EXHIBIT (a)(6)


                          OFFER TO PURCHASE FOR CASH
                ALL OUTSTANDING SHARES OF CLASS A COMMON STOCK
                                      OF
                   CHESAPEAKE BIOLOGICAL LABORATORIES, INC.
                                       AT
                              $4.60 NET PER SHARE
                                      BY
                        AC ACQUISITION SUBSIDIARY, INC.
                           A WHOLLY OWNED SUBSIDIARY
                                      OF
                              CANGENE CORPORATION

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THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT, NEW YORK CITY
            TIME, ON JANUARY 3, 2001, UNLESS THE OFFER IS EXTENDED.
- -------------------------------------------------------------------------------

                                November 17, 2000


To Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees:

     AC Acquisition Subsidiary, Inc., a Maryland corporation (the "Purchaser")
and a wholly owned subsidiary of Cangene Corporation, a Canadian corporation,
has commenced an offer to purchase all of the issued and outstanding shares of
class A common stock, par value $.01 per share (the "Shares") of Chesapeake
Biological Laboratories, Inc., a Maryland corporation (the "Company"), at a
price of $4.60 per Share, net to the seller in cash, less any required
withholding of taxes and without payment of any interest, upon the terms and
subject to the conditions set forth in the Offer to Purchase, dated November
17, 2000 (the "Offer to Purchase") and in the related Letter of Transmittal
(which, together with any amendments or supplements thereto, constitute the
"Offer"). Please furnish copies of the enclosed materials to those of your
clients for whose accounts you hold Shares registered in your name or in the
name of your nominee.

     The offer is conditioned upon, among other things, the satisfaction or
waiver of certain conditions to the obligations of Purchaser and the Company to
consummate the offer, including (1) there being validly tendered and not
withdrawn prior to the expiration of the Offer at least a majority of the
issued and outstanding shares (including shares into which the Company's series
A-1 convertible preferred stock is convertible and the shares for which the
Company's warrants are exercisable), (2) receipt by Purchaser and the Company
of certain governmental and regulatory approvals, and (3) the loan commitment
from The Bank of Nova Scotia not being withdrawn.

     For your information and for forwarding to your clients for whom you hold
Shares registered in your name or in the name of your nominee or who hold
Shares registered in their own names, we enclose the following documents:

     1. Offer to Purchase, dated November 17, 2000.

     2. Letter of Transmittal to tender Shares for your use and for the
information of your clients. Facsimile copies of the Letter of Transmittal may
be used to tender Shares.

     3. Letter to Clients, which may be sent to your clients for whose account
you hold Shares registered in your name or in the name of your nominee, with
space provided for obtaining such clients' instructions with regard to the
Offer.



     4. Notice of Guaranteed Delivery to be used to accept the Offer if Share
Certificates (as defined in the Offer to Purchase) are not immediately
available or time will not permit the Share Certificates and all required
documents to reach the Depositary on or prior to the Expiration Date (as
defined in the Offer to Purchase) or if the procedures for delivery by
book-entry transfer, as set forth in the Offer to Purchase, cannot be completed
on a timely basis.

     5. Letter to stockholders of the Company from Thomas P. Rice, the
President and Chief Executive Officer of the Company, accompanied by the
Company's Solicitation/Recommendation Statement on Schedule 14D-9.

