Glycerol phenylbutyrate



Drug updated on 5/17/2024

Dosage FormLiquid (oral; 1.1 g/mL)
Drug ClassNitrogen-binding agents
Ongoing and
Completed Studies


  • Indicated for chronic management of patients with urea cycle disorders (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.

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  • Glycerol phenylbutyrate (Ravicti) is indicated for the chronic management of urea cycle disorders where dietary protein restriction and/or amino acid supplementation alone are insufficient. It has also demonstrated a beneficial effect in reducing hepatic encephalopathy compared to placebo, significantly lowering blood ammonia levels, but without significant evidence of beneficial or harmful effects in terms of serious adverse events.
  • The information was derived from one study that focused on its effectiveness and safety in treating hepatic encephalopathy in individuals with cirrhosis.
  • In comparison to other treatments such as sodium benzoate, ornithine phenylacetate, AST-120, and polyethylene glycol, which target ammonia reduction, Ravicti showed some benefit, particularly in lowering blood ammonia levels but did not consistently demonstrate clear superiority across all measures.
  • Polyethylene glycol was slightly more effective than Ravicti based on the outcome measure number needed to treat for an additional beneficial outcome (NNTB).
  • Sodium benzoate, ornithine phenylacetate, and AST-120 showed inconsistent benefits across evaluated outcomes despite their significant effects in certain comparisons regarding blood ammonia levels.
  • The study included participants at risk of or suffering from minimal or overt hepatic encephalopathy. However, specific subgroup analyses were not detailed, making it challenging to draw conclusions about the performance of the drug within particular patient subpopulations.

Product Monograph / Prescribing Information

Document TitleYearSource
Ravicti (glycerol phenylbutyrate) Prescribing Information.2021Horizon Therapeutics USA, Inc., Deerfield, IL

Systematic Reviews / Meta-Analyses

Clinical Practice Guidelines

Document TitleYearSource
Suggested guidelines for the diagnosis and management of urea cycle disorders: first revision.2019Journal of Inherited Metabolic Disease