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Showing 1–24 of 63 matching trials from the live ClinicalTrials.gov search.
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Filters: Intervention: L-Tryptophan Clear all
Completed No phase listed Observational

L-5-HTP-Related EMS

NCT00001918
View directory record Official record
Conditions
Eosinophilia-Myalgia Syndrome
Interventions
Not listed
Lead sponsor
National Institute of Mental Health (NIMH)
NIH
Eligibility
Not listed
Enrollment
20 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
1999 – 2000
U.S. locations
1
States / cities
Bethesda, Maryland
Source: ClinicalTrials.gov public record
Updated Mar 3, 2008 · Synced Sep 2, 2026, 4:42 PM EDT
Recruiting Not applicable Interventional

Daily Amino Acid Supplementation for People With Parkinson's Disease

NCT07115563
View directory record Official record
Conditions
Parkinson Disease (PD)
Interventions
Targeted Amino Acid Supplement, Control (placebo)
Dietary Supplement
Lead sponsor
Cristina Colon-Semenza
Other
Eligibility
50 Years to 90 Years
Enrollment
30 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2025 – 2027
U.S. locations
2
States / cities
Farmington, Connecticut • Storrs, Connecticut
Source: ClinicalTrials.gov public record
Updated Aug 12, 2026 · Synced Sep 2, 2026, 4:42 PM EDT
Completed No phase listed Observational

Investigating the Role of Serotonin in Emotional Processing Through the Use of Tryptophan Depletion

NCT00090831
View directory record Official record
Conditions
Healthy
Interventions
Not listed
Lead sponsor
National Institute of Mental Health (NIMH)
NIH
Eligibility
20 Years to 50 Years
Enrollment
91 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2004 – 2012
U.S. locations
1
States / cities
Bethesda, Maryland
Source: ClinicalTrials.gov public record
Updated Dec 2, 2019 · Synced Sep 2, 2026, 4:42 PM EDT
Not listed Early Phase 1 Interventional Accepts healthy volunteers

Role of Gastrointestinal Microbes on Digestion of Resistant Starch and Tryptophan Availability to Humans

NCT02974699
View directory record Official record
Conditions
Type II Diabetes
Interventions
Potato Starch (Bob's Red Mill), Pregelatinized Starch (Resource ThickenUp)
Dietary Supplement
Lead sponsor
Wayne State University
Other
Eligibility
18 Years to 65 Years
Enrollment
20 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
Started 2017
U.S. locations
1
States / cities
Detroit, Michigan
Source: ClinicalTrials.gov public record
Updated May 3, 2017 · Synced Sep 2, 2026, 4:42 PM EDT
Completed Early Phase 1 Interventional Accepts healthy volunteers

Dietary Intake of Tryptophan and Metformin Response

NCT02184832
View directory record Official record
Conditions
Metformin Response, Fasting Glucose, Tryptophan Concentration, Metformin Concentration, Diet Tolerability
Interventions
Metformin, Low tryptophan diet, High tryptophan diet
Drug · Other
Lead sponsor
Massachusetts General Hospital
Other
Eligibility
20 Years to 40 Years
Enrollment
20 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2014 – 2016
U.S. locations
1
States / cities
Boston, Massachusetts
Source: ClinicalTrials.gov public record
Updated Mar 15, 2016 · Synced Sep 2, 2026, 4:42 PM EDT
Recruiting Phase 2 Interventional

Stereotactic Body Radiation Therapy Plus Immediate or Delayed Androgen Receptor Pathway Inhibitor and Androgen Deprivation Therapy or Salvage Radiation Therapy for the Treatment of Prostate Cancer, DIVINE Trial

