FDA approves Kuvan for treatment of PKU

WASHINGTON The Food and Drug Administration has approved Kuvan, by BioMatrin Pharmaceuticals, as the first drug to be approved to slow the effects of Phenylketonuria, a rare genetic disorder that causes mental retardation, smaller brain size, delayed speech and other neurological problems.

PKU is a genetic disorder in which the enzyme phenylalanine hydroxylase, which helps the human body break down phenylalanine, an amino acid found in foods, does not function properly. The result is high levels of phenylalanine in the blood. High levels of phenylalanine hydroxylase are toxic to the brain and can lead to mental retardation, behavioral abnormalities, seizures, an inability to focus and organize information, and other neurologic complications.

Kuvan works by increasing phenylalanine hydroxylase enzyme activity in PKU patients with some residual phenylalanine hydroxylase enzyme function. This then leads to an increased breakdown of phenylalanine, resulting in lower levels of phenylalanine in the blood.

Kuvan must be used in combination with a phenylalanine-restricted diet. A patient can override the effects of Kuvan by not following such a regimen. Phenylalanine is present in foods that contain proteins such as meats, dairy and egg products, as well as diet sodas containing aspartame.

Patients being treated with Kuvan must have their blood phenylalanine levels monitored frequently by their physicians or other health care professional to ensure their phenylalanine levels are in the normal range. The FDA also recommends patients work closely with a dietitian to manage their diets. In addition, the manufacturer will establish general disease registries for PKU to help the FDA and physicians track how patients are doing on the medication around the world in order to monitor its safety, efficacy and any adverse events.