DIFICID® (fidaxomicin) Tablets Approved in Australia

             DIFICID® (fidaxomicin) Tablets Approved in Australia

Specialised Therapeutics Australia to Launch DIFICID May 14, 2013

PR Newswire

JERSEY CITY, N.J., April 26, 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.

(Logo: http://photos.prnewswire.com/prnh/20090413/LA97352LOGO)

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 byC. difficilebacteria, which produce toxins that
cause inflammation of the colon, severe diarrhea and, in the most serious
cases, death.Clostridium difficile-associated diarrheais the most common
symptom of CDI. Patients typically develop CDI from the use of broad-spectrum
antibiotics that disrupt normal gastrointestinal (gut) flora, possibly
allowingC. difficilebacteria 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.

Contacts
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.

Website: http://www.optimerpharma.com