NCT06378866
View directory record Official record
Conditions
Recurrent Castration-Sensitive Prostate Carcinoma, Recurrent Prostate Cancer, Castration-resistant Prostate Cancer, Biochemically Recurrent Prostate Carcinoma
Interventions
Abiraterone, Apalutamide, Biospecimen Collection, Bone Scan, Computed Tomography, Darolutamide, Degarelix, Enzalutamide, Goserelin, Histrelin, Leuprolide, Magnetic Resonance Imaging, Patient Observation, Positron Emission Tomography, Prednisone, Questionnaire Administration, Relugolix, Stereotactic Body Radiation Therapy, Triptorelin, Radiation Therapy, Image-Guided Therapy
Drug · Procedure · Other + 1 more
Lead sponsor
Mayo Clinic
Other
Eligibility
18 Years and older · Male only
Enrollment
532 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2024 – 2031
U.S. locations
3
States / cities
Phoenix, Arizona • Jacksonville, Florida • Rochester, Minnesota
Source: ClinicalTrials.gov public record
Updated Jul 19, 2026 · Synced Sep 2, 2026, 4:42 PM EDT
Recruiting Not applicable Interventional Accepts healthy volunteers

Prandial Metabolic Phenotype in Adults

NCT05400733
View directory record Official record
Conditions
Protein Metabolism
Interventions
Total Amino Acids, Essential Amino Acids, Essential Amino Acids + Hydroxy-methylbutyric acid (HMB), Essential Amino Acids + Leucine, Essential Amino Acids High, Placebo Water
Dietary Supplement
Lead sponsor
Texas A&M University
Other
Eligibility
60 Years to 80 Years
Enrollment
50 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2022 – 2026
U.S. locations
1
States / cities
College Station, Texas
Source: ClinicalTrials.gov public record
Updated Sep 30, 2025 · Synced Sep 2, 2026, 4:42 PM EDT
Recruiting Phase 3 Interventional

Treating Prostate Cancer That Has Come Back After Surgery With Apalutamide and Targeted Radiation Based on PET Imaging

NCT04423211
View directory record Official record
Conditions
Biochemically Recurrent Prostate Carcinoma, Metastatic Prostate Carcinoma, Prostate Adenocarcinoma, Stage IVB Prostate Cancer AJCC v8
Interventions
3-Dimensional Conformal Radiation Therapy, Apalutamide, Computed Tomography, Degarelix, External Beam Radiation Therapy, Fluciclovine F18, Goserelin Acetate, Intensity-Modulated Proton Therapy, Intensity-Modulated Radiation Therapy, Leuprolide Acetate, Magnetic Resonance Imaging, Positron Emission Tomography, Quality-of-Life Assessment, Questionnaire Administration, Relugolix, Stereotactic Body Radiation Therapy, Triptorelin, Volume Modulated Arc Therapy
Radiation · Drug · Procedure + 1 more
Lead sponsor
ECOG-ACRIN Cancer Research Group
Network
Eligibility
18 Years and older · Male only
Enrollment
804 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2020 – 2032
U.S. locations
341
States / cities
Anchorage, Alaska • Fairbanks, Alaska • Phoenix, Arizona + 240 more
Source: ClinicalTrials.gov public record
Updated Aug 18, 2026 · Synced Sep 2, 2026, 4:42 PM EDT
Enrolling by invitation No phase listed Observational

Cannabis, Neuroinflammation, and Suicidal Ideation: A Supplemental Brain Imaging Study

NCT07222306
View directory record Official record
Conditions
PTSD, Suicidal Thoughts and Behaviors, PTSD Symptoms, Depressive Symptoms
Interventions
1-(2-[+F]fluoroethyl)-L-tryptophan
Drug
Lead sponsor
Wayne State University
Other
Eligibility
19 Years to 69 Years
Enrollment
100 participants
Timeline
2026 – 2030
U.S. locations
1
States / cities
Detroit, Michigan
Source: ClinicalTrials.gov public record
Updated Aug 5, 2026 · Synced Sep 2, 2026, 4:42 PM EDT
Completed Phase 1Phase 2 Interventional Results available

Study of IDO Inhibitor in Combination With Gemcitabine and Nab-Paclitaxel in Patients With Metastatic Pancreatic Cancer

