Penwest Pharmaceuticals (PPCO) 10-Q 2008 Q3 Quarterly report

Exhibit 32.2

CERTIFICATION OF THE PRINCIPAL FINANCIAL OFFICER PURSUANT TO RULE 13a-14(b) OF
THE SECURITIES EXCHANGE ACT OF 1934 AND 18 U.S.C. SECTION 1350

     In connection with the Quarterly Report on Form 10-Q of Penwest Pharmaceuticals Co. (the “Company”) for the period ended September 30, 2008 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), the undersigned, Benjamin L. Palleiko, Senior Vice President, Corporate Development and Chief Financial Officer, hereby certifies, 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; and

     (2) The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: November 6, 2008	/s/ Benjamin L. Palleiko
	Benjamin L. Palleiko
	Senior Vice President, Corporate Development and Chief Financial Officer