EXHIBIT 99.2 CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350, AS ADOPTED PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002 In connection with the Quarterly Report of Texas Biotechnology Corporation (the "Company") on Form 10-Q for the period ending September 30, 2002 (the "Report"), as filed with the Securities and Exchange Commission on the date hereof, I, Stephen L. Mueller, Vice President, Finance & Administration of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that: 1. The Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; and 2. The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company. /s/ STEPHEN L. MUELLER - ---------------------------------------- Stephen L. Mueller Vice President, Finance & Administration November 8, 2002