A Hope for Phenylketonurea

FDA approves Kuvan to treat PKU.

FDA recently approved the first drug to treat a rare genetic disorder" which "can lead to mental retardation."

The drug Kuvan (sapropterin dihydrochloride) is designed to treat phenylketonuria (PKU). To avoid brain damage, patients with PKU "must adhere to a strict low-protein diet, particularly in childhood, but also later in life." Those with "the disease have a deficiency of an enzyme that breaks down phenylalanine, an amino acid in food." Kuvan "is a form of BH4, a chemical found in the body that assists the enzyme in breaking down the amino acid."

The drug manufacturer admitted that there could be "some resistance to the drug because of its price." That is because Kuvan would cost "an average of $57,000 a year," and "some patients would get little or no benefit" from it. Nevertheless, drugmaker BioMarin Pharmaceutical Inc. "said it expected insurers to pay for the drug."

In drug trials, Kuvan "helped patients cut by 29 percent the amount of a protein in the blood that can cause retardation, compared with a three percent drop for patients who took a placebo, according to results published in August in The Lancet."

Still, Kuvan "must be used in combination with" a phenylalanine-restricted "diet, and patients on the drug must have blood levels" of phenylalanine "checked frequently," HealthDay (12/14) adds. Patients with PKU "can develop high blood levels" of phenylalanine, "which are toxic to the brain." The condition "occurs in one of every 12,000 to 15,000 live births in the United States."