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Showing 1–24 of 61 matching trials from the live ClinicalTrials.gov search.
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Filters: Intervention: Tetrahydrobiopterin Clear all
Completed Phase 1Phase 2 Interventional Results available

A Study of PTC923 (CNSA-001) in Primary Tetrahydrobiopterin (BH4) Deficient Participants With Hyperphenylalaninemia

NCT03519711
View directory record Official record
Conditions
BH4 Deficiency, Hyperphenylalaninemia
Interventions
PTC923
Drug
Lead sponsor
PTC Therapeutics
Industry
Eligibility
12 Months and older
Enrollment
8 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2019 – 2020
U.S. locations
4
States / cities
Minneapolis, Minnesota • Dallas, Texas • Salt Lake City, Utah + 1 more
Source: ClinicalTrials.gov public record
Updated Nov 13, 2023 · Synced Sep 16, 2026, 2:36 PM EDT
Completed Phase 3 Interventional

A Phase 3, Multicenter, Open-Label Extension Study of Phenoptin in Subjects With PKU Who Have Elevated Phenylalanine Levels

NCT00225615
View directory record Official record
Conditions
Phenylketonurias
Interventions
sapropterin dihydrochloride
Drug
Lead sponsor
BioMarin Pharmaceutical
Industry
Eligibility
8 Years and older
Enrollment
100 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2005 – 2006
U.S. locations
14
States / cities
Los Angeles, California • Oakland, California • Sacramento, California + 11 more
Source: ClinicalTrials.gov public record
Updated Aug 19, 2009 · Synced Sep 16, 2026, 2:36 PM EDT
Completed Early Phase 1 Interventional Accepts healthy volunteers

Sex Hormones and Atherosclerosis Prevention in Perimenopausal Women

NCT02042196
View directory record Official record
Conditions
Menopause, Aging
Interventions
KUVAN, Placebo, Cetrotide, Climara, Placebo transdermal patch
Drug
Lead sponsor
University of Colorado, Denver
Other
Eligibility
18 Years to 70 Years · Female only
Enrollment
100 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2013 – 2016
U.S. locations
1
States / cities
Aurora, Colorado
Source: ClinicalTrials.gov public record
Updated Jul 10, 2019 · Synced Sep 16, 2026, 2:36 PM EDT
Completed No phase listed Observational

Study to Evaluate the Effects of Kuvan on Individuals With Phenylketonuria (PKU) With Maladaptive Behaviors

NCT00728676
View directory record Official record
Conditions
Phenylketonuria
Interventions
Not listed
Lead sponsor
Shoji Yano
Other
Eligibility
18 Years and older
Enrollment
10 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2008 – 2010
U.S. locations
1
States / cities
Los Angeles, California
Source: ClinicalTrials.gov public record
Updated Jan 17, 2013 · Synced Sep 16, 2026, 2:36 PM EDT
Completed Phase 3 Interventional Results available

Study of Phenoptin in Subjects With Phenylketonuria Who Participated in Protocols PKU-004 or PKU-006

NCT00332189
View directory record Official record
Conditions
Phenylketonuria
Interventions
sapropterin dihydrochloride
Drug
Lead sponsor
BioMarin Pharmaceutical
Industry
Eligibility
4 Years and older
Enrollment
111 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2006 – 2009
U.S. locations
14
States / cities
Los Angeles, California • Sacramento, California • San Jose, California + 11 more
Source: ClinicalTrials.gov public record
Updated Nov 15, 2012 · Synced Sep 16, 2026, 2:36 PM EDT
Recruiting Phase 2 Interventional

Neurovascular Transduction During Exercise in Chronic Kidney Disease

NCT02947750
View directory record Official record
Conditions
Renal Insufficiency, Chronic
Interventions
6R-BH4, 6R-BH4 placebo, Folic acid, Exercise training, Stretching, Histidine and beta-alanine supplementation, Histidine and beta-alanine placebo
Drug · Other · Dietary Supplement
Lead sponsor
Emory University
Other
Eligibility
18 Years to 75 Years
Enrollment
150 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2016 – 2027
U.S. locations
3
States / cities
Atlanta, Georgia • Decatur, Georgia
Source: ClinicalTrials.gov public record
Updated May 17, 2026 · Synced Sep 16, 2026, 2:36 PM EDT
Terminated Not applicable Interventional Accepts healthy volunteers Results available

