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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

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

OPTIMER PHARMACEUTICALS, INC.

(Name of Issuer)

Common Stock, par value $0.001 per share

(Title of Class of Securities)

68401H104

(CUSIP Number)

October 3, 2007

(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.		68401H104


1	NAMES OF REPORTING PERSONS Par Pharmaceutical, Inc.


2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
	(a) o
	(b) o

3	SEC USE ONLY



4	CITIZENSHIP OR PLACE OF ORGANIZATION

	USA

		5	SOLE VOTING POWER

NUMBER OF			0

SHARES		6	SHARED VOTING POWER
BENEFICIALLY
OWNED BY			0

EACH		7	SOLE DISPOSITIVE POWER
REPORTING
PERSON			0

WITH:		8	SHARED DISPOSITIVE POWER

			0

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	0

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)

	0.00%

12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	CO

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Item 1.

(a)

Name of Issuer:

Optimer Pharmaceuticals, Inc. (the “Company”)

(b)

Address of Issuer’s Principal Executive Offices:

10110 Sorrento Valley Road, Suite C
San Diego, California 92121

Item 2.

(a)

Name of Person Filing:

This report is being filed by Par Pharmaceutical, Inc., a Delaware corporation (“Par”).

(b)

Address of Principal Business Office:

300 Tice Boulevard
Woodcliff Lake, NJ, 07677

(c)

Citizenship:

Delaware corporation

(d)

Title of Class of Securities:

Common stock, $0.001 par value (the “Common Stock”)

(e)

CUSIP Number:

69888P106

Item 3. If this statement is filed pursuant to Rule 13d-1(b) or 13d-2(b) or (c), check the status of the person filing:


(a)	o	Broker of dealer registered under section 15 of the Act;
(b)	o	Bank as defined in section 3(a)(6) of the Act;

(c)	o	Insurance company as defined in section 3(a)(19) of the Act;
(d)	o	Investment company registered under section 8 of the Investment Company Act of 1940;

(e)	o	An investment adviser in accordance with §240.13d-1(b)(l)(ii)(E);
(f)	o	An employee benefit plan or endowment fund in accordance with §240.13d-1(b)(1)(ii)(F);

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(g)	o	A parent holding company or control person in accordance with §240.13d-1(b)(1)(ii)(G);
(h)	o	A savings association as defined in Section 3(b) of the Federal Deposit Insurance Act;
(i)	o	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940;
(j)	o	Group, in accordance with §240.13d- 1((b)(l)(ii)(J)


Item 4.		Ownership:

(a)

Amount beneficially owned:

0 shares of Common Stock.

(b)

Percent of class:

0.00%

(c)

Number of shares as to which the person has:

(i)

Sole power to vote or to direct the vote:

(ii)

Shared power to vote or to direct the vote:

(iii)

Sole power to dispose or to direct the disposition of:

(iv)

Shared power to dispose or to direct the disposition of:


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 person has ceased to be the beneficial owner of more than 5 percent of the class of securities, check the following [x].


Item 6.		Ownership of More than Five Percent on Behalf of Another Person:

Not Applicable.

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Item 7.		Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company or Control Person:

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.		Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

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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.

Date: October 16, 2007


	Par Pharmaceutical, Inc.
	By:	/s/ Thomas J. Haughey
	Name:	Thomas J. Haughey
	Title:	Executive Vice President and General Counsel

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