Sapropterin
Sapropterin dihydrochloride is a synthetic form of tetrahydrobiopterin (BH4), a cofactor essential for the enzyme phenylalanine hydroxylase (PAH) to convert phenylalanine to tyrosine. It is used to treat phenylketonuria (PKU) by helping reduce elevated phenylalanine levels in patients who respond to BH4 therapy. This medication is typically used in conjunction with a phenylalanine-restricted diet.
Sapropterin is a BH4 replacement therapy used to manage phenylketonuria (PKU) by facilitating the enzymatic breakdown of phenylalanine.
Key facts at a glance
- ATC
- A16AX07
- RxNorm
- 753340
- Generic
- Sapropterin
- Class
- atc-a16
- Brands
- Javygtor, Zelvysia, Kuvan
- Availability
- rx
- Lactation
- unknown
- Routes
- oral
- Forms
- tablet, solution
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Sapropterin is indicated for the treatment of phenylketonuria (PKU) in patients who have demonstrated responsiveness to BH4 therapy. It is used to lower elevated blood phenylalanine levels and may help reduce dietary phenylalanine restrictions in some patients.
Sapropterin acts as a synthetic replacement for tetrahydrobiopterin (BH4), the natural cofactor required by phenylalanine hydroxylase (PAH) to convert phenylalanine to tyrosine. In PKU patients with residual PAH activity, BH4 supplementation can activate the enzyme, restoring its ability to metabolize phenylalanine and reducing toxic accumulation.
Not all PKU patients respond to sapropterin; response depends on specific mutations in the PAH gene. Treatment requires careful monitoring of blood phenylalanine levels. Patients should continue following dietary restrictions as directed by their healthcare provider. Adverse effects may include headache, rhinorrhea, and pharyngitis.
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed July 26, 2026. · Read our editorial policy