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Showing 1–24 of 33 matching trials from the live ClinicalTrials.gov search.
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Filters: Intervention: 6R BH4 Clear all
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 6, 2026, 3:33 AM EDT
Completed Phase 2 Interventional Results available

A Phase 2 Study of the Effects of Sapropterin Dihydrochloride on Symptomatic Peripheral Arterial Disease

NCT00403494
View directory record Official record
Conditions
Intermittent Claudication
Interventions
Placebo, Sapropterin Dihydrochloride
Other · Drug
Lead sponsor
BioMarin Pharmaceutical
Industry
Eligibility
40 Years to 80 Years
Enrollment
190 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2006 – 2009
U.S. locations
17
States / cities
Scottsdale, Arizona • Sacramento, California • San Diego, California + 14 more
Source: ClinicalTrials.gov public record
Updated Jan 6, 2021 · Synced Sep 6, 2026, 3:33 AM EDT
Completed Phase 2 Interventional Results available

Tetrahydrobiopterin in Patients With Chronic Kidney Disease (CKD) and Albuminuria

NCT00625820
View directory record Official record
Conditions
Kidney Disease, Albuminuria
Interventions
6R BH4, Vitamin C
Drug · Dietary Supplement
Lead sponsor
University of Michigan
Other
Eligibility
18 Years to 75 Years
Enrollment
17 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2008
U.S. locations
1
States / cities
Ann Arbor, Michigan
Source: ClinicalTrials.gov public record
Updated Oct 17, 2016 · Synced Sep 6, 2026, 3:33 AM EDT
Completed Phase 4 Interventional Results available

The Effectiveness of Kuvan in Amish PKU Patients

NCT02677870
View directory record Official record
Conditions
Phenylketonuria
Interventions
saproterin dihydrochloride, Diet treatment
Drug · Other
Lead sponsor
University Hospitals Cleveland Medical Center
Other
Eligibility
2 Years to 60 Years
Enrollment
7 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2018 – 2019
U.S. locations
1
States / cities
Cleveland, Ohio
Source: ClinicalTrials.gov public record
Updated Apr 26, 2022 · Synced Sep 6, 2026, 3:33 AM 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 6, 2026, 3:33 AM 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 6, 2026, 3:33 AM 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 6, 2026, 3:33 AM EDT
Withdrawn Phase 1 Interventional Accepts healthy volunteers

O2 Transport and Utilization in Health and Lung Disease

NCT04014712
View directory record Official record
Conditions
COPD, Tetrahydrobiopterin Deficiency, Oxidative Stress
Interventions
Tetrahydrobiopterin, Placebo oral tablet
Drug
Lead sponsor
University of Massachusetts, Amherst
Other
Eligibility
18 Years to 85 Years
Healthy volunteers
Accepts healthy volunteers
Timeline
2021 – 2022
U.S. locations
1
States / cities
Amherst, Massachusetts
Source: ClinicalTrials.gov public record
Updated Dec 18, 2023 · Synced Sep 6, 2026, 3:33 AM 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 6, 2026, 3:33 AM EDT
Completed Phase 2 Interventional

A Study of the Effects of 6R-BH4 on Blood Pressure in Subjects With Poorly Controlled Systemic Hypertension

NCT00325962
View directory record Official record
Conditions
Hypertension
Interventions
6R-BH4 (sapropterin dihydrochloride)
Drug
Lead sponsor
BioMarin Pharmaceutical
Industry
Eligibility
18 Years and older
Enrollment
84 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2006 – 2008
U.S. locations
24
States / cities
Hoover, Alabama • Huntsville, Alabama • Mobile, Alabama + 21 more
Source: ClinicalTrials.gov public record
Updated Jul 20, 2009 · Synced Sep 6, 2026, 3:33 AM EDT
Completed Phase 2 Interventional Results available

Safety and Efficacy Study of Phenoptin in Subjects With Hyperphenylalaninemia Due to BH4 Deficiency

NCT00355264
View directory record Official record
Conditions
Tetrahydrobiopterin Deficiencies, Hyperphenylalaninemia, Non-Phenylketonuric
Interventions
Phenoptin
Drug
Lead sponsor
BioMarin Pharmaceutical
Industry
Eligibility
Not listed
Enrollment
12 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2006 – 2009
U.S. locations
9
States / cities
Los Angeles, California • Chicago, Illinois • Minneapolis, Minnesota + 6 more
Source: ClinicalTrials.gov public record
Updated Sep 24, 2020 · Synced Sep 6, 2026, 3:33 AM EDT
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 6, 2026, 3:33 AM EDT
Completed Phase 2 Interventional Accepts healthy volunteers Results available