NCT02077881
View directory record Official record
Conditions
Metastatic Pancreatic Adenocarcinoma, Metastatic Pancreatic Cancer
Interventions
Nab-Paclitaxel, Gemcitabine, Indoximod
Drug
Lead sponsor
NewLink Genetics Corporation
Industry
Eligibility
18 Years and older
Enrollment
157 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2014 – 2018
U.S. locations
11
States / cities
Palo Alto, California • Augusta, Georgia • Lexington, Kentucky + 8 more
Source: ClinicalTrials.gov public record
Updated Apr 2, 2026 · Synced Sep 2, 2026, 4:42 PM EDT
Completed Phase 2 Interventional Results available

AMT-PET in Monitoring Telotristat Etiprate Treatment in Participants With MetastaticNeuroendocrine Neoplasm

NCT03453489
View directory record Official record
Conditions
Carcinoid Syndrome, Metastatic Nonfunctional Well Differentiated Neuroendocrine Neoplasm
Interventions
Carbon C 11 Alpha-methyltryptophan, Laboratory Biomarker Analysis, Positron Emission Tomography, Telotristat Etiprate
Other · Procedure · Drug
Lead sponsor
Barbara Ann Karmanos Cancer Institute
Other
Eligibility
18 Years and older
Enrollment
4 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2018 – 2020
U.S. locations
1
States / cities
Detroit, Michigan
Source: ClinicalTrials.gov public record
Updated Apr 9, 2025 · Synced Sep 2, 2026, 4:42 PM EDT
Withdrawn No phase listed Observational

Pharmacogenomics in Pulmonary Arterial Hypertension

NCT00593905
View directory record Official record
Conditions
Pulmonary Arterial Hypertension, Pulmonary Hypertension, PAH WHO Group I
Interventions
Sitaxsentan, Bosentan, Ambrisentan
Drug
Lead sponsor
West Penn Allegheny Health System
Other
Eligibility
Not listed
Healthy volunteers
Healthy volunteers not accepted
Timeline
2005 – 2012
U.S. locations
1
States / cities
Pittsburgh, Pennsylvania
Source: ClinicalTrials.gov public record
Updated Dec 8, 2021 · Synced Sep 2, 2026, 4:42 PM EDT
Completed Phase 2 Interventional

Tryptophan and Behavior Therapy for Cocaine Abuse - 1

NCT00000324
View directory record Official record
Conditions
Cocaine-Related Disorders
Interventions
Tryptophan
Drug
Lead sponsor
National Institute on Drug Abuse (NIDA)
NIH
Eligibility
18 Years to 55 Years
Enrollment
200 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
1997 – 2001
U.S. locations
1
States / cities
Baltimore, Maryland
Source: ClinicalTrials.gov public record
Updated Jan 11, 2017 · Synced Sep 2, 2026, 4:42 PM EDT
Completed Not applicable Interventional Accepts healthy volunteers

Chronic Obstructive Pulmonary Disorder and Acute Exercise

NCT02780219
View directory record Official record
Conditions
Pulmonary Disease, Chronic Obstructive
Interventions
stable amino acid infusion, acute exercise with amino acid infusion, 24-hour post exercise amino acid infusion
Other
Lead sponsor
Texas A&M University
Other
Eligibility
45 Years and older
Enrollment
57 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2016 – 2020
U.S. locations
1
States / cities
College Station, Texas
Source: ClinicalTrials.gov public record
Updated Feb 2, 2025 · Synced Sep 2, 2026, 4:42 PM EDT
Recruiting Phase 2 Interventional

5-HTP and Creatine for Depression R33 Phase

NCT05895747
View directory record Official record
Conditions
Major Depressive Disorder
Interventions
Low Dose 5-hydroxytryptophan, High Dose 5-hydroxytryptophan, Low Dose Creatine Monohydrate, High Dose Creatine Monohydrate, Placebo
Drug
Lead sponsor
University of Utah
Other
Eligibility
18 Years to 65 Years
Enrollment
106 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2023 – 2027
U.S. locations
1
States / cities
Salt Lake City, Utah
Source: ClinicalTrials.gov public record
Updated Aug 26, 2026 · Synced Sep 2, 2026, 4:42 PM EDT
Recruiting Phase 3 Interventional