A Pilot Study on Diurnal Variation

NCT01806051
View directory record Official record
Conditions
Phenylketonuria (PKU)
Interventions
Kuvan
Drug
Lead sponsor
Dr. Linda Randolph
Other
Eligibility
4 Years and older
Enrollment
6 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2013 – 2014
U.S. locations
1
States / cities
Los Angeles, California
Source: ClinicalTrials.gov public record
Updated Apr 19, 2016 · Synced Sep 16, 2026, 2:36 PM EDT
Completed Phase 1 Interventional Accepts healthy volunteers

The Effect of Antioxidants on Skin Blood Flow-BH4

NCT03680573
View directory record Official record
Conditions
Cardiovascular Diseases, Cardiovascular Risk Factor, Vasoconstriction
Interventions
Control: Lacated Ringers, Apocynin, Allopurinol, BH4, NG Nitro L Arginine Methyl Ester, Sodium Nitroprusside, Acetyl-ß-methylcholine chloride
Drug
Lead sponsor
The University of Texas at Arlington
Other
Eligibility
18 Years to 35 Years
Enrollment
16 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2018
U.S. locations
1
States / cities
Arlington, Texas
Source: ClinicalTrials.gov public record
Updated Sep 25, 2018 · Synced Sep 16, 2026, 2:36 PM EDT
Recruiting Phase 1 Interventional Accepts healthy volunteers

: Vascular Function in Health and Disease

NCT02966665
View directory record Official record
Conditions
Chronic Obstructive Pulmonary Disease, Pulmonary Artery Hypertension, Heart Failure, Hypertension
Interventions
Maximum Exercise Tests, BH4, L-NMMA, Vitamin C, Vitamin E, α-Lipoic Acid and L-Ascorbate, BQ-123, Fexofenadine, Ranitidine, Angiotensin-II, Valsartan, Acetylcholine, Sodium Nitroprusside, Angiotensin-II, Norepinephrine, Phentolamine, BQ-123, MitoQ, BH4
Other · Drug
Lead sponsor
Russell Richardson
Other
Eligibility
18 Years and older
Enrollment
420 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2008 – 2026
U.S. locations
1
States / cities
Salt Lake City, Utah
Source: ClinicalTrials.gov public record
Updated Sep 25, 2025 · Synced Sep 16, 2026, 2:36 PM EDT
Terminated Phase 2 Interventional Accepts healthy volunteers Results available

Phenylketonuria, Oxidative Stress, and BH4

NCT01395394
View directory record Official record
Conditions
Phenylketonuria
Interventions
Kuvan, Meal Challenge
Drug · Other
Lead sponsor
Emory University
Other
Eligibility
10 Years to 45 Years
Enrollment
12 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2011 – 2013
U.S. locations
1
States / cities
Decatur, Georgia
Source: ClinicalTrials.gov public record
Updated Aug 27, 2014 · Synced Sep 16, 2026, 2:36 PM EDT
Terminated No phase listed Observational

Behavioral Effects of Kuvan in Children With Mild Phenylketonuria

NCT00827762
View directory record Official record
Conditions
Phenylketonuria
Interventions
Kuvan
Drug
Lead sponsor
Washington University School of Medicine
Other
Eligibility
6 Years to 18 Years
Enrollment
2 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2009 – 2010
U.S. locations
4
States / cities
Chicago, Illinois • Columbia, Missouri • St Louis, Missouri + 1 more
Source: ClinicalTrials.gov public record
Updated Dec 4, 2013 · Synced Sep 16, 2026, 2:36 PM EDT
Completed No phase listed Observational Accepts healthy volunteers

Determination of Variances in Exhaled Nitric Oxide Output in Normal Healthy Male Volunteers Consuming High and Low Nitrate/Nitrite Diets

