full force provided, however, that if without such invalid or unenforceable provision the fundamental mutual objectives of the parties cannot be achieved, either party may terminate this Agreement without penalty by written notice to the other. 5.10. Interest. Any overdue amounts payable hereunder will bear interest, payable on demand (whether before or after judgment), from due date to date of payment, at an annual rate of two percent (2%) above the prime rate of Citibank, N.A. in effect on the due date or, if lower, the maximum rate permitted by applicable law. 5.11. Miscellaneous. Each party will bear its own expenses in connection with the negotiation, preparation and execution of this Agreement. The headings of the paragraphs and subparagraphs of this Agreement have been added for the convenience of the parties and are not be deemed a part hereof. This Agreement may be executed in any number of counterparts, all of which together constitute a single agreement. In proving this Agreement, it will not be necessary to produce or account for more than one counterpart signed by the party with respect to which proof is sought. This Agreement is the sole understanding and agreement of the parties with respect to its subject matter and supersedes all other such prior or contemporaneous oral and written agreements and understandings. Signed, sealed and delivered by a duly authorized representative of each party hereto as of the date first written above. THE BUTLER COMPANY BIOPURE CORPORATION By: By: -------------------------------- -------------------------------- Andrew W. Wright, Title: Vice President, Veterinary ----------------------------- Products Address: Address: 11 Hurley Street --------------------------- Cambridge, MA 02141 Telecopy No.: (617) 234-6507 --------------------------- --------------------------- 16 EXHIBIT A BIOPURE CORPORATION Oxyglobin(R) Brand Products Price List (Introductory Promotional Pricing*) Each Box contains two 125 ml bags of Oxyglobin(R) Brand Veterinary Product. Retail Price Retail Price Per