Hyperion Therapeutics Announces Initiation of THRIVE Study, a Long-Term Registry of Patients With Urea Cycle Disorders

Hyperion Therapeutics Announces Initiation of THRIVE Study, a Long-Term
Registry of Patients With Urea Cycle Disorders

SOUTH SAN FRANCISCO, Calif., Oct. 31, 2013 (GLOBE NEWSWIRE) -- Hyperion
Therapeutics, Inc. (Nasdaq:HPTX) today announced that it has begun enrolling
patients in its THRIVE study, a long term registry of patients with urea cycle
disorders (UCDs) which will capture clinical outcomes and comparative
effectiveness data.

The THRIVE study is a multi-center, prospective, non-interventional study
designed to collect data in up to 500 UCD patients as part of their routine
management. The study will track long-term outcomes, including hyperammonemic
crises, ammonia levels, growth and development, and neurocognitive outcomes.
Eligible patients will be enrolled in the study and followed for up to 10
years with annual interim data reports planned. At the time of enrollment,
retrospective and baseline data will be collected. Data will also be collected
during routine office visits. In addition, the study will capture the
duration, dose, frequency, and route of administration of all current standard
of care treatments, including ammonia-scavenging agents sodium phenylbutyrate,
glycerol phenylbutyrate, or sodium benzoate. THRIVE offers the assistance of a
Central Research Coordinating Office which facilitates participation and
reduces the burden of study procedures on participating sites for all
interested physicians and patients.Interested parties can visit the THRIVE
website (www.thriveregistry.com) or contact thriveregistry@unitedbiosource.com
to be included in the program.

"We are pleased to initiate this disease registry," said Bruce Scharschmidt,
M.D., chief medical officer of Hyperion. "THRIVE meets one of our post
marketing commitments to the FDA and will also contribute importantly to our
understanding of UCDs and their management." "We have worked closely with the
UCD community in designing this registry and are hopeful that it will help
define best practices and potential improvements in management that will
benefit patients both within and potentially outside the United States."

UCD patients lack enzymes or transporters necessary for the conversion of
ammonia to urea and experience heightened levels of ammonia in the
bloodstream. Left untreated, UCDs can result in neurological damage, coma,
and/or death. Approved by the Food and Drug Administration on February 1,
2013, RAVICTI is an oral medication used for the long-term management of high
blood levels of ammonia.In short term clinical studies involving more than 80
UCD patients ages two years and older, RAVICTI was safe and efficacious based
on 24-hour ammonia profiles.In addition in long-term follow up studies,
patients on RAVICTI maintained average fasting ammonia levels below the upper
limit of normal.What makes RAVICTI unique from other ammonia removing
medicines is that the active ingredient is released slowly in the body, mostly
in the small intestine.

About BUPHENYL (sodium phenylbutyrate) Tablets and Powder

BUPHENYL is indicated as adjunctive therapy in the chronic management of
patients with urea cycle disorders involving deficiencies of carbamylphosphate
synthetase (CPS), ornithine transcarbamylase (OTC), or argininosuccinic acid
synthetase (AS). BUPHENYL should not be administered to patients with known
hypersensitivity to sodium phenylbutyrate or any component of this
preparation. The most common adverse reactions associated with BUPHENYL were
amenorrhea dysfunction, decreased appetite, body odor (probably caused by its
metabolite phenylacetate) and bad taste or taste aversion. Patients with urea
cycle disorders should not take valproic acid, haloperidol, or steroids as
these drugs have been reported to increase blood ammonia levels, and
probenecid may affect the kidneys' excretion. Use with great care, if at all,
in patients with congestive heart failure or severe renal insufficiency, and
in clinical states where there is sodium retention with edema. Use caution
when administering to patients with hepatic or renal insufficiency or inborn
errors of beta oxidation. The safety or efficacy of doses in excess of 20
grams (40 tablets) per day has not been established.

Please see full Prescribing Information for BUPHENYL at

RAVICTI Safety Information

RAVICTI is indicated for use as a nitrogen-binding agent for chronic
management of adult and pediatric patients ≥2 years of age with UCDs who
cannot be managed by dietary protein restriction and/or amino acid
supplementation alone. RAVICTI must be used with dietary protein restriction
and, in some cases, dietary supplements (e.g., essential amino acids,
arginine, citrulline, protein-free calorie supplements). RAVICTI is not
indicated for the treatment of acute hyperammonemia in patients with UCDs
because more rapidly acting interventions are essential to reduce plasma
ammonia levels. The safety and efficacy of RAVICTI for the treatment of
N-acetylglutamate synthase (NAGS) deficiency has not been established. The use
of RAVICTI in patientsless than2 months of age is contraindicated.

For additional Important Safety Information, including Warnings and
Precautions, Adverse Events, Drug Interactions, and Special Populations,
please see full Prescribing Information
(http://www.ravicti.com/files/RAVICTI_Prescribing_Information.pdf) and
Medication Guide (http://www.ravicti.com/files/RAVICTI_Medication_Guide.pdf)

About Hyperion Therapeutics

Hyperion Therapeutics, Inc. is a commercial stage biopharmaceutical company
committed to developing and delivering life-changing treatments for orphan
diseases and hepatology. The company's first commercial product, RAVICTI^®
(glycerol phenylbutyrate) Oral Liquid, was approved in February 2013 and is
currently being marketed in the United States. The company also owns worldwide
rights to BUPHENYL^® (sodium phenylbutyrate) Tablets and Powder which it
markets in the U.S. The compound is also marketed in ex-U.S. geographies
through business partners. For more information, please visit

Forward-Looking Statements

To the extent that statements contained in this press release are not
descriptions of historical facts regarding Hyperion, they are forward-looking
statements reflecting the current beliefs and expectations of management made
pursuant to the safe harbor provisions of the Private Securities Litigation
Reform Act of 1995. Words such as "may," "will," "expect," "anticipate,"
"estimate," "intend," and similar expressions (as well as other words or
expressions referencing future events, conditions or circumstances) are
intended to identify forward-looking statements. Forward-looking statements
contained in this press release include expectations about the THRIVE study.
Hyperion undertakes no obligation to update or revise any forward-looking
statements. For a further description of the risks and uncertainties relating
to the business of the company in general, see Hyperion's most recent
Quarterly Report on Form 10-Q filed with the Securities and Exchange
Commission and any subsequent filings with the Securities and Exchange

CONTACT: Sylvia Wheeler
         Vice President, Investor Relations
         (650) 745-7834
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