UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

~~Washington~~WASHINGTON, D.C. 20549

__________

FORM 8-K

__________

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

~~Securities~~Date ~~Exchange~~of ~~Act~~Report (Date of ~~1934~~Earliest Event Reported): September 24, 2010 (September 24, 2010)

~~Date of Report (Date of earliest event reported): September 17, 2010~~ __________

Penwest Pharmaceuticals Co.

(Exact name of registrant as specified in its charter)

Washington		001-34267		91-1513032
(State or other jurisdiction of incorporation)		(Commission File Number)		(IRS Employer Identification Number)

__________

2981 Route 22, Suite 2

Washington	001-34267	91-1513032
(State or other jurisdiction of incorporation)	(Commission File Number)	(I.R.S. Employer Identification No.)

Patterson, New York

2981 Route 22, Suite 2, Patterson, New York	12563
(Address of principal executive offices)	(Zip Code)

~~(Address~~Registrant’s oftelephone ~~principal~~number, ~~executive~~including ~~offices~~area code (877) 736-9378

~~Registrant’s~~Not ~~telephone number, including area code:~~ Applicable

~~(877-736-9378)~~Former name or former address, if changed since last report

~~(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:

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

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

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

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

~~ITEM~~Item 53.01. ~~CHANGE~~Notice INof ~~CONTROL~~Delisting OFor ~~REGISTRANT.~~Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing

On September 17 30, 2010, West Acquisition Corp., a Delaware corporation (“Purchaser”), and an indirect wholly owned subsidiary of Endo Pharmaceuticals Holdings Inc., a Delaware corporation (“Parent”), completed its tender offer (the “Offer”) for all outstanding shares of common stock, par value $0.001 per share (including shares of common stock issuable upon the conditional exercise of options to purchase shares of common stock and warrants to acquire shares of common stock, each option and warrant having an exercise price of less than $5.00 per share, collectively, the “Shares”), of Penwest Pharmaceuticals Co., ~~a Washington corporation~~ (the “Company”), atnotified aThe ~~price~~NASDAQ ofStock ~~$5.00~~Market ~~per~~that ~~Share,~~it ~~net~~was tonot ~~the seller~~ in ~~cash,~~compliance ~~without~~with ~~interest~~NASDAQ ~~(the~~Listing ~~“Offer~~Rule ~~Price”~~5605(c), ~~and~~relating ~~less any required withholding taxes, upon the terms and subject~~ to ~~the~~audit ~~conditions~~committee ~~set~~requirements ~~forth~~because in the ~~Offer~~Company tono ~~Purchase,~~longer ~~dated~~has ~~August 20,~~a ~~2010.~~three ~~The~~member ~~Offer~~audit ~~expired~~committee atcomprised ~~12:00~~of ~~midnight,~~independent ~~New York City time, on September 17, 2010~~directors. The Company ~~was~~does ~~advised~~not byintend ~~the~~to ~~depositary~~remedy ~~for the~~its ~~Offer~~non-compliance ~~that,~~with assuch ofrule ~~the~~in ~~expiration~~light of ~~the~~its ~~Offer,~~pending amerger ~~total~~with ofan ~~approximately~~indirect ~~30,810,778~~wholly ~~Shares~~owned ~~were~~subsidiary ~~validly~~of ~~tendered~~Endo ~~and~~Pharmaceuticals ~~not~~Holdings ~~withdrawn~~Inc. (~~including 858,109 Shares delivered through notices of guaranteed delivery~~“Endo’), ~~representing~~which ~~approximately~~is ~~82.80%~~expected of the Shares outstanding. On September 20, 2010, Parent announced that Purchaser had accepted for payment, in accordance with the terms of the Offer, all Shares that were validly tendered and not withdrawn prior to ~~the~~close ~~expiration of the Offer. On that same day, Purchaser paid $149,340,488~~ in ~~aggregate~~early ~~consideration~~November ~~for the Shares tendered to the depositary~~2010. "

~~The $149,340,488~~Item in8.01. ~~consideration~~Other payable to holders of Shares tendered during the offer period has been, and any cash payable for Shares to be converted into the right to receive the Offer Price upon the merger of Purchaser with and into the Company pursuant to the Agreement and Plan of Merger, dated as of August 9, 2010, by and among Parent, Purchaser and the Company (the “Merger Agreement”), whereby the Company will become an indirect wholly owned subsidiary of Parent (the “Merger”) will be, provided by cash on hand at Parent and its subsidiariesEvents.

~~The~~On ~~other~~September ~~information~~30, ~~required~~2010, ~~by Item 5.01(~~the Company, issued a) ofpress ~~Form~~release ~~8-K~~announcing isthat ~~contained~~it inwill ~~(i) the~~hold ~~Company’s~~a ~~Solicitation/Recommendation~~special onmeeting ~~Schedule~~of ~~14D-9~~its ~~originally~~shareholders ~~filed~~at by10:00 ~~the~~a.m., ~~Company~~local ~~with~~time, ~~the~~on ~~Securities~~Thursday, ~~and~~November ~~Exchange~~4, ~~Commission~~2010 (at the ~~“SEC”)~~offices onof ~~August 20~~Skadden, ~~2010~~Arps, ~~(the “Schedule~~Slate, ~~14D-9”)~~Meagher & Flom LLP, ~~which~~Four isTimes ~~included~~Square, asNew ~~Exhibit~~York, ~~20.1~~NY 10036, to ~~this~~vote ~~report,~~on ~~and~~the ~~(ii)~~ proposal to approve the ~~Tender~~merger ~~Offer~~of ~~Statement~~West onAcquisition ~~Schedule~~Corp. TOa ~~originally~~Delaware ~~filed~~corporation by(“Merger ~~Purchaser~~Sub”) and ~~Parent~~an ~~with~~indirect ~~the~~wholly ~~SEC~~owned onsubsidiary ~~August 20~~of Endo, ~~2010~~with and into the Company (the “~~Schedule TO~~Merger”), ~~which is~~and ~~included~~to asapprove ~~Exhibit~~the ~~20.2~~Agreement toand ~~this~~Plan ~~report~~of Merger, ~~and~~dated ~~such~~as ~~information~~of isAugust ~~incorporated~~9, ~~herein~~2010, by ~~reference.~~and among the

Company, Merger Sub and Endo (“Merger Agreement”). The ~~foregoing description~~Company's shareholders of ~~certain~~record ~~provisions~~as of the ~~Merger~~close ~~Agreement~~of isbusiness ~~qualified~~on inFriday, ~~its~~September ~~entirety~~24, by2010 ~~reference~~will be entitled to receive notice of and to vote at the special meeting. The approval of the Merger Agreement, ~~which~~requires isthe ~~included~~affirmative asvote ~~Exhibit~~of 20the holders of a majority of all the outstanding shares of common stock, par value $0.3001 per share (“Shares”), of the Company, entitled to ~~this~~vote ~~report~~at the special meeting. Endo and its affiliates own approximately 90.56% of the Shares, and such Shares represent a quorum and sufficient votes to approve the Merger and the Merger Agreement.

~~The~~A ~~information~~copy ~~set~~of ~~forth~~the ~~below~~press inrelease ~~Item 5~~issued by the Company is attached hereto as Exhibit 99.021 and is incorporated herein by reference ~~into this Item 5~~.~~01.~~

ACautionary ~~copy~~Statement ofRegarding ~~the~~Forward-Looking press release issued by Parent on September 20, 2010, announcing Purchaser’s acceptance for payment of Shares validly tendered prior to the expiration of the offering period of the Offer is attached as Exhibit 99.1 hereto and is incorporated by reference herein. Statements

~~ITEM~~This 5report contains “forward-looking statements” that involve significant risks and uncertainties.02 All statements other than statements of historical fact are statements that could be deemed forward-looking statements, including: statements regarding the anticipated timing of filings and approvals relating to the transaction; statements regarding the expected timing of the completion of the transaction; statements regarding the ability to complete the transaction considering the various closing conditions; any statements of expectation or belief; and any statements of assumptions underlying any of the foregoing. ~~DEPARTURE~~Investors OFand ~~DIRECTORS~~security ORholders ~~PRINCIPAL~~are ~~OFFICERS~~cautioned not to place undue reliance on these forward-looking statements. Actual results could differ materially from those currently anticipated due to a number of risks and uncertainties. Risks and uncertainties that could cause results to differ from expectations include: uncertainties as to the timing of the Merger; ~~ELECTION~~the OFeffects ~~DIRECTORS~~of disruption from the transaction making it more difficult to maintain relationships with employees, licensees, other business partners or governmental entities; ~~APPOINTMENT~~other OFbusiness ~~PRINCIPAL~~effects, ~~OFFICERS~~including the effects of industry, economic or political conditions outside of the Company’s control; transaction costs; actual or contingent liabilities; and other risks and uncertainties discussed in documents filed with the Securities and Exchange Commission (the “SEC”) by the Company. Investors and security holders may also obtain free copies of the documents filed with the SEC by the Company at www.penwest.com. The Company does not undertake any obligation to update any forward-looking statements as a result of new information, future developments or otherwise, except as expressly required by law.

InWHERE ~~accordance~~YOU ~~with~~CAN ~~the~~FIND ~~Merger~~MORE Agreement, Messrs. Peter F. Drake, Ph.D., Joseph E. Edelman, John G. Lemkey, David P. Meeker, M.D., Kevin C. Tang, Roderick Wong and Saiid Zarrabian, directors of the Company, resigned from the Board of Directors of the Company (the “Board”), effective as of September 20, 2010, the date that Purchaser accepted for payment and thereby purchased in accordance with the terms of the Offer Shares validly tendered in the Offer and not properly withdrawn. Each resigning director resigned pursuant to the provisions of the Merger Agreement and no director resigned from the Board because of any disagreements with the Company on any matter relating to the Company’s operations, policies or practices. Anne M. VanLent currently remains a Class II director of the Company and is expected to continue as a director until the consummation of the Merger. INFORMATION

In ~~addition~~connection with the proposed merger, ~~effective~~in which Merger Sub shall be merged with and into the Company, the Company filed a preliminary proxy statement with the SEC on September 7, 2010, as ofamended on September 20 24, 2010. When completed, ~~the~~a ~~Board~~definitive ~~appointed~~proxy ~~the~~statement ~~following individuals~~and asa ~~members~~form of proxy will be mailed to the ~~Board:~~shareholders ~~David~~of Pthe Company. ~~Holveck~~BEFORE ~~and~~MAKING ~~Julie~~ANY ~~McHugh~~VOTING asDECISION, ~~Class~~THE ICOMPANY’S ~~directors,~~SHAREHOLDERS ~~Alan~~ARE ~~Levin~~URGED asTO aREAD ~~Class~~THE IIPROXY ~~director,~~STATEMENT ~~and~~REGARDING ~~Ivan~~THE P.MERGER ~~Gergel,~~CAREFULLY ~~M.D.~~AND ~~and~~IN ~~Caroline~~ITS B.ENTIRETY ~~Manogue~~BECAUSE asIT ~~Class~~WILL ~~III~~CONTAIN ~~directors~~IMPORTANT INFORMATION ABOUT THE PROPOSED MERGER. ~~Such~~The ~~persons~~Company’s ~~were~~shareholders ~~designated~~will ~~for~~be ~~appointment~~able ~~as directors~~to obtain, without charge, a copy of the ~~Company~~preliminary byproxy ~~Purchaser~~statement, ~~pursuant~~the todefinitive proxy statement (when available) and other relevant documents filed with the ~~Merger~~SEC ~~Agreement~~from the SEC’s website at http://www.sec.gov. ~~Each~~The ~~such~~Company’s ~~person~~shareholders iswill analso ~~officer~~be ~~and/or~~able ~~director~~to obtain, without charge, a copy of ~~Parent.~~the ~~Information~~preliminary ~~about~~proxy statement, the ~~five~~definitive ~~directors~~proxy ~~designated~~statement ~~for~~(when ~~appointment~~available) byand ~~Purchaser~~other ~~was~~relevant ~~previously~~documents ~~disclosed~~by indirecting ~~the Information~~a ~~Statement~~request ~~comprising~~by ~~Annex~~mail Ior telephone to ~~the~~Penwest ~~Schedule~~Pharmaceuticals ~~14D~~Co., Attn: Corporate Secretary, 2981 Route 22, Suite 2, Patterson, New York 12563, telephone: (877) 736-99378, ~~and~~or isfrom ~~incorporated~~the ~~herein~~Company’s bywebsite, ~~reference~~http://www. penwest.com.

~~The~~PARTICIPANTS ~~foregoing description~~IN ofTHE ~~certain provisions of the Merger Agreement is qualified in its entirety by reference to the Merger Agreement, which is included as Exhibit 20.3 to this report.~~ SOLICITATION

The ~~other~~Company ~~information~~and ~~required~~its bydirectors ~~Item 5~~and officers may be deemed to be participants in the solicitation of proxies from the Company’s shareholders with respect to the Merger.02 Information about the Company’s directors and executive officers and their ownership of ~~Form~~the ~~8-K~~Company’s common stock is ~~contained~~set forth in the ~~Schedule~~Company's ~~14D-9~~preliminary proxy statement filed with the SEC on September 7, ~~including~~2010, as amended on September 24, 2010. Shareholders may obtain additional information regarding the ~~Information~~interests ~~Statement comprising~~of ~~Annex~~the ICompany ~~thereto~~and its directors and executive officers in the Merger, which ismay ~~included~~be asdifferent ~~Exhibit~~than ~~20.1~~those toof ~~this~~the ~~report~~Company’s shareholders generally, by reading the preliminary proxy statement, the definitive proxy statement (when available) and ~~such~~other ~~information~~relevant isdocuments ~~incorporated~~regarding ~~herein~~the byMerger, ~~reference.~~when filed with the SEC.

~~ITEM~~Item 89.01. ~~OTHER~~Financial ~~EVENTS~~Statements and Exhibits.

On September 20, 2010, Parent issued a press release announcing that Purchaser accepted for payment in accordance with the terms of the Offer all Shares that were validly tendered and not withdrawn prior to expiration of the Offer, and that payment for such Shares would be made promptly, in accordance with the terms of the Offer. A copy of the press release is attached as Exhibit 99.1 hereto and is incorporated by reference herein.

ITEM 9.01. FINANCIAL STATEMENTS AND EXHIBITS.

(d)

Exhibits.

20.1		Solicitation/Recommendation Statement on Schedule 14D-9 of Penwest Pharmaceuticals Co. (incorporated by reference in its entirety as originally filed with the SEC on August 20, 2010).
Exhibit Number		Description
20.2		Tender Offer Statement on Schedule TO of West Acquisition Corp. and Endo Pharmaceuticals Holdings Inc. (incorporated by reference in its entirety as originally filed with the SEC on August 20, 2010).
99.1		Press Release issued by Penwest Pharmaceuticals Co. on September 30, 2010, announcing the record date and the date of the special meeting of shareholders.
20.3		Agreement and Plan of Merger, dated as of August 9, 2010, by and among Endo Pharmaceuticals Holdings Inc., West Acquisition Corp. and Penwest Pharmaceuticals Co. (incorporated by reference to Exhibit 2.1 to the Current Report on Form 8-K filed by Endo Pharmaceuticals Holdings Inc. with the Securities Exchange Commission on August 12, 2010).
99.1		Press Release issued by Endo Pharmaceuticals Holdings Inc. on September 20, 2010 (incorporated by reference to Exhibit 99.1 to the Current Report on Form 8-K filed by Endo Pharmaceuticals Holdings Inc. with the Securities Exchange Commission on September 20, 2010).

~~SIGNATURE~~ SIGNATURES

~~After~~Pursuant ~~due~~to ~~inquiry~~the ~~and~~requirements toof the ~~best~~Securities Exchange Act of my1934, ~~knowledge~~the ~~and~~Registrant ~~belief,~~has Iduly ~~certify~~caused ~~that~~this ~~the~~report ~~information~~to ~~set~~be ~~forth~~signed inon ~~this~~its ~~statement~~behalf isby ~~true~~the undersigned, ~~complete~~ ~~and~~hereunto ~~correct.~~duly authorized.

~~Penwest~~PENWEST ~~Pharmaceuticals~~PHARMACEUTICALS CoCO. (Registrant) By: /s/ ~~JENNIFER~~Jennifer L. ~~GOOD~~Good Name: Jennifer L. Good Title: President and Chief Executive Officer

Dated: September 2030, 2010

~~EXHIBIT~~ INDEX TO EXHIBITS

20.1		Solicitation/Recommendation Statement on Schedule 14D-9 of Penwest Pharmaceuticals Co. (incorporated by reference in its entirety as originally filed with the SEC on August 20, 2010).
Exhibit Number		Description
20.2		Tender Offer Statement on Schedule TO of West Acquisition Corp. and Endo Pharmaceuticals Holdings Inc. (incorporated by reference in its entirety as originally filed with the SEC on August 20, 2010).
99.1		Press Release issued by Penwest Pharmaceuticals Co. on September 30, 2010, announcing the record date and the date of the special meeting of shareholders.
20.3		Agreement and Plan of Merger, dated as of August 9, 2010, by and among Endo Pharmaceuticals Holdings Inc., West Acquisition Corp. and Penwest Pharmaceuticals Co. (incorporated by reference to Exhibit 2.1 to the Current Report on Form 8-K filed by Endo Pharmaceuticals Holdings Inc. with the Securities Exchange Commission on August 12, 2010).
99.1		Press Release issued by Endo Pharmaceuticals Holdings Inc. on September 20, 2010 (incorporated by reference to Exhibit 99.1 to the Current Report on Form 8-K filed by Endo Pharmaceuticals Holdings Inc. with the Securities Exchange Commission on September 20, 2010).

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