AMENDMENT TO EMPLOYMENT AGREEMENT
This Amendment to Employment Agreement (this "Amendment"), made as of the 10th day of July, 2001, is
entered into by The Medicines Company, a Delaware corporation with its principal place of business at One
Cambridge Center, Cambridge, Massachusetts 02142 (the "Company"), and David Stack, residing at One Robin
Drive, Oak Ridge, New Jersey 07438 (the "Employee").
WHEREAS, the Company and the Employee are parties to an Employment Agreement dated as of April 1,
2000, as amended (the "Employment Agreement"); and
WHEREAS, the Company and the Employee desire to make certain amendments to the terms of the
Employment Agreement to reflect the Employee's agreement to devote his full business time to the Company;
NOW THEREFORE, in consideration of these premises, the mutual covenants and promises contained herein,
and other good and valuable consideration, the receipt and sufficiency of which are acknowledged, the parties
hereto agree as follows:
I. Employment Agreement
1. Defined Terms. The capitalized terms used herein but not otherwise defined shall have the meanings assigned
to them in the Employment Agreement.
2. Title; Capacity. The Employment Agreement is hereby amended by deleting Section 2 of the Employment
Agreement in its entirety and inserting in lieu thereof the following:
"2. Title; Capacity. The Employee shall serve as Senior Vice President or in such other position as the Company
or its Board of Directors (the "Board") may determine from time to time. The Employee shall be based at the
Company's principal offices in New Jersey, unless otherwise agreed by the parties. The Employee shall be
subject to the supervision of, and shall have such authority as is delegated to him by Clive Meanwell (or if Dr.
Meanwell shall have ceased to serve as Chief Executive Officer or Chairman of the Company, the Board or such
officer of the Company as may be designated by the Board).
The Employee hereby accepts such employment on a full-time basis