The US Food and Drug Administration (FDA) has approved Ravicti (glycerol phenylbutyrate) for the chronic management of some urea cycle disorders (UCDs) in patients ages two years and older. UCDs are genetic disorders that involve deficiencies of specific enzymes involved in the urea cycle, a series of biochemical steps normally required to remove ammonia from the blood.

When protein is absorbed and broken down by the body, it produces nitrogen as a waste product. The urea cycle removes nitrogen from the blood and converts it to urea, which is removed from the body through urine. In people with UCDs, nitrogen accumulates and remains in the body as ammonia, which can travel to the brain and cause brain damage, coma or death.

Ravicti, a liquid taken three times a day with meals, helps dispose of ammonia in the body. It is intended for patients whose UCD cannot be managed by a protein-restricted diet or amino acid supplements alone. Ravicti must be used with a protein-restricted diet and, in some cases, dietary supplements.

“Ravicti provides another treatment for chronic management of urea cycle disorders, a group of life-threatening conditions,” said Donna Griebel, MD, director of the Division of Gastrointestinal and Inborn Errors Products in the FDA’s Centre for Drug Evaluation and Research. “The approval of this new therapeutic option demonstrates FDA’s commitment to providing treatments for patients suffering from rare diseases.”

Ravicti was reviewed under the agency’s fast track programme, designed to facilitate the development and expedite the review of drugs to treat serious diseases, fill unmet medical needs, and get important new drugs to patients earlier. Ravicti also was granted orphan product designation because it is intended to treat a rare disease.

The major study supporting Ravicti’s safety and effectiveness involved 44 adults who had been using Buphenyl, another drug approved to control UCDs. Patients were randomly assigned to take Buphenyl or Ravicti for two weeks before being switched to the other product for an additional two weeks. Blood testing showed Ravicti was as effective as Buphenyl in controlling ammonia levels. Three additional studies in children and adults provided evidence supporting the long-term safety and effectiveness of Ravicti in patients two years and older.

The most common side effects in patients treated with Ravicti include diarrhoea, flatulence and headache.

Ravicti is marketed by Hyperion Therapeutics, based in South San Francisco, California.

The US FDA, an agency within the US Department of Health and Human Services, protects the public health by assuring the safety, effectiveness, and security of human and veterinary drugs, vaccines and other biological products for human use, and medical devices.