SC 13G

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934
(Amendment No.      )*

Somaxon Pharmaceuticals, Inc.

(Name of Issuer)

Common Stock, par value $0.0001 per share

(Title of Class of Securities)

834453 10 2

(CUSIP Number)

July 8, 2009

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

     o Rule 13d-1(b)

     þ Rule 13d-1(c)

     o Rule 13d-1(d)

* 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 the disclosures provided in a prior cover page.

The information required in 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 (“Act”) 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).

CUSIP No. 834453 10 2 

1	NAMES OF REPORTING PERSONS Prospect Venture Partners III, L.P.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a)   o
	(b)   þ (1)
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION
	Delaware, United States of America
		5	SOLE VOTING POWER
NUMBER OF			0 shares
SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			1,717,168 shares of Common Stock (2)
EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			0 shares
WITH:		8	SHARED DISPOSITIVE POWER
			1,717,168 shares of Common Stock (2)
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
	1,717,168 shares of Common Stock (2)
10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)
	o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)
	7.17%(3)
12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)
	PN

(1) This Schedule 13G is filed by Prospect Venture Partners III, L.P., a Delaware limited partnership (“PVP III”) and Prospect Management Co. III, L.L.C., a Delaware limited liability company (“PMC III,” together with PVP III, the “Reporting Persons”). The Reporting Persons expressly disclaim status as a “group” for purposes of this Schedule 13G.

(2) Includes (i) 1,291,637 shares of the Issuer’s Common Stock held by PVP III; and (ii) 425,531 shares of the Issuer’s Common Stock issuable pursuant to a warrant to purchase common stock held by PVP III. PMC III serves as the sole general partner of PVP III, and owns no securities of the Issuer directly. The information with respect to the ownership of the Common Stock by the Reporting Persons filing this statement on Schedule 13G is provided as of July 8, 2009.

(3) This percentage is calculated based upon 23,536,622 shares of the Common Stock outstanding as of July 8, 2009 (calculated on the basis of (i) 18,430,247 shares available as of May 1, 2009, as set forth in the Issuer’s most recent 10-Q, filed with the Securities and Exchange Commission (the “SEC”) on May 8, 2009 and (ii) 5,106,375 shares issued in connection with a private placement of Common Stock, as disclosed in the Form 8-K filed by the Issuer with the SEC on July 8, 2009.

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CUSIP No. 834453 10 2 

1	NAMES OF REPORTING PERSONS Prospect Management Co. III, L.L.C.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a)   o
	(b)   þ (1)
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION
	Delaware, United States of America
		5	SOLE VOTING POWER
NUMBER OF			0 shares
SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			1,717,168 shares of Common Stock (2)
EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			0 shares
WITH:		8	SHARED DISPOSITIVE POWER
			1,717,168 shares of Common Stock (2)
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
	1,717,168 shares of Common Stock (2)
10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)
	o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)
	7.17%(3)
12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)
	OO

(1) This Schedule 13G is filed by the Reporting Persons. The Reporting Persons expressly disclaim status as a “group” for purposes of this Schedule 13G.

(2) Includes (i) 1,291,637 shares of the Issuer’s Common Stock held by PVP III; and (ii) 425,531 shares of the Issuer’s Common Stock issuable pursuant to a warrant to purchase common stock held by PVP III. PMC III serves as the sole general partner of PVP III, and owns no securities of the Issuer directly. The information with respect to the ownership of the Common Stock by the Reporting Persons filing this statement on Schedule 13G is provided as of July 8, 2009.

(3) This percentage is calculated based upon 23,536,622 shares of the Common Stock outstanding as of July 8, 2009 (calculated on the basis of (i) 18,430,247 shares available as of May 1, 2009, as set forth in the Issuer’s most recent 10-Q, filed with the SEC on May 8, 2009 and (ii) 5,106,375 shares issued in connection with a private placement of Common Stock, as disclosed in the Form 8-K filed by the Issuer with the SEC on July 8, 2009.

