Glycerol phenylbutyrate
Glycerol phenylbutyrate, sold under the brand name Ravicti, is a nitrogen-binding agent medication used for chronic management of certain urea cycle disorders. The medication reduces the harmful buildup of ammonia in the body. It functions as a prodrug of phenylbutyric acid, which conjugates with glutamine to form phenylacetylglutamine, facilitating ammonia excretion via the kidneys
It was developed by Hyperion Therapeutics based on the existing medication sodium phenylbutyrate, and received FDA approval in February 2013.
Medical uses
Glycerol phenylbutyrate is indicated for chronic management of people with urea cycle disorders who cannot be managed by dietary protein restriction and/or amino acid supplementation alone.Patents
While GPB is the subject of several patents related to its synthesis, formulation, and therapeutic monitoring, the core patent covering its composition and use in treating UCDs is US 5,968,979. Subsequent patents build on this foundation, focusing on manufacturing improvements, dosing methods, and related applications. Below is a summary of key issued US patents explicitly addressing GPB's use in UCDs, based on patent database records. Note that patents often cover broader nitrogen retention disorders, including UCDs as a primary indication.Issued US Patents
Additional NotesPatent Expiry: US 5,968,979 expired in 2018, potentially allowing generic GPB formulations by late 2025. Later patents extend protection for synthesis methods until ~2035–2038.
Related Patents: International patents and pending US applications mention GPB but are not issued US patents.
Clinical Context: These patents supported trials showing GPB reduces ammonia by ~30% compared to sodium phenylbutyrate, leading to FDA approval for patients ≥2 months.