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Showing 1–24 of 61 matching trials from the live ClinicalTrials.gov search.
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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 6, 2026, 10:03 AM 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 6, 2026, 10:03 AM EDT
Withdrawn Phase 2Phase 3 Interventional

Trial of Kuvan in Lesch-Nyhan Disease

NCT00935753
View directory record Official record
Conditions
Behavioral Manifestations of Lesch-Nyhan Disease
Interventions
sapropterin
Drug
Lead sponsor
University of California, San Diego
Other
Eligibility
4 Years and older
Healthy volunteers
Healthy volunteers not accepted
Timeline
2009 – 2010
U.S. locations
1
States / cities
San Diego, California
Source: ClinicalTrials.gov public record
Updated Aug 1, 2019 · Synced Sep 6, 2026, 10:03 AM 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 6, 2026, 10:03 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, 10:03 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, 10:03 AM EDT
Terminated Not applicable Interventional Accepts healthy volunteers Results available

Bone Mineral Density in Adults With Hyperphenylalaninemia on Kuvan Therapy

NCT01541397
View directory record Official record
Conditions
Hyperphenylalaninemia, Phenylketonuria
Interventions
Sapropterin
Drug
Lead sponsor
The University of Texas Health Science Center, Houston
Other
Eligibility
18 Years to 50 Years
Enrollment
6 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2011 – 2012
U.S. locations
1
States / cities
Houston, Texas
Source: ClinicalTrials.gov public record
Updated Jul 6, 2015 · Synced Sep 6, 2026, 10:03 AM 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 6, 2026, 10:03 AM EDT
Completed Not applicable Interventional Results available

Impact of KUVAN® on Gastric Relaxation in Women With Diabetic Gastroparesis.

NCT01135186
View directory record Official record
Conditions
Gastroparesis
Interventions
sapropterin dihydrochloride
Drug
Lead sponsor
Stanford University
Other
Eligibility
18 Years to 65 Years · Female only
Enrollment
9 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2010 – 2012
U.S. locations
1
States / cities
Stanford, California
Source: ClinicalTrials.gov public record
Updated Sep 9, 2019 · Synced Sep 6, 2026, 10:03 AM EDT
Completed Phase 4 Interventional Results available

Effects of Kuvan on Melatonin Secretion

NCT01617070
View directory record Official record
Conditions
Phenylketonuria (PKU)
Interventions
Kuvan, Large Neutral Amino Acid Therapy
Drug · Dietary Supplement
Lead sponsor
University of Southern California
Other
Eligibility
18 Years and older
Enrollment
10 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2012 – 2014
U.S. locations
1
States / cities
Los Angeles, California
Source: ClinicalTrials.gov public record
Updated Nov 17, 2016 · Synced Sep 6, 2026, 10:03 AM EDT
Completed No phase listed Observational Accepts healthy volunteers

Sapropterin in Individuals With Phenylketonuria

NCT00730080
View directory record Official record
Conditions
Phenylketonuria
Interventions
Sapropterin (Kuvan)
Drug
Lead sponsor
Washington University School of Medicine
Other
Eligibility
6 Years to 50 Years
Enrollment
45 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2008 – 2018
U.S. locations
1
States / cities
St Louis, Missouri
Source: ClinicalTrials.gov public record
Updated Jun 17, 2018 · Synced Sep 6, 2026, 10:03 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, 10:03 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, 10:03 AM EDT
Completed Phase 1 Interventional Accepts healthy volunteers

A Phase 1 Study to Evaluate Effects of Sapropterin Dihydrochloride on QTc Intervals in Healthy Adult Subjects

NCT00789568
View directory record Official record
Conditions
Phenylketonuria
Interventions
sapropterin dihydrochloride, Moxifloxacin, Moxifloxacin placebo
Drug
Lead sponsor
BioMarin Pharmaceutical
Industry
Eligibility
18 Years to 50 Years
Enrollment
56 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2008 – 2009
U.S. locations
1
States / cities
Fargo, North Dakota
Source: ClinicalTrials.gov public record
Updated Jul 22, 2021 · Synced Sep 6, 2026, 10:03 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, 10:03 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, 10:03 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, 10:03 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, 10:03 AM EDT
Completed No phase listed Observational Accepts healthy volunteers

PKU Skin Stripping

NCT04368624
View directory record Official record
Conditions
Phenylketonurias
Interventions
Skin Tape, Blood Draw
Other · Diagnostic Test
Lead sponsor
Children's Hospital Medical Center, Cincinnati
Other
Eligibility
Not listed
Enrollment
86 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2015 – 2021
U.S. locations
1
States / cities
Cincinnati, Ohio
Source: ClinicalTrials.gov public record
Updated Jul 27, 2021 · Synced Sep 6, 2026, 10:03 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, 10:03 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, 10:03 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, 10:03 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, 10:03 AM 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 6, 2026, 10:03 AM EDT