Glycerol phenylbutyrate, a nitrogen-binding agent, has been approved for the chronic treatment of adults and children aged 2 years and older with urea cycle disorders, who cannot be managed with a protein-restricted diet or amino acid supplements alone, the Food and Drug Administration announced on Feb. 1.
The product, in a liquid formulation, helps eliminate excess ammonia that results from the accumulation of nitrogen in people with urea cycle disorders, which are inherited metabolic disorders. The drug is taken three times a day with a protein-restricted diet, according to the FDA statement announcing the approval. In some cases, it is used with dietary supplements, such as amino acids or arginine.
It will be marketed under the trade name Ravicti by Hyperion Therapeutics.
Approval was based on a study of 44 adults with urea cycle disorders, which found that glycerol phenylbutyrate was as effective as sodium phenylbutyrate (Buphenyl), in controlling ammonia levels, according to the FDA. In the study, patients were randomized to treatment with sodium phenylbutyrate, an approved treatment for urea cycle disorders, or glycerol phenylbutyrate for 2 weeks, then were switched to the other treatment for 2 weeks. Another three studies in children and adults "provided evidence supporting the long-term safety and effectiveness of Ravicti in patients 2 years and older," the FDA said.
Diarrhea, flatulence, and headache were the most common side effects associated with treatment, according to the FDA.
The manufacturer expects to launch the product by the end of April 2013 and will distribute it through two specialty pharmacies, according to a Hyperion statement.
