8-K

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT
Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): March 20, 2008

Penwest Pharmaceuticals Co.

(Exact Name of Registrant as Specified in Charter)

Washington	000-23467	91-1513032
(State or Other Juris- diction of Incorporation	(Commission File Number)	(IRS Employer Identification No.)

39 Old Ridgebury Road, Suite 11 Danbury, Connecticut	06810-5120 (Zip Code)
(Address of Principal Executive Offices)

Registrant’s telephone number, including area code: (877) 736-9378

n/a

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

o Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

TABLE OF CONTENTS

Ex-4.1 Amendment No.2 to Rights Agreement

Item 1.01. Entry into a Material Definitive Agreement.

     On March 20, 2008, the Company entered into an amendment (the “Amendment”) to the Rights Agreement (the “Rights Agreement”), dated as of July 27, 1998, between the Company and Mellon Investor Services LLC, as Rights Agent, as previously amended by Amendment No. 1 thereto. The Amendment modifies the definition of Exempted Person under the Rights Agreement to provide that Perceptive Life Sciences Master Fund Ltd., together with its affiliates and associates (“Perceptive”), will be an Exempted Person under the Rights Agreement until the earlier of the date on which Perceptive beneficially owns more than 21.9% of the outstanding Common Stock or such date when Perceptive beneficially owns less than 10% of the outstanding Common Stock, at which time Perceptive shall cease to be an Exempted Person. Prior to the Amendment, the Rights Agreement provided that the maximum percentage that Perceptive could own as an Exempted Person was 19.9% of the outstanding Common Stock.

     The Amendment is attached to this Current Report on Form 8-K as Exhibit 4.1.

SIGNATURE

     Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	PENWEST PHARMACEUTICALS CO.
Date: March 20, 2008	By:	/s/ Benjamin L. Palleiko
		Benjamin L. Palleiko Senior Vice President, Corporate Development and Chief Financial Officer

EXHIBIT INDEX

Exhibit No.	Description
4.1	Amendment No. 2 to Rights Agreement, dated as of March 20, 2008, between the Registrant and Mellon Investor Services LLC.

EX-4.1

Exhibit 4.1

AMENDMENT NO. 2
TO
RIGHTS AGREEMENT

     This AMENDMENT NO. 2 TO RIGHTS AGREEMENT (the “Amendment”) is entered into as of March 20, 2008, between Penwest Pharmaceuticals Co., a Washington corporation (the “Company”), and Mellon Investor Services LLC, a New Jersey limited liability company, as Rights Agent (the “Rights Agent”). Capitalized terms not otherwise defined herein shall have the meanings given them in the Rights Agreement dated as of July 27, 1998, as amended by Amendment No. 1 thereto (the “Rights Agreement”), between the parties hereto.

RECITALS

     WHEREAS, the Board has determined that it is in the best interest of the Company to amend the Rights Agreement to modify the definition of Exempted Person as provided for in this Amendment;

     WHEREAS, Section 27 of the Rights Agreement provides that, for so long as the Rights (as defined in the Rights Agreement) are then redeemable, the Company may, in its sole and absolute discretion, and the Rights Agent shall, if the Company so directs, supplement or amend any provision of the Rights Agreement in any respect without the approval of any holders of the Rights and, as of the date of this Amendment, the Rights issued pursuant to the Rights Agreement are currently redeemable; and

     WHEREAS, the Company has determined that the Rights Agreement be amended in accordance with Section 27 of the Rights Agreement, as set forth herein, and the Rights Agent is hereby directed to join in the amendment to the Rights Agreement as set forth herein.

AGREEMENT

     NOW THEREFORE, the parties hereto, intending to be legally bound, hereby agree as follows:

1. Section 1(n) of the Rights Agreement is hereby amended to read in its entirety as follows:

“(n) “Exempted Person” shall mean Perceptive Life Sciences Master Fund Ltd., together with its Affiliates and Associates (“Perceptive”), until the earlier of (i) the date on which Perceptive, directly or indirectly, becomes the Beneficial Owner of more than 21.9% of the shares of Common Stock then outstanding or (ii) the date on which Perceptive becomes the holder of less than 10% of the shares of Common Stock then outstanding, at which time Perceptive immediately shall cease to be an Exempted Person.”

2. Except as amended hereby, the Rights Agreement shall remain unchanged and shall remain in full force and effect.

3. This Amendment may be executed in any number of counterparts, each of which shall be an original, but all of which together shall constitute one instrument.

4. This Amendment shall be deemed to be a contract made under the laws of the State of Washington and for all purposes shall be governed by and construed in accordance with the laws of the State of Washington applicable to contracts made and to be performed entirely within the State of Washington; provided, however, that all rights, duties and obligations of the Rights Agent shall be governed by and construed in accordance with the laws of the State of New York applicable to contracts made and to be performed entirely within such state.

[remainder of page intentionally left blank]

     IN WITNESS WHEREOF, the parties have caused this Amendment to be executed by their respective duly authorized representatives as of the date first above written.

PENWEST PHARMACEUTICALS CO.

By:	/s/ Benjamin L. Palleiko
Name:	Benjamin L. Palleiko
Title:	Chief Financial Officer
MELLON INVESTORS SERVICES LLC,
as Rights Agent
By:	/s/ John Boryczki
Name:	John Boryczki
Title: