SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE 13D

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT

TO RULE 13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO

RULE 13d-2(a)

(Amendment No. 5)*

CPEX Pharmaceuticals, Inc.

(Name of Issuer)

Common Stock, par value $0.01 per share

(Title of Class of Securities)

12620N104

(CUSIP Number)

The Mangrove Partners Fund, L.P.

10 East 53rd Street, 31st Floor

New York, New York 10022

Attention: Nathaniel August

Tel: 646.450.0418

(Name, Address and Telephone Number of Person

Authorized to Receive Notices and Communications)

Copies to:

John T. O’Connor

Sadis & Goldberg LLP

551 Fifth Avenue, 21st Floor

New York, New York 10176

Tel: 212.573.8029

March 21, 2011

(Date of Event Which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following box o.

Note. Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 13d-7(b) for other parties to whom copies are to be sent.

* The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes.)

Page 1 of 7 pages

CUSIP No.: 12620N104

NAME OF REPORTING PERSON

1.	S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

	The Mangrove Partners Fund, L.P.

2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
	(a) x
	(b) ¨

3	SEC USE ONLY

4	SOURCE OF FUNDS

	WC, OO

5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e) ¨

6.	CITIZENSHIP OR PLACE OF ORGANIZATION

	Delaware

NUMBER OF	7	SOLE VOTING POWER - 0
SHARES
BENEFICIALLY	8	SHARED VOTING POWER - 149,373
OWNED BY
EACH	9	SOLE DISPOSITIVE POWER - 0
REPORTING
PERSON WITH	10	SHARED DISPOSITIVE POWER - 149,373

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	149,373

12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES ¨

13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

	5.7%*

14	TYPE OF REPORTING PERSON

	PN

* The ownership percentage is calculated based on 2,616,936 shares of Common Stock outstanding as of January 31, 2011, as reported in the Issuer’s Definitive Proxy Statement on Schedule 14A, as filed with the Securities and Exchange Commission on February 4, 2011.

Page 2 of 7 pages

CUSIP No.: 12620N104

1	NAME OF REPORTING PERSON
	S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

	Mangrove Partners

2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
	(a) x
	(b) ¨

3	SEC USE ONLY

4	SOURCE OF FUNDS

	AF

5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e) ¨

6	CITIZENSHIP OR PLACE OF ORGANIZATION

	Cayman Islands

NUMBER OF	7	SOLE VOTING POWER - 0
SHARES
BENEFICIALLY	8	SHARED VOTING POWER - 149,373
OWNED BY
EACH	9	SOLE DISPOSITIVE POWER - 0
REPORTING
PERSON WITH	10	SHARED DISPOSITIVE POWER - 149,373

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	149,373

12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES ¨

13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

	5.7%*

14	TYPE OF REPORTING PERSON

	OO

Page 3 of 7 pages

CUSIP No.: 12620N104

1	NAME OF REPORTING PERSON
	S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

	Mangrove Capital

2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
	(a) x
	(b) ¨

3	SEC USE ONLY

4	SOURCE OF FUNDS

	AF

5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e) ¨

6	CITIZENSHIP OR PLACE OF ORGANIZATION

	Cayman Islands

NUMBER OF	7	SOLE VOTING POWER - 0
SHARES
BENEFICIALLY	8	SHARED VOTING POWER - 149,373
OWNED BY
EACH	9	SOLE DISPOSITIVE POWER - 0
REPORTING
PERSON WITH	10	SHARED DISPOSITIVE POWER - 149,373

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	149,373

12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES o

13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

	5.7%*

14	TYPE OF REPORTING PERSON

	OO

Page 4 of 7 pages

CUSIP No.: 12620N104

1	NAME OF REPORTING PERSON
	S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

	Nathaniel August

2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
	(a) x
	(b) ¨

3	SEC USE ONLY

4	SOURCE OF FUNDS

	AF

5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e) ¨

6	CITIZENSHIP OR PLACE OF ORGANIZATION

	Cayman Islands

NUMBER OF	7	SOLE VOTING POWER - 0
SHARES
BENEFICIALLY	8	SHARED VOTING POWER - 149,373
OWNED BY
EACH	9	SOLE DISPOSITIVE POWER - 0
REPORTING
PERSON WITH	10	SHARED DISPOSITIVE POWER - 149,373

11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	149,373

12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES o

13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

	5.7%*

14	TYPE OF REPORTING PERSON

	IN

Page 5 of 7 pages

Explanatory Note

This Amendment No. 5 to Schedule 13D (this “Amendment No. 5”) is being filed with respect to the beneficial ownership of common stock, par value $0.01 per share (the “Common Stock”), of CPEX Pharmaceuticals, Inc., a Delaware corporation (the “Issuer” or the “Company”). This Amendment No. 5 supplements Items 4 and 7 of the Schedule 13D (as amended) originally filed on January 31, 2011.

ITEM 4.

Purpose of Transaction.

On March 21, 2011, Mangrove Partners issued a press release expressing its disappointment in the Issuer’s board of directors failing to seriously consider the dividend recapitalization proposed by Mangrove Partners. A copy of the March 21, 2011 press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference. On March 22, 2011, Mangrove Partners issued a press release questioning the Issuer’s desperate plea to stockholders asking them to support a merger that will pay the Issuer’s management over $7 million. A copy of the March 22, 2011 press release is attached hereto as Exhibit 99.2 and is incorporated herein by reference. The descriptions herein of the March 21, 2011 and March 22, 2011 press releases are qualified in their entirety by reference to such press releases.

ITEM 7.

Material to be Filed as Exhibits.

Exhibit No.

Document

99.1

Press Release, dated March 21, 2011

99.2

Press Release, dated March 22, 2011

Page 6 of 7 pages

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: March 22, 2011

	THE MANGROVE PARTNERS FUND, L.P.
	MANGROVE PARTNERS
	MANGROVE CAPITAL

	By:	/s/ Nathaniel August
	Nathaniel August, for himself, as Director of Mangrove Capital (for itself and The Mangrove Partners Fund, L.P.) and as a Director of Mangrove Partners

Page 7 of 7 pages

EXHIBIT INDEX

Exhibit No.

Document

99.1	Press Release, dated March 21, 2011

99.2	Press Release, dated March 22, 2011

CPEX Pharmaceuticals, Inc. SC 13D/A