obsolete
      raw material inventory. As Miza is not purchasing this inventory Optopics
      needs to assign someone to handle its removal from the Bridgeton location.

      - we understand NutraMax intends to remove the product from the leased
      space prior to closing.

We would like to highlight that NutraMax/Optopics have been very helpful and
supportive during this entire process in the interest of an orderly closing of
the transaction. The recent PLMA show in Chicago demonstrated to us that the
NutraMax/Optopics customers and vendors are aware of and supportive of the
transaction. This is of course good news and underscores Miza's commitment to
helping you preserve the business in anticipation of closing.

Miza advises that, to the best of its knowledge, it will be in a position, on or
before closing, to satisfy or comply with the Miscellaneous Provisions imposed
by its banker attached hereto as Exhibit "A".

Subject to the provisions of the Agreement, Miza considers that the foregoing
items constitute an exhaustive list of the issues respecting the contemplated
transaction. It appears therefore that Optopics and Miza will be in a position
to close immediately upon completion of all of the above items. The parties
accordingly agree to amend the Agreement to extend the Closing Date to December
10, 1999. In anticipation of such closing the parties shall hold a pre-closing
on December 9, 1999 at the offices of Ballard Spahr Andrews & Ingersoll, LLP
where all tabled documents shall be held in escrow
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November 26, 1999
Page Four


pending the closing on December 10, 1999. If you agree with the foregoing please
execute a copy of the enclosed letter and return to us by fax today with a hard
copy to follow. I provide this letter to you on behalf of my client.

Yours truly,

BENNETT JONES



Enzo J. Barichello

EJB/ark
cc:      Mr. David Radeke (via facsimile: 978-282-3794)
         Dr. Jack Kachkar

------------------------------------------------------------------------------

Acknowledged and Agreed to by Optopics Laboratories Corporation this 26/th/ day
of November, 1999.
                                             OPTOPICS LABORATORIES
                                             CORPORATION

                                             Per: /s/ David J. Radeke
                                                 ---------------------------
                                             Name:  David J. Radeke
                                             Title: Executive Vice President and
                                                    Chief Operating Officer