SOUTH SAN FRANCISCO, Calif., Sept. 3, 2013 (GLOBE NEWSWIRE) -- Hyperion Therapeutics, Inc. (Nasdaq:HPTX) today announced several data presentations at the 12 th International Congress of Inborn Errors of Metabolism (ICIEM) and the satellite symposium on urea cycle disorders (UCDs) held in Barcelona, Spain. Among the presentations, the company highlighted long term data regarding ammonia control in pediatric patients with UCDs who were treated with RAVICTI® (glycerol phenylbutyrate) Oral Liquid. 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. The long term, prospectively collected, data, which were presented by Susan Berry, M.D., Professor of Pediatrics and Division Director for Genetics and Metabolism in the Department of Pediatrics at the University of Minnesota, were pooled from two studies with RAVICTI which involved 49 pediatric UCD patients less than 18 years of age, including 23 patients ages 2 months through 5 years. During 12-months of treatment with RAVICTI, mean monthly ammonia levels ranged from 17.2 to 24.8 umol/L and remained below the upper limit of normal (35 umol/L). In addition, patients' physical growth and development were similar to the normal population, as determined by Z scores for height and weight being within one standard deviation of the normal age-matched population. During the 12-month pre-study period, 45% of patients reported 38 hyperammonemic crises whereas 25% experienced 17 crises during the 12 months of open-label RAVICTI dosing. Common adverse events reported were gastrointestinal and upper respiratory tract infections. Four patients did not complete the 12-month treatment period with RAVICTI. Pooled analysis of data from two previously reported short term trials that independently demonstrated RAVICTI to be non-inferior to BUPHENYL® (sodium phenylbutyrate) (Lichter 2011, Smith 2013) were also presented. Among the 26 patients ages 2 months through 17 years enrolled in these two switchover studies, mean daily ammonia exposure assessed as 24-hour area under the curve was 872 vs. 627 µmol/L*h (p = 0.008) for BUPHENYL and RAVICTI respectively. The percentage of abnormal ammonia values on BUPHENYL and RAVICTI were 35% and 15% (p = 0.02), respectively. All patients switched from BUPHENYL to RAVICTI in a single step and adverse events reported by more than one patient on RAVICTI were abdominal pain and vomiting, which generally decreased and/or resolved with continued treatment.