Standard Systemic Therapy With or Without Definitive Treatment in Treating Participants With Metastatic Prostate Cancer

NCT03678025
View directory record Official record
Conditions
Castration Levels of Testosterone, Metastatic Prostatic Adenocarcinoma, Stage IV Prostate Cancer AJCC v8, Stage IVA Prostate Cancer AJCC v8, Stage IVB Prostate Cancer AJCC v8
Interventions
Abiraterone, Bicalutamide, Degarelix, Docetaxel, Flutamide, Goserelin Acetate, Histrelin Acetate, Leuprolide Acetate, Nilutamide, Orchiectomy, Prednisone, Quality-of-Life Assessment, Radiation Therapy, Radical Prostatectomy, Triptorelin
Drug · Procedure · Other + 1 more
Lead sponsor
SWOG Cancer Research Network
Network
Eligibility
18 Years and older · Male only
Enrollment
1,273 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2018 – 2031
U.S. locations
334
States / cities
Gilbert, Arizona • Phoenix, Arizona • Scottsdale, Arizona + 253 more
Source: ClinicalTrials.gov public record
Updated Sep 10, 2025 · Synced Sep 2, 2026, 4:42 PM EDT
Completed Phase 1Phase 2 Interventional Results available

Vaccine Therapy and 1-MT in Treating Patients With Metastatic Breast Cancer

NCT01042535
View directory record Official record
Conditions
Male Breast Cancer, Recurrent Breast Cancer, Stage IV Breast Cancer, Unspecified Adult Solid Tumor, Protocol Specific
Interventions
adenovirus-p53 transduced dendritic cell (DC) vaccine, 1-methyl-d-tryptophan, Laboratory biomarker analysis
Biological · Drug · Other
Lead sponsor
H. Lee Moffitt Cancer Center and Research Institute
Other
Eligibility
18 Years and older
Enrollment
44 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2009 – 2018
U.S. locations
1
States / cities
Tampa, Florida
Source: ClinicalTrials.gov public record
Updated Apr 10, 2018 · Synced Sep 2, 2026, 4:42 PM EDT
Active, not recruiting Phase 3 Interventional

Two Studies for Patients With High Risk Prostate Cancer Testing Less Intense Treatment for Patients With a Low Gene Risk Score and Testing a More Intense Treatment for Patients With a High Gene Risk Score, The PREDICT-RT Trial

NCT04513717
View directory record Official record
Conditions
Prostate Adenocarcinoma, Stage III Prostate Cancer AJCC v8, Stage IVA Prostate Cancer AJCC v8
Interventions
Apalutamide, Bicalutamide, Biospecimen Collection, Bone Scan, Buserelin, Computed Tomography, Degarelix, Flutamide, Goserelin, Histrelin, Leuprolide, Magnetic Resonance Elastography, Positron Emission Tomography, Quality-of-Life Assessment, Questionnaire Administration, Radiation Therapy, Relugolix, Triptorelin
Drug · Procedure · Other + 1 more
Lead sponsor
NRG Oncology
Other
Eligibility
18 Years and older · Male only
Enrollment
2,753 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2021 – 2038
U.S. locations
594
States / cities
Fairbanks, Alaska • Gilbert, Arizona • Peoria, Arizona + 438 more
Source: ClinicalTrials.gov public record
Updated Aug 16, 2026 · Synced Sep 2, 2026, 4:42 PM EDT
Completed Phase 2Phase 3 Interventional Accepts healthy volunteers Results available

Tryptophan MRI in People With Schizophrenia and Healthy Controls

NCT02067975
View directory record Official record
Conditions
Schizophrenia
Interventions
Tryptophan, Placebo
Drug
Lead sponsor
University of Maryland, Baltimore
Other
Eligibility
18 Years to 55 Years
Enrollment
93 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2014 – 2019
U.S. locations
1
States / cities
Catonsville, Maryland
Source: ClinicalTrials.gov public record
Updated Jul 29, 2024 · Synced Sep 2, 2026, 4:42 PM EDT
Active, not recruiting Phase 3 Interventional

