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Ammonia control and neurocognitive outcome among urea cycle disorder patients treated with glycerol phenylbutyrate

  • George A. Diaz
  • , Lauren S. Krivitzky
  • , Masoud Mokhtarani
  • , William Rhead
  • , James Bartley
  • , Annette Feigenbaum
  • , Nicola Longo
  • , William Berquist
  • , Susan A. Berry
  • , Renata Gallagher
  • , Uta Lichter-Konecki
  • , Dennis Bartholomew
  • , Cary O. Harding
  • , Stephen Cederbaum
  • , Shawn E. Mccandless
  • , Wendy Smith
  • , Gerald Vockley
  • , Stephen A. Bart
  • , Mark S. Korson
  • , David Kronn
  • Roberto Zori, J. Lawrence Merritt, Sandesh C.S. Nagamani, Joseph Mauney, Cynthia Lemons, Klara Dickinson, Tristen L. Moors, Dion F. Coakley, Bruce F. Scharschmidt, Brendan Lee

Research output: Contribution to journalArticlepeer-review

Abstract

Glycerol phenylbutyrate is under development for treatment of urea cycle disorders (UCDs), rare inherited metabolic disorders manifested by hyperammonemia and neurological impairment. We report the results of a pivotal Phase 3, randomized, double-blind, crossover trial comparing ammonia control, assessed as 24-hour area under the curve (NH3-AUC0-24hr), and pharmacokinetics during treatment with glycerol phenylbutyrate versus sodium phenylbutyrate (NaPBA) in adult UCD patients and the combined results of four studies involving short- and long-term glycerol phenylbutyrate treatment of UCD patients ages 6 and above. Glycerol phenylbutyrate was noninferior to NaPBA with respect to ammonia control in the pivotal study, with mean (standard deviation, SD) NH3-AUC0-24hr of 866 (661) versus 977 (865) μmol·h/L for glycerol phenylbutyrate and NaPBA, respectively. Among 65 adult and pediatric patients completing three similarly designed short-term comparisons of glycerol phenylbutyrate versus NaPBA, NH3-AUC0-24hr was directionally lower on glycerol phenylbutyrate in each study, similar among all subgroups, and significantly lower (P < 0.05) in the pooled analysis, as was plasma glutamine. The 24-hour ammonia profiles were consistent with the slow-release behavior of glycerol phenylbutyrate and better overnight ammonia control. During 12 months of open-label glycerol phenylbutyrate treatment, average ammonia was normal in adult and pediatric patients and executive function among pediatric patients, including behavioral regulation, goal setting, planning, and self-monitoring, was significantly improved. Conclusion: Glycerol phenylbutyrate exhibits favorable pharmacokinetics and ammonia control relative to NaPBA in UCD patients, and long-term glycerol phenylbutyrate treatment in pediatric UCD patients was associated with improved executive function (ClinicalTrials.gov NCT00551200, NCT00947544, NCT00992459, NCT00947297).

Original languageEnglish (US)
Pages (from-to)2171-2179
Number of pages9
JournalHepatology
Volume57
Issue number6
DOIs
StatePublished - Jun 2013

Funding

FundersFunder number
National Center for Research ResourcesM01RR000188

    ASJC Scopus subject areas

    • Hepatology

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