Optimer Pharmaceuticals Reports Inducement Grants Under NASDAQ Listing Rule 5635(c)(4)

Optimer Pharmaceuticals, Inc. OPTR announced today that on June 30, 2011 the Compensation Committee of its Board of Directors approved the grant of inducement stock options to purchase an aggregate of 342,000 shares of common stock to 73 new employees. Each stock option has an exercise price per share equal to $11.89, the fair market value on the grant date, and vests over four years, with 25% of the shares vesting on the one-year anniversary of the applicable vesting commencement date and 1/48 of the shares vesting monthly thereafter, subject to the new employee's continued service relationship with the Company. Each stock option also has a ten year term and is subject to the terms and conditions of the Company's 2006 Equity Incentive Plan and the stock option agreement pursuant to which the option was granted.