Two Studies for Patients With Unfavorable Intermediate Risk Prostate Cancer Testing Less Intense Treatment for Patients With a Low Gene Risk Score and Testing a More Intense Treatment for Patients With a Higher Gene Risk Score, The Guidance Trial

NCT05050084
View directory record Official record
Conditions
Prostate Adenocarcinoma
Interventions
Bicalutamide, Buserelin, Darolutamide, Degarelix, Flutamide, Goserelin, Histrelin, Leuprolide, Radiation Therapy, Relugolix, Triptorelin
Drug · Radiation
Lead sponsor
NRG Oncology
Other
Eligibility
18 Years and older · Male only
Enrollment
2,050 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2021 – 2031
U.S. locations
567
States / cities
Birmingham, Alabama • Gilbert, Arizona • Peoria, Arizona + 432 more
Source: ClinicalTrials.gov public record
Updated Aug 16, 2026 · Synced Sep 2, 2026, 4:42 PM EDT
Withdrawn Not applicable Interventional

Pilot Study: Combining Nutritional Supplements With Standard Antidepressant to Treat Depression.

NCT02223299
View directory record Official record
Conditions
Depression
Interventions
L-tyrosine, L-Tryptophan, deplin, Placebo A, Placebo B
Dietary Supplement · Drug · Other
Lead sponsor
John D. Dingell VA Medical Center
Federal
Eligibility
18 Years to 65 Years
Healthy volunteers
Healthy volunteers not accepted
Timeline
2015
U.S. locations
1
States / cities
Detroit, Michigan
Source: ClinicalTrials.gov public record
Updated Feb 20, 2020 · Synced Sep 2, 2026, 4:42 PM EDT
Completed Phase 2 Interventional Results available

Mechanistic Approach to Preventing Atrophy and Restoring Function in Older Adults

NCT02145949
View directory record Official record
Conditions
Muscle Atrophy, Quality of Life
Interventions
Essential Amino Acids (EAA), Placebo (Alanine)
Drug
Lead sponsor
University of Oregon
Other
Eligibility
50 Years to 80 Years
Enrollment
80 participants
Healthy volunteers
Healthy volunteers not accepted
Timeline
2014 – 2020
U.S. locations
2
States / cities
Eugene, Oregon
Source: ClinicalTrials.gov public record
Updated Jul 22, 2024 · Synced Sep 2, 2026, 4:42 PM EDT
Completed Not applicable Interventional Accepts healthy volunteers

Effects of Alpha-lactalbumin Intake on Metabolic and Cognitive Functions in Elderly

NCT02082418
View directory record Official record
Conditions
Mild Cognitive Impairment
Interventions
Alpha-lactalbumin, Whey, Casein
Dietary Supplement
Lead sponsor
Texas A&M University
Other
Eligibility
55 Years and older
Enrollment
59 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2014 – 2016
U.S. locations
1
States / cities
College Station, Texas
Source: ClinicalTrials.gov public record
Updated Sep 29, 2025 · Synced Sep 2, 2026, 4:42 PM EDT
Terminated Phase 4 Interventional Accepts healthy volunteers Results available

Placebo-controlled Trial of 5-hydroxytryptophan and Creatine for SSRI or SNRI Augmentation in Treatment Resistant Depression in Females

NCT02922725
View directory record Official record
Conditions
Major Depressive Disorder
Interventions
5-hydroxytryptophan and Creatine, Placebo control
Drug · Other
Lead sponsor
Brent Michael Kious, MD, PhD
Other
Eligibility
25 Years to 40 Years · Female only
Enrollment
32 participants
Healthy volunteers
Accepts healthy volunteers
Timeline
2016 – 2020
U.S. locations
1
States / cities