     6. Guidelines for Certification of Taxpayer Identification Number on
Substitute Form W-9.

     7. Return envelope addressed to The Bank of New York, as Depositary.

     In accordance with the terms and subject to the satisfaction or waiver
(where applicable) of the conditions to the Offer, Purchaser will accept for
payment, purchase and pay for, all Shares which have been validly tendered and
not withdrawn pursuant to the Offer at the earliest time following expiration
of the Offer that all such conditions shall have been satisfied or waived
(where applicable). For purposes of the Offer, Purchaser will be deemed to have
accepted for payment (and thereby purchased), Shares validly tendered and not
withdrawn if, as and when Purchaser gives oral or written notice to the
Depositary of Purchaser's acceptance for payment of such Shares pursuant to the
Offer. Upon the terms and subject to the conditions of the Offer, payment for
Shares accepted for payment pursuant to the Offer will be made only after
timely receipt by the Depositary of (1) the Share Certificates or a Book-Entry
Confirmation (as defined in the Offer to Purchase) of a book-entry transfer of
such Shares into the Depositary's account at the Book-Entry Transfer Facility
(as defined in the Offer to Purchase) pursuant to the procedures set forth in
Section 3 of the Offer to Purchase; (2) the Letter of Transmittal (or a
facsimile thereof) properly completed and duly executed, with any required
signature guarantees, or, in the case of a book-entry transfer, an Agent's
Message (as defined in the Offer to Purchase) in lieu of the Letter of
Transmittal; and (3) any other documents required under the Letter of
Transmittal.

     Purchaser will not pay any commissions or fees to any broker, dealer or
other person (other than the Depositary and the Information Agent (as described
in the Offer to Purchase)) in connection with the solicitation of tenders of
Shares pursuant to the Offer. Purchaser will, however, upon request, reimburse
you for customary clerical and mailing expenses incurred by you in forwarding
any of the enclosed materials to your clients.

     Purchaser will pay any stock transfer taxes with respect to the transfer
and sale of Shares to it or to its order pursuant to the Offer, except as
otherwise provided in Instruction 6 of the enclosed Letter of Transmittal.

     YOUR PROMPT ACTION IS REQUESTED. WE URGE YOU TO CONTACT YOUR CLIENTS AS
PROMPTLY AS POSSIBLE. PLEASE NOTE THAT THE OFFER AND WITHDRAWAL RIGHTS EXPIRE
AT 12:00 MIDNIGHT, NEW YORK CITY TIME, JANUARY 3, 2001, UNLESS THE OFFER IS
EXTENDED.

     In order for a stockholder of the Company to take advantage of the Offer,
the Letter of Transmittal (or a facsimile thereof), properly completed and duly
executed, together with any required signature guarantees (or, in the case of a
book-entry transfer, an Agent's Message in lieu of the Letter of Transmittal)
and any other documents required by the Letter of Transmittal should be sent to
the Depositary and Share Certificates should be delivered, or Shares should be
tendered pursuant to the procedure for book-entry transfer, all in accordance
with the instructions set forth in the Letter of Transmittal and the Offer to
Purchase.

     Holders of Shares whose Share Certificates are not immediately available
or who cannot deliver their Share Certificates and all other required documents
to the Depositary on or prior the Expiration Date of the Offer, or who cannot
complete the procedure for delivery by book-entry transfer on a timely basis,
must tender their Shares according to the guaranteed delivery procedures set
forth in Section 3 of the Offer to Purchase.



     Any inquiries you may have with respect to the Offer should be addressed
to, and additional copies of the Offer to Purchase, the Letter of Transmittal
and all other tender offer materials may be obtained from, the Information
Agent at its address and telephone number set forth on the back cover of the
Offer to Purchase.



                     Very truly yours,



                     AC Acquisition Subsidiary, Inc.



     NOTHING CONTAINED HEREIN OR IN THE ENCLOSED DOCUMENTS SHALL CONSTITUTE YOU
OR ANY OTHER PERSON AS AN AGENT OF PURCHASER, THE DEPOSITARY OR THE INFORMATION
AGENT, OR ANY AFFILIATE OF ANY OF THEM, OR AUTHORIZE YOU OR ANY OTHER PERSON TO
MAKE ANY STATEMENT OR USE ANY DOCUMENT ON BEHALF OF ANY OF THEM IN CONNECTION
WITH THE OFFER OTHER THAN THE ENCLOSED DOCUMENTS AND THE STATEMENTS CONTAINED
THEREIN.