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Introductory Note: This Statement on Schedule 13G is filed on behalf of the Reporting Persons, in respect of shares of Common Stock, par value $0.0001 per share (“Common Stock”), of Somaxon Pharmaceuticals, Inc. (the “Issuer”).

Item 1

(a)	Name of Issuer: Somaxon Pharmaceuticals, Inc.
(b)	Address of Issuer’s Principal Executive Offices:
	420 Stevens Avenue, Suite 210 Solana Beach, California 92075

Item 2

(a) Name of Person(s) Filing:

Prospect Venture Partners III, L.P. (“PVP III”)
Prospect Management Co. III, L.L.C. (“PMC III”)

(b) Address of Principal Business Office:

c/o Prospect Venture Partners
435 Tasso Street, Suite 200
Palo Alto, California 94301

(c) Citizenship:

Entities: PVP III — Delaware, United States of America
PMC III — Delaware, United States of America

(d)	Title of Class of Securities: Common Stock
(e)	CUSIP Number: 834453 10 2

Item 3 Not applicable.

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Item 4 Ownership.

The following information with respect to the ownership of the Common Stock by the Reporting Persons filing this statement on Schedule 13G is provided as of July 8, 2009:

Common Stock

Issuable Upon

Shares of

Exercise of

Common

Common Stock

Shared

Percentage

Reporting

Stock Held

Purchase

Shared Voting

Dispositive

Beneficial

of

Persons

Directly

Warrant

Power (1)

Power (1)

Ownership (1)

Class (1, 3)

PVP III

1,291,637

425,531

1,717,168

1,717,168

1,717,168

7.17

%

PMC III (2)

0

0

1,717,168

1,717,168

1,717,168

7.17

%

(1)	Represents the number of shares of Common Stock currently underlying all Securities held by the Reporting Person.
(2)	PMC III serves as the sole general partner of PVP III and possesses sole power to direct the voting and disposition of the shares owned by PVP III and may be deemed to have indirect beneficial ownership of the shares held by PVP III. PMC III owns no securities of the Issuer directly.
(3)	This percentage is calculated based upon 23,536,622 shares of the Common Stock outstanding as of July 8, 2009 (calculated on the basis of (i) 18,430,247 shares available as of May 1, 2009, as set forth in the Issuer’s most recent 10-Q, filed with the SEC on May 8, 2009 and (ii) 5,106,375 shares issued in connection with a private placement of Common Stock, as disclosed in the Form 8-K filed by the Issuer with the SEC on July 8, 2009

Item 5 Ownership of Five Percent or Less of a Class.

If this statement is being filed to report the fact that as of the date hereof, the Reporting Persons have ceased to be the beneficial owner of more than five percent of the class of securities, check the following: o

Item 6	Ownership of More Than Five Percent on Behalf of Another Person.
	Not applicable.

Item 7	Identification and Classification of the Subsidiary which Acquired the Security Being Reported on by the Parent Holding Company.
	Not applicable.

Item 8	Identification and Classification of Members of the Group.
	Not applicable.

Item 9	Notice of Dissolution of Group.
	Not applicable.

Item 10	Certification.
	Not applicable.

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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: July 16, 2009

PROSPECT VENTURE PARTNERS III, L.P.
By:	Prospect Management Co. III, L.L.C.
Its:	General Partner
/s/ Dave Markland
Dave Markland
Attorney-in-Fact
PROSPECT MANAGEMENT CO. III, L.L.C.
/s/ Dave Markland
Dave Markland
Attorney-in-Fact

Exhibit(s):

99.1: Joint Filing Statement

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EX-99.1

Exhibit 99.1

AGREEMENT

     Pursuant to Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree that only one statement containing the information required by Schedule 13G need be filed with respect to the ownership by each of the undersigned of the shares of Common Stock of Somaxon Pharmaceuticals, Inc.

Dated: July 16, 2009

PROSPECT VENTURE PARTNERS III, L.P.
By:	Prospect Management Co. III, L.L.C.
Its:	General Partner
/s/ Dave Markland
Dave Markland
Attorney-in-Fact
PROSPECT MANAGEMENT CO. III, L.L.C.
/s/ Dave Markland
Dave Markland
Attorney-in-Fact

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