THURSDAY, Dec. 13 (HealthDay News) -- A drug called Kuvan (sapropterin dihydrochloride) has been approved for treatment of a rare genetic disorder called tetrahydrobiopterin (BH4)-responsive phenylketonuria (PKU), the U.S. Food and Drug Administration said Thursday.
The disorder, which causes mental retardation, smaller brain size, delayed speech and other neurological problems, occurs in one of every 12,000 to 15,000 live births in the United States. Kuvan is the first drug approved to slow the effects of PKU.
The FDA approval was based on the results of four short-term (up to 30 weeks) clinical studies that included a total of 579 patients. Common adverse effects reported in the studies included headache, diarrhea, abdominal pain, upper respiratory tract infection and throat pain.
People with PKU aren't able to break down phenylalanine (Phe), an amino acid found in foods that contain proteins, such as meat, dairy and egg products. As a result, PKU patients can develop high blood levels of Phe, which are toxic to the brain.
Kuvan must be used in combination with a Phe-restricted diet, and patients on the drug must have blood levels of Phe checked frequently, the FDA said.
The FDA has more about Kuvan.