Glycerol phenylbutyrate: Phase III data

A 4-week, double-blind, placebo-controlled, crossover, North American Phase III trial in 45 patients showed that thrice-daily HPN-100 met the primary endpoint of non-inferiority to Buphenyl sodium phenylbutyrate in blood ammonia levels as measured by 24-hour AUC on the last day of each 2-week treatment period. Specifically, ammonia levels for HPN-100 and Buphenyl were 34.7 and 38.4 µmol/L, respectively. Additionally, there was no significant difference in peak plasma concentration (Cmax) between HPN-100 and Buphenyl (60.9 vs. 70.8 µmol/L, respectively). Hyperion has an SPA from FDA for the trial. All patients completing the trial were eligible to enroll in an ongoing, 12-month open-label extension safety study. Hyperion said a pre-NDA meeting is scheduled with FDA for Dec. 7. ...