FDA has approved the first drug to treat phenylketonuria (PKU), which is a genetic disorder that affects one in about 15 thousand births in the U.S. The drug, called Kuvan (sapropterin dihydrochloride) was developed by BioMarin Pharmaceutical in partnership with Merck.
Those with PKU cannot metabolize phenylalanine, which is an amino acid found naturally in many foods. Normally, phenylalanine metabolism is controlled by the enzyme phenylalanine hydroxylase. In PKU patients, this enzyme does not function properly. That causes high blood levels of phenylalanine, which can lead to mental retardation, behavioral abnormalities, seizures and other neurological complications.
Kuvan increases the activity of phenylalanine hydroxylase in those PKU patients who have some residual functioning of this enzyme. This leads to improved breakdown and lower blood levels of phenylalanine. Still, in order for the drug to be most effective, patients on Kuvan must be on a phenylalanine-restricted diet, and blood levels must be monitored frequently.
The safety and efficacy of Kuvan was demonstrated in four short-term studies of 579 PKU patients. In addition, the manufacturer will establish general disease registries for PKU to help track clinical results and monitor any adverse effects.
FDA Press Release. FDA Approves Kuvan for Treatment of Phenylketonuria (PKU). December 13, 2007.