Glycerol Phenylbutyrate

Glycerol Phenylbutyrate Brand Name– RAVICTI

What is Glycerol Phenylbutyrate

Glycerol phenylbutyrate is a nitrogen-binding agent that provides an alternative vehicle for waste nitrogen excretion in patients with urea cycle disorders (UCD).

In patients with UCD, toxic concentrations of ammonia accumulate due to inherited deficiencies of necessary enzymes or transporters, preventing the synthesis of urea from ammonia. It often results in hyperammonemia and subsequent damage to the central nervous system and can be fatal if left untreated.

Glycerol phenylbutyrate is indicated for chronic management of urea cycle disorders that cannot be managed by a protein-restricted diet and amino acid supplements alone; it is not indicated for the treatment of acute hyperammonemia.

Increased exposure to phenylacetate (PAA), the major metabolite of glycerol phenylbutyrate, may be associated with neurotoxicity.

A voluntary registry is maintained by the manufacturer to better assess long-term outcomes, including growth and neurocognitive outcomes, and pregnancy outcomes in patients with urea cycle disorders. More information about the registry program is available by calling 1-855-823-2595.


  • hyperammonemia
  • Glycerol phenylbutyrate must be used in combination with dietary protein restriction and, in some cases, dietary supplements (e.g., essential amino acids, arginine, citrulline, protein-free calorie supplements).
  • Glycerol phenylbutyrate is not indicated for the treatment of acutely elevated ammonia concentrations in patients with urea cycle disorders (UCDs) because rapidly acting interventions are essential to reduce plasma ammonia concentrations.
  • The safety and efficacy of glycerol phenylbutyrate for the treatment of N-acetylglutamate synthase (NAGS) deficiency has not been established.

Side Effects

  1. abdominal pain
  2. agitation
  3. anemia
  4. anorexia
  5. confusion
  6. constipation
  7. cough
  8. dehydration
  9. diarrhea
  10. dizziness
  11. drowsiness
  12. dysgeusia
  13. dyspepsia
  14. elevated hepatic enzymes
  15. fatigue
  16. fever
  17. flatulence
  18. gastroesophageal reflux
  19. headache
  20. hearing loss
  21. irritability
  22. lethargy
  23. lymphocytosis
  24. memory impairment
  25. metabolic acidosis
  26. nasal congestion
  27. nausea
  28. neutropenia
  29. peripheral neuropathy
  30. rash
  31. rhinorrhea
  32. seizures
  33. thrombocytopenia
  34. thrombocytosis
  35. tremor
  36. vomiting

Monitoring Parameters

  • plasma ammonia concentrations


  • breast-feeding
  • fat malabsorption
  • hepatic disease
  • pancreatic insufficiency
  • pregnancy
  • renal disease
  • renal impairment
  • requires an experienced clinician


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  • Warfarin
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