ENCY Encysive Pharmaceuticals (MM)

This Amendment No. 1 (the “Amendment”) amends the Statement on Schedule 13D filed on April 11, 2008 (the “Original Schedule”) by the Reporting Persons (the Original Schedule as amended by this Amendment is referred to as the “Schedule 13D”) and is filed by Pfizer Inc. (“Pfizer”), and its wholly-owned subsidiary, Explorer Acquisition Corp. (“Explorer” or the “Purchaser”), and relates to the common stock, including the associated preferred stock purchase rights (“Common Stock”), $0.005 par value per share, of Encysive Pharmaceuticals Inc., a Delaware corporation (“Encysive” or the “Company”). Unless otherwise indicated, all capitalized terms used herein have the meaning ascribed to them in the Original Schedule.

(a) and (b)   As a result of purchases of Shares pursuant to the Offer, on April 15, 2008, Pfizer and Explorer beneficially own an aggregate 69,076,466 shares (the “Shares”) of Common Stock, representing 85.33% of the outstanding shares of Common Stock (based upon 80,955,060 Shares issued and outstanding as of April 14, 2008, as reported to the Reporting Persons by the transfer agent for the Shares). Pfizer and Explorer each have sole voting and dispositive power of all the Shares by virtue of the fact that Explorer, the record holder of the Shares, is a wholly-owned subsidiary of Pfizer.

(c)    Since the filing of the Original Schedule and through the expiration of the subsequent offering period at 5:00 p.m., New York City time, on April 14, 2008, Explorer purchased the following number of Shares on the following dates at the offer price of $2.35 per Share:

(d)    Except as set forth in this Amendment, none of the Reporting Parties has the right to receive or the power to direct the receipt of dividends from, or the proceeds of the sale of, securities covered by the Schedule 13D.

4