DIFICID® (fidaxomicin) Tablets Approved in Australia

Specialised Therapeutics Australia to Launch DIFICID May 14, 2013

JERSEY CITY, N.J., April 26, 2013 /PRNewswire/ -- Optimer Pharmaceuticals, Inc. (NASDAQ: OPTR) today announced that the Therapeutic Goods Administration, the Australian regulatory body for therapeutic goods such as medicines, has approved DIFICID® (fidaxomicin) tablets for the treatment of confirmed Clostridium difficile infection (CDI) in adults. DIFICID will be available to patients in Australia starting May 14, 2013 from Specialised Therapeutics Australia Pty, Ltd. (STA), which licensed exclusive rights to fidaxomicin in Australia and New Zealand from Optimer. STA is also responsible for registration and commercialization of DIFICID in New Zealand.

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The Australian approval is based on the same two pivotal Phase 3 clinical trials that were sponsored by Optimer to ensure the safety and efficacy of 200 mg twice daily DIFICID (fidaxomicin) tablets compared to 125 mg four times daily oral vancomycin for 10 days in subjects with CDI.

"Clostridium difficile infections represent a burden to patients and a challenge to treating physicians around the globe. An innovative drug like DIFICID is an important option that should be widely available to patients," said Dr. Hank McKinnell, Optimer's CEO and Chairman of the Board. "With the recent approval in Australia, and the earlier approvals in the U.S., Europe and Canada, fidaxomicin is now approved by four regulatory agencies, broadening access to patients in need across the globe."

About CDI
CDI is a significant medical problem in hospitals, long-term care facilities and in the community. CDI is a serious illness resulting from infection of the inner lining of the colon by C. difficile bacteria, which produce toxins that cause inflammation of the colon, severe diarrhea and, in the most serious cases, death. Clostridium difficile-associated diarrhea is the most common symptom of CDI. Patients typically develop CDI from the use of broad-spectrum antibiotics that disrupt normal gastrointestinal (gut) flora, possibly allowing C. difficile bacteria to flourish. Older patients, in particular, are at risk for CDI, potentially because of a weakened immune system or the presence of underlying disease.

About DIFICID® (fidaxomicin) Tablets 
DIFICID is the first macrolide antibacterial drug indicated for Clostridium difficile-associated diarrhea (CDAD) to be approved in over 25 years in the U.S.  It is indicated in the U.S. for the treatment of CDAD in adults 18 years of age or older.  DIFICID is administered in 200 milligram tablets given orally, twice daily.

Important Safety Information for DIFICID 
DIFICID is contraindicated in patients with hypersensitivity to fidaxomicin.  DIFICID should not be used for systemic infections.  Acute hypersensitivity reactions (angioedema, dyspnea, pruritus, and rash) have been reported. In the event of a severe reaction, discontinue DIFICID.  Only use DIFICID for infection proven or strongly suspected to be caused by C. difficile. Prescribing DIFICID in the absence of a proven or strongly suspected C. difficile infection is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria.  The most common adverse reactions reported in clinical trials are nausea (11%), vomiting (7%), abdominal pain (6%), gastrointestinal hemorrhage (4%), anemia (2%), and neutropenia (2%).

Please visit www.DIFICID.com or call 855-DIFICID (343-4243) for full prescribing information for DIFICID.

About Optimer Pharmaceuticals 
Optimer Pharmaceuticals, Inc. is a global biopharmaceutical company focused on developing and commercializing innovative hospital specialty products that have a positive impact on society.  Optimer developed DIFICID® (fidaxomicin) tablets, an FDA-approved macrolide antibacterial drug for the treatment of Clostridium difficile-associated diarrhea in adults 18 years of age and older, and is commercializing DIFICID in the U.S. and Canada.  Optimer also received marketing authorization for fidaxomicin tablets in the European Union where its partner, Astellas Pharma Europe, is commercializing fidaxomicin under the trade name DIFICLIR™.  The Company is exploring marketing authorization in other parts of the world where C. difficile has emerged as a serious health problem. Additional information can be found at http://www.optimerpharma.com.

Forward Looking Statements
Statements included in this press release that are not a description of historical facts are forward-looking statements, including, without limitation, the statements related to the date that DIFICID will be available in Australia.  Words such as "expect," "anticipate," "will," "could," "would," "project," "intend," "plan," "believe," "predict," "estimate," "should," "may," "potential," "continue," "ongoing" or variations of such words and similar expressions are intended to identify forward-looking statements. The inclusion of forward-looking statements should not be regarded as a representation by Optimer that any of its plans will be achieved. These forward-looking statements are based on management's expectations on the date of this release. Actual results may differ materially from those set forth in this release due to the risks and uncertainties inherent in Optimer's business including, without limitation, risks detailed in Optimer's filings with the Securities and Exchange Commission. Forward-looking statements speak only as of the date of this release, and Optimer undertakes no obligation to update or revise these statements, except as may be required by law.

Optimer Pharmaceuticals, Inc.
David Walsey, Vice President, Investor Relations and Corporate Communications
(858) 964-3418

Canale Communications, Inc.
Jason I. Spark, Senior Vice President
(619) 849-6005

SOURCE Optimer Pharmaceuticals, Inc.