Cystic Fibrosis and Endothelial Function: At Rest and During Exercise

NCT01772758
View directory record Official record
Conditions
Cystic Fibrosis
Interventions
BH4 5mg, BH4 20mg, Antioxidant Cocktail
Drug · Dietary Supplement
Lead sponsor
Augusta University
Other
Eligibility
7 Years and older
Enrollment
64 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2011 – 2016
U.S. locations
1
States / cities
Augusta, Georgia
Source: ClinicalTrials.gov public record
Updated Jun 19, 2019 · Synced Sep 6, 2026, 3:33 AM 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 6, 2026, 3:33 AM 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 6, 2026, 3:33 AM 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 6, 2026, 3:33 AM EDT
Completed Phase 3 Interventional Results available

Study to Evaluate the Safety and Efficacy of Phenoptin™ in Subjects With Phenylketonuria Who Have Elevated Phenylalanine Levels

NCT00104247
View directory record Official record
Conditions
Phenylketonurias
Interventions
sapropterin dihydrochloride, 6R-BH4, tetrahydrobiopterin
Drug
Lead sponsor
BioMarin Pharmaceutical
Industry
Eligibility
8 Years and older
Enrollment
89 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2005 – 2006
U.S. locations
13
States / cities
Los Angeles, California • Oakland, California • New Haven, Connecticut + 10 more
Source: ClinicalTrials.gov public record
Updated Jul 22, 2014 · Synced Sep 6, 2026, 3:33 AM EDT
Terminated Phase 1 Interventional Accepts healthy volunteers

Response to Phenylketonuria to Tetrahydrobiopterin (BH4)

NCT00244218
View directory record Official record
Conditions
Phenylketonuria
Interventions
tetrahydrobiopterin (BH4)
Drug
Lead sponsor
The University of Texas Medical Branch, Galveston
Other
Eligibility
10 Years and older
Enrollment
57 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2005 – 2015
U.S. locations
1
States / cities
Galveston, Texas
Source: ClinicalTrials.gov public record
Updated Sep 20, 2021 · Synced Sep 6, 2026, 3:33 AM EDT
Completed Not applicable Interventional Results available

Fluorodeoxyglucose Positron Emission Tomography (FDG PET) Findings in Patients With Phenylketonuria Before and After KUVAN Therapy

NCT00986973
View directory record Official record
Conditions
Phenylketonuria
Interventions
Sapropterin
Drug
Lead sponsor
Children's Hospital of Philadelphia
Other
Eligibility
18 Years to 50 Years
Enrollment
6 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2010 – 2011
U.S. locations
1
States / cities
Philadelphia, Pennsylvania
Source: ClinicalTrials.gov public record
Updated Jun 7, 2015 · Synced Sep 6, 2026, 3:33 AM EDT
Completed Phase 3 Interventional Results available

Effect of Kuvan on Neurocognitive Function, Blood Phenylalanine Level, Safety, and Pharmacokinetics in Children With PKU

NCT00838435
View directory record Official record
Conditions
Phenylketonuria
Interventions
sapropterin dihydrochloride
Drug
Lead sponsor
BioMarin Pharmaceutical
Industry
Eligibility
Up to 6 Years
Enrollment
95 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2009 – 2018
U.S. locations
12
States / cities
La Jolla, California • Orange, California • Tampa, Florida + 9 more
Source: ClinicalTrials.gov public record
Updated Dec 21, 2020 · Synced Sep 6, 2026, 3:33 AM 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 6, 2026, 3:33 AM EDT
Completed Not applicable Interventional Accepts healthy volunteers Results available

Nitric Oxide Bioavailability in Chronic Obstructive Pulmonary Disease (COPD)

NCT01398943
View directory record Official record
Conditions
Pulmonary Disease, Chronic Obstructive
Interventions
Tetrahydrobiopterin (BH4), Antioxidant Cocktail
Drug · Dietary Supplement
Lead sponsor
Augusta University
Other
Eligibility
18 Years and older
Enrollment
60 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2010 – 2015
U.S. locations
1
States / cities
Augusta, Georgia
Source: ClinicalTrials.gov public record
Updated Dec 10, 2017 · Synced Sep 6, 2026, 3:33 AM 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 6, 2026, 3:33 AM EDT
Completed Early Phase 1 Interventional

Exercise and NO in HFrEF

NCT03136029
View directory record Official record
Conditions
Heart Failure With Reduced Ejection Fraction
Interventions
Antioxidant, Tetrahydrobiopterin (BH4), Exercise training
Dietary Supplement · Other
Lead sponsor
VA Office of Research and Development
Federal
Eligibility
18 Years and older
Enrollment
68 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2018 – 2025
U.S. locations
1
States / cities
Salt Lake City, Utah
Source: ClinicalTrials.gov public record
Updated Aug 5, 2025 · Synced Sep 6, 2026, 3:33 AM EDT