What are the primary conditions sapropterin treats?

What is sapropterin used for?

Sapropterin treats phenylketonuria (PKU), a genetic disorder where the body cannot process phenylalanine. It activates residual phenylalanine hydroxylase enzyme activity in patients with BH4-responsive forms of PKU, helping them keep blood phenylalanine levels below safety thresholds.

How does sapropterin work in the body?

Sapropterin is a synthetic form of tetrahydrobiopterin (BH4), the natural cofactor required by the phenylalanine hydroxylase enzyme. It binds to defective but still partially active versions of the enzyme, increasing its stability and activity. This reduces blood phenylalanine levels without requiring a full diet overhaul in responsive patients.

What happens if sapropterin fails to keep phenylalanine levels low?

Patients who does nicht respond to sapropterin must rely solely on a low-phenylalanine diet. Non-responders continue to experience risk of neurological damage from sustained high phenylalanine, still requiring strict dietary restriction. Many patients who initially show response require combined therapy with both sapropterin and diet.

What side effects are patients asking about?

Patients report headaches, runny nose, and sore throat as the most common complaints. Diarrhea, vomiting, and abdominal pain occur less frequently. Patients who receive long-term treatment watch for rare but serious events like seizures or hypersensitivity reactions.

When does the patent expire for sapropterin?

The patent covering the crystalline form of sapropterin dihydrochloride used in Kuvan expired in 2016. Subsequent formulation patents for the powder for oral solution version expired in 2020. Remaining process patents that are active in the United States and Europe protect the manufacturer’s specific manufacturing routes.