Optimer Pharmaceuticals and AstraZeneca Collaborate to Commercialize Fidaxomicin for Clostridium Difficile Infection in Latin

     Optimer Pharmaceuticals and AstraZeneca Collaborate to Commercialize
       Fidaxomicin for Clostridium Difficile Infection in Latin America

PR Newswire

JERSEY CITY, N.J., Dec. 3, 2012

JERSEY CITY, N.J., Dec. 3, 2012 /PRNewswire/ -- Optimer Pharmaceuticals, Inc.
(NASDAQ: OPTR) announced today the execution of an exclusive agreement with
AstraZeneca to commercialize fidaxomicin tablets for the treatment of
Clostridium difficile Infection (CDI) in South America, including Brazil,
Central America, Mexico and the Caribbean.

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

Under the terms of the agreement AstraZeneca is responsible for the
commercialization of fidaxomicin inthe territory covered by the collaboration
and Optimer is entitled to receive an up-front payment of $1 million, up to $3
million in milestone payments upon first commercial sale in certain countries,
and up to $19 million in other milestone payments contingent on the
achievement of sales-related targets for fidaxomicin in the territory. Optimer
is further entitled to receive payments from AstraZeneca that provide a return
resulting in a double digit percent of net sales in the territory under a
fidaxomicin supply agreement.

"C. difficile infection is a global problem and this collaboration further
advances our plans to make fidaxomicin available to patients in need
globally," said Pedro Lichtinger, President and Chief Executive Officer of
Optimer. "AstraZeneca has the infrastructure and expertise to commercialize
fidaxomicin in the diverse range of countries that make up Central and South
America, and they will be a strong partner moving forward."

Rich Fante, President, AstraZeneca US and Regional Vice President, Americas,
commented on the deal: "We are pleased to partner with Optimer to pursue the
regulatory approval and commercialization of fidaxomicin in Latin America.
This product is a good fit with our hospital portfolio and we look forward to
the opportunity to provide a new treatment option to patients suffering from
this debilitating and sometimes fatal infection."

Fidaxomicin is approved by the U.S. Food and Drug Administration (FDA) for the
treatment of Clostridium difficile-associated diarrhea (CDAD) in adults 18
years of age or older in the United States under the trade name DIFICID®. It
is also approved and marketed in Canada by Optimer for the treatment of
Clostridium difficile infection. In addition, the European Commission granted
Marketing Authorization to fidaxomicin for the treatment of adults with
Clostridium difficile infection under the trade name DIFICLIR™.

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 diarrhea (CDAD) 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 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 forClostridium
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 or
to any of the excipients in the formulation. DIFICID should not be used for
systemic infections. Only use DIFICID for infection proven or strongly
suspected to be caused byC. difficile. Prescribing DIFICID in the absence of
a proven or strongly suspectedC. difficileinfection is unlikely to provide
benefit to the patient and increases the risk of the development of drug
resistant bacteria. The most common adverse reactions are nausea (11%),
vomiting (7%), abdominal pain (6%), gastrointestinal hemorrhage (4%), anemia
(2%) and neutropenia (2%).

AboutOptimer 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, anFDA-approved macrolide antibacterial drug for the treatment
ofClostridium difficile-associated diarrhea (CDAD) 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 theEuropean
Unionwhere 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 whereC. difficilehas
emerged as a serious health problem, includingAsia. Additional information
can be found athttp://www.optimerpharma.com.

About AstraZeneca
AstraZeneca is a global, innovation-driven biopharmaceutical business with a
primary focus on the discovery, development and commercialisation of
prescription medicines for gastrointestinal, cardiovascular, neuroscience,
respiratory and inflammation, oncology and infectious disease. AstraZeneca
operates in over 100 countries and its innovative medicines are used by
millions of patients worldwide. For more information please visit:

Forward-Looking Statements
Statements included in this release that are not a description of historical
facts are forward-looking statements, including without limitation statements
related to the potential availability of fidaxomicin to patients, the
potential benefits of the agreement with AstraZeneca, Optimer's potential
receipt of milestone and other payments under the agreement with AstraZeneca,
and plans to commercialize fidaxomicin globally. Words such as "believes,"
"would," "anticipates," "plans," "expects," "may," "intend," "will," 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. Actual
results may differ materially from those set forth in this release due to the
risks and uncertainties inherent in AstraZeneca and Optimer's businesses
including, without limitation, risks relating to: whether regulatory
authorities will review or approve applications to market fidaxomicin, the
implementation and continuation of the AstraZeneca license agreement, each
party's performance of its respective obligations under the license agreement,
AstraZeneca's ability to successfully commercialize fidaxomicin in the
licensed territory, whether fidaxomicin will receive reimbursement from
government authorities and other healthcare payors, whether healthcare
professionals will prescribe fidaxomicin, the development of alternative
treatments for or means of preventing CDI and other risks detailed in
Optimer's filings with theU.S. Securities and Exchange Commission.

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

OPTIMER and DIFICID are trademarks ofOptimer Pharmaceuticals, Inc.All other
trademarks are the property of their respective owners.

SOURCE Optimer Pharmaceuticals, Inc.

Website: http://www.optimerpharma.com
Website: http://www.astrazeneca.com
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