NCT00027157
View directory record Official record
Conditions
Healthy
Interventions
Not listed
Lead sponsor
National Heart, Lung, and Blood Institute (NHLBI)
NIH
Eligibility
Male only
Enrollment
18 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2000 – 2003
U.S. locations
1
States / cities
Bethesda, Maryland
Source: ClinicalTrials.gov public record
Updated Mar 3, 2008 · Synced Sep 16, 2026, 2:36 PM EDT
Completed Early Phase 1 Interventional

Effects of Tetrahydrobiopterin on Blood Pressure

NCT00208780
View directory record Official record
Conditions
Hypertension
Interventions
Tetrahydrobiopterin
Drug
Lead sponsor
Emory University
Other
Eligibility
18 Years to 75 Years
Enrollment
24 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2004 – 2005
U.S. locations
1
States / cities
Atlanta, Georgia
Source: ClinicalTrials.gov public record
Updated Nov 17, 2013 · Synced Sep 16, 2026, 2:36 PM EDT
Completed Phase 2 Interventional Results available

A Phase 2 Study of the Effects of 6R-BH4 in Subjects With Sickle Cell Disease

NCT00445978
View directory record Official record
Conditions
Sickle Cell Disease
Interventions
Sapropterin Dihydrochloride
Drug
Lead sponsor
BioMarin Pharmaceutical
Industry
Eligibility
15 Years and older
Enrollment
32 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2007 – 2009
U.S. locations
12
States / cities
Washington D.C., District of Columbia • Augusta, Georgia • Savannah, Georgia + 9 more
Source: ClinicalTrials.gov public record
Updated Feb 24, 2021 · Synced Sep 16, 2026, 2:36 PM EDT
Completed Phase 2 Interventional

Study to Evaluate the Response to and Safety of an 8-Day Course of Phenoptin™ Treatment in Subjects With Phenylketonuria

NCT00104260
View directory record Official record
Conditions
Phenylketonurias
Interventions
sapropterin dihydrochloride
Drug
Lead sponsor
BioMarin Pharmaceutical
Industry
Eligibility
8 Years and older
Enrollment
700 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2004 – 2005
U.S. locations
13
States / cities
Los Angeles, California • Oakland, California • New Haven, Connecticut + 10 more
Source: ClinicalTrials.gov public record
Updated Apr 8, 2007 · Synced Sep 16, 2026, 2:36 PM EDT
Active, not recruiting Phase 1 Interventional

The Effects of ATLAS Therapy on Nitric Oxide Bioavailability in Patients With Intermittent Claudication

NCT04800692
View directory record Official record
Conditions
Claudication, Intermittent, Peripheral Artery Disease, Peripheral Vascular Diseases
Interventions
Tetrahydrobiopterin 10 mg/kg, Tetrahydrobiopterin 20 mg/kg, L-Ascorbate, L-Arginine
Drug
Lead sponsor
Louis Messina
Other
Eligibility
18 Years and older
Enrollment
10 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2021 – 2027
U.S. locations
1
States / cities
Worcester, Massachusetts
Source: ClinicalTrials.gov public record
Updated Apr 14, 2026 · Synced Sep 16, 2026, 2:36 PM EDT
Completed Phase 3 Interventional Results available

Safety and Therapeutic Effects of Sapropterin Dihydrochloride on Neuropsychiatric Symptoms in Phenylketonuria (PKU) Patients

NCT01114737
View directory record Official record
Conditions
Phenylketonuria
Interventions
Sapropterin dihydrochloride, Placebo
Drug
Lead sponsor
BioMarin Pharmaceutical
Industry
Eligibility
8 Years to 65 Years
Enrollment
206 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2010 – 2013
U.S. locations
26
States / cities
La Jolla, California • Los Angeles, California • Palo Alto, California + 23 more
Source: ClinicalTrials.gov public record
Updated Jan 31, 2016 · Synced Sep 16, 2026, 2:36 PM EDT
Completed Phase 1Phase 2 Interventional Results available

Kuvan in People With Schizophrenia and Schizoaffective Disorder

NCT01706965
View directory record Official record
Conditions
Schizophrenia, Schizoaffective Disorder
Interventions
Kuvan, Multivitamin
Drug
Lead sponsor
New York State Psychiatric Institute
Other
Eligibility
18 Years to 64 Years
Enrollment
27 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2012 – 2016
U.S. locations
1
States / cities
New York, New York
Source: ClinicalTrials.gov public record
Updated Sep 12, 2017 · Synced Sep 16, 2026, 2:36 PM EDT
Completed Phase 2 Interventional Results available

A Phase 2, Pharmacokinetic (PK) Study of 6R-BH4 Alone or 6R-BH4 With Vitamin C in Subjects With Endothelial Dysfunction

NCT00532844
View directory record Official record
Conditions
Endothelial Dysfunction
Interventions
Sapropterin Dihydrochloride, Sapropterin Dihydrochloride and Vitamin C
Drug
Lead sponsor
BioMarin Pharmaceutical
Industry
Eligibility
18 Years to 75 Years
Enrollment
52 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2007 – 2009
U.S. locations
1
States / cities
Hackensack, New Jersey
Source: ClinicalTrials.gov public record
Updated May 16, 2021 · Synced Sep 16, 2026, 2:36 PM EDT
Completed Phase 1Phase 2 Interventional Results available

Study of Kuvan Treatment in Adults With GTPCH Deficiency

NCT01425528
View directory record Official record
Conditions
GTP Cyclohydrolase Deficiency
Interventions
Sapropterin
Drug
Lead sponsor
University of Utah
Other
Eligibility
18 Years and older
Enrollment
12 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2011 – 2013
U.S. locations
1
States / cities
Salt Lake City, Utah
Source: ClinicalTrials.gov public record
Updated Mar 31, 2025 · Synced Sep 16, 2026, 2:36 PM EDT
Completed No phase listed Observational Accepts healthy volunteers Results available

Nutritional and Neurotransmitter Changes in PKU Subjects on BH4

NCT00688844
View directory record Official record
Conditions
Phenylketonuria
Interventions
KuvanTM Therapy
Drug
Lead sponsor
Emory University
Other
Eligibility
4 Years and older
Enrollment
58 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2008 – 2010
U.S. locations
2
States / cities
Atlanta, Georgia • Decatur, Georgia
Source: ClinicalTrials.gov public record
Updated Jun 7, 2015 · Synced Sep 16, 2026, 2:36 PM EDT
Terminated Phase 2 Interventional Results available

Oral 6R-BH4 for the Treatment of Isolated Systolic Hypertension and Endothelial Dysfunction

NCT00802893
View directory record Official record
Conditions
Isolated Systolic Hypertension, Endothelial Dysfunction
Interventions
6R-BH4, Placebo
Drug · Other
Lead sponsor
Johns Hopkins University
Other
Eligibility
40 Years and older
Enrollment
3 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2008 – 2009
U.S. locations
1
States / cities
Baltimore, Maryland
Source: ClinicalTrials.gov public record
Updated Aug 20, 2017 · Synced Sep 16, 2026, 2:36 PM EDT
Completed Phase 1 Interventional

6R-BH4 Pulmonary Arterial Hypertension Study

NCT00435331
View directory record Official record
Conditions
Pulmonary Arterial Hypertension
Interventions
sapropterin dihydrochloride (6R-BH4)
Drug
Lead sponsor
Vanderbilt University
Other
Eligibility
18 Years and older
Enrollment
14 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2008
U.S. locations
1
States / cities
Nashville, Tennessee
Source: ClinicalTrials.gov public record
Updated Jun 18, 2013 · Synced Sep 16, 2026, 2:36 PM EDT
Withdrawn Not applicable Interventional

Neuroimaging and Neurocognitive Assessment and Response to Sapropterin Dihydrochloride Treatment in Phenylketonuria

NCT01412437
View directory record Official record
Conditions
PKU
Interventions
diet, sapropterin dihydrochloride
Dietary Supplement · Drug
Lead sponsor
Children's National Research Institute
Other
Eligibility
18 Years to 40 Years
Healthy volunteers
Healthy volunteers not accepted
Timeline
2011 – 2012
U.S. locations
1
States / cities
Washington D.C., District of Columbia
Source: ClinicalTrials.gov public record
Updated Dec 16, 2014 · Synced Sep 16, 2026, 2:36 PM EDT