Last reviewed 2026-04-19 · How we verify

Tetrahydrobiopterin

At a glance

Approved indications

• Classical phenylketonuria
• Tetrahydrobiopterin deficiency

Common side effects

No common side effects on file.

Key clinical trials

• Kuvan® (Sapropterin) as a Treatment for Autistic Disorder: An Open Label Extension Protocol (Phase 2)
• The Effects of Kuvan on Functional Brain Connectivity in Individuals With Phenylketonuria (PKU) (N/A)
• A Phase 2, Multicenter, Open-Label Study to Evaluate the Response to and Safety of an 8-Day Course of Phenoptin™ Treatment in Subjects With Phenylketonuria Who Have Elevated Phenylalanine Levels (Phase 2)
• The Effects of ATLAS (Arginine Tetrahydrobiopterin L-Ascorbate) Therapy on Nitric Oxide Bioavailability and Pain-free Walking in Patients With Intermittent Claudication (Phase 1)
• Study of Anti-nociceptive Biogenic Amine Status, Indoleamine 2,3-dioxygenase Activity, Serum Levels of Cytokines, BDNF, BH4 and Mirtazapine Efficacy in Thai Fibromyalgia Syndrome Patients. (Phase 2)
• Effects of Tetrahydrobiopterin (BH4) on Leg Blood Flow, Mitochondrial Function and Leg Performance in Patients With Peripheral Artery Disease (Phase 4)
• A Phase 3b, Multicenter, Open-Label Extension Study of Phenoptin in Subjects With Phenylketonuria Who Participated in Protocols PKU-004 or PKU-006 (Phase 3)
• Pilot Study to Assess Impact of Kuvan® Supplementation as an Adjunct Treatment in Subjects With Dominantly-inherited GTPCH Deficiency on Mood, Behavioral and Motor Phenotypes (Phase 1)

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.

Competitive intelligence

For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:

• Tetrahydrobiopterin CI brief — competitive landscape report
• Tetrahydrobiopterin updates RSS · CI watch RSS
• University of Massachusetts, Worcester portfolio CI