POS EX

As filed with the Securities and Exchange Commission on November 23, 2010

Registration No. 333-169210

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

POST-EFFECTIVE AMENDMENT NO. 1 TO

FORM S-1

REGISTRATION STATEMENT

Under

The Securities Act of 1933

ZOGENIX, INC.

(Exact name of registrant as specified in its charter)

Delaware	2834	20-5300780
(State or other jurisdiction of incorporation or organization)	(Primary Standard Industrial Classification Code Number)	(I.R.S. Employer Identification Number)

12671 High Bluff Drive, Suite 200

San Diego, CA 92130

(858) 259-1165

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Roger L. Hawley

Chief Executive Officer

Zogenix, Inc.

12671 High Bluff Drive, Suite 200

San Diego, CA 92130

(858) 259-1165

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:
Scott N. Wolfe, Esq. Cheston J. Larson, Esq. Matthew T. Bush, Esq. Latham & Watkins LLP 12636 High Bluff Drive, Suite 400 San Diego, CA 92130 (858) 523-5400	Eric S. Haueter, Esq. Heather A. Childress, Esq. Sidley Austin LLP 555 California Street, 20th Floor San Francisco, CA 94104 (415) 772-1200

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box.  ¨

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ¨

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ¨

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  x  333-169210

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer	¨	Accelerated filer	¨
Non-accelerated filer	x  (Do not check if a smaller reporting  company)	Smaller reporting company	¨

This Registration Statement shall become effective upon filing with the Securities and Exchange Commission in accordance with Rule 462(d) under the Securities Act.

EXPLANATORY NOTE

This Post-Effective Amendment No. 1 (the “Amendment”) relates to the Registrant’s Registration Statement on Form S-1, as amended (File No. 333-169210), initially filed by the Registrant on September 3, 2010 and declared effective by the Securities and Exchange Commission on November 22, 2010. The Registrant is filing this Amendment for the sole purpose of replacing Exhibit 5.1 to the Registration Statement. This Amendment does not modify any provision of Part I or Part II of the Registration Statement other than Item 16(a) of Part II as set forth below.

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 16. Exhibits and Financial Statement Schedules

(a) Exhibits

Exhibit Number	Description
5.1	Opinion of Latham & Watkins LLP

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, Zogenix, Inc. has duly caused this Post-Effective Amendment No. 1 to Registration Statement on Form S-1 to be signed on its behalf by the undersigned, thereunto duly authorized, in San Diego, California on the 23rd day of November, 2010.

ZOGENIX, INC.
By:	/S/ ROGER L. HAWLEY
	Roger L. Hawley
	Chief Executive Officer

Pursuant to the requirements of the Securities Act of 1933, as amended, this Post-Effective Amendment No. 1 to Registration Statement on Form S-1 has been signed by the following persons in the capacities and on the dates indicated.

Signature	Title	Date
/S/ ROGER L. HAWLEY     Roger L. Hawley	Chief Executive Officer and Director (Principal Executive Officer)	November 23, 2010
/S/ ANN D. RHOADS     Ann D. Rhoads	Executive Vice President, Chief Financial Officer, Treasurer and Secretary (Principal Financial and Accounting Officer)	November 23, 2010
* Cam L. Garner	Chairman of the Board	November 23, 2010
* James C. Blair, Ph.D.	Director	November 23, 2010
* Louis C. Bock	Director	November 23, 2010
* Stephen J. Farr, Ph.D.	President, Chief Operating Officer and Director	November 23, 2010
* Ken Haas	Director	November 23, 2010
* Erle T. Mast	Director	November 23, 2010
* Arda M. Minocherhomjee, Ph.D.	Director	November 23, 2010
* Kurt C. Wheeler	Director	November 23, 2010

* By:	/S/ ROGER L. HAWLEY
	Roger L. Hawley
	Attorney-in-Fact

EXHIBIT INDEX

Exhibit Number	Description
5.1	Opinion of Latham & Watkins LLP

EX-5.1

Exhibit 5.1

	12636 High Bluff Drive, Suite 400 San Diego, California 92130-2071 Tel: +1.858.523.5400 Fax: +1.858.523.5450 www.lw.com
	FIRM / AFFILIATE OFFICES
	Abu Dhabi Barcelona Beijing Brussels Chicago Doha Dubai Frankfurt Hamburg Hong Kong Houston London Los Angeles Madrid Milan	Moscow Munich New Jersey New York Orange County Paris Riyadh Rome San Diego San Francisco Shanghai Silicon Valley Singapore Tokyo Washington, D.C.
November 23, 2010
Zogenix, Inc. 12671 High Bluff Drive, Suite 200 San Diego, California 92130

File No. 042073-0009

Re: Registration Statement No. 333-169210; 16,100,000 shares of Common Stock, par value $0.001 per share

Ladies and Gentlemen:

We have acted as special counsel to Zogenix, Inc., a Delaware corporation (the “Company”), in connection with the proposed issuance of up to 16,100,000 shares (including up to 2,100,000 shares subject to the underwriters’ over-allotment option) of common stock, $0.001 par value per share (the “Shares”). The Shares are included in a registration statement on Form S-1 under the Securities Act of 1933, as amended (the “Act”), filed with the Securities and Exchange Commission (the “Commission”) on September 3, 2010 (File No. 333-169210), as amended (the “Registration Statement”). The term “Shares” shall include any additional shares of common stock registered by the Company pursuant to Rule 462(b) under the Act in connection with the offering contemplated by the Registration Statement. This opinion is being furnished in connection with the requirements of Item 601(b)(5) of Regulation S-K under the Act, and no opinion is expressed herein as to any matter pertaining to the contents of the Registration Statement or related Prospectus, other than as expressly stated herein with respect to the issue of the Shares.

As such counsel, we have examined such matters of fact and questions of law as we have considered appropriate for purposes of this letter. With your consent, we have relied upon certificates and other assurances of officers of the Company and others as to factual matters without having independently verified such factual matters. We are opining herein as to the General Corporation Law of the State of Delaware and we express no opinion with respect to any other laws.

Subject to the foregoing and the other matters set forth herein, it is our opinion that, as of the date hereof, when the Shares shall have been duly registered on the books of the transfer agent and registrar therefor in the name or on behalf of the purchasers, and have been issued by the Company against payment therefor in the circumstances contemplated by the form of underwriting agreement most recently filed as an exhibit to the Registration Statement, the issue and sale of the Shares will have been duly authorized by all necessary corporate action of the Company, and the Shares will be validly issued, fully paid and nonassessable. In rendering the foregoing opinion, we have assumed that the Company will comply with all applicable notice requirements regarding uncertificated shares provided in the General Corporation Law of the State of Delaware.

This opinion is for your benefit in connection with the Registration Statement and may be relied upon by you and by persons entitled to rely upon it pursuant to the applicable provisions of the Act. We consent to your filing this opinion as an exhibit to the Registration Statement and to the reference to our firm in the Prospectus under the heading “Legal Matters.” In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Act or the rules and regulations of the Commission thereunder.

Very truly yours,

/s/ Latham & Watkins LLP