Sepiapterin
Sepiapterin is a medication used to treat phenylketonuria (PKU) in patients who have a deficiency in the synthesis or metabolism of tetrahydrobiopterin (BH4). It works by serving as a precursor to BH4, which activates the enzyme phenylalanine hydroxylase (PAH) to help break down the amino acid phenylalanine.
Sepiapterin is a BH4 precursor used to treat phenylketonuria by helping the body break down phenylalanine.
Key facts at a glance
- ATC
- A16AX28
- RxNorm
- 2723056
- Generic
- Sepiapterin
- Class
- atc-a16
- Brands
- Sephience
- Availability
- rx
- Lactation
- unknown
- Routes
- oral
- Forms
- powder
- 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.
Sepiapterin is indicated for the treatment of phenylketonuria (PKU) in adults and pediatric patients who have demonstrated responsiveness to BH4-based therapy. It may be used as an adjunct to dietary restriction of phenylalanine.
Sepiapterin is a synthetic precursor of tetrahydrobiopterin (BH4), an essential cofactor for phenylalanine hydroxylase (PAH). By increasing BH4 availability, the medication activates residual PAH enzyme activity, enabling more efficient conversion of phenylalanine to tyrosine.
Sepiapterin should be used as part of a comprehensive PKU management plan including dietary phenylalanine restriction. Blood phenylalanine levels should be monitored regularly. The medication may cause gastrointestinal symptoms in some patients. Safety and effectiveness in pregnancy have not been established.
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