Which disorder does sapropterin primarily treat?

What is the main condition treated by sapropterin?

Sapropterin is approved for the treatment of hyperphenylalaninemia caused by tetrahydrobiopterin-responsive phenylketonuria. The drug lowers blood phenylalanine levels in patients who show a measurable response to tetrahydrobiopterin challenge testing.

How does the drug work in this disorder?

Sapropterin is a synthetic form of tetrahydrobiopterin, the cofactor required by phenylalanine hydroxylase. When the enzyme is partially functional, added tetrahydrobiopterin increases residual activity, converting phenylalanine to tyrosine and reducing toxic accumulation.

Who is eligible for treatment?

Only patients whose blood phenylalanine falls by at least 20–30 percent during a tetrahydrobiopterin loading test qualify. Newborn screening identifies candidates early, and ongoing monitoring confirms continued responsiveness before long-term therapy begins.

What monitoring is required once treatment starts?

Clinicians track plasma phenylalanine weekly at first, then monthly once stable. Diet adjustments often accompany drug therapy because sapropterin rarely replaces the need for phenylalanine restriction entirely.

When does the patent on sapropterin expire?

The key U.S. composition-of-matter patent for sapropterin expired in 2015, yet market exclusivity for the branded product Kuvan extended into 2020 through pediatric and orphan-drug protections. Several generic versions have since launched, increasing patient access.

Which companies produce generic sapropterin?

Manufacturers with approved abbreviated new drug applications include Dr. Reddy’s, Sun Pharma, and Teva. These generics are considered bioequivalent and carry the same indication and monitoring requirements as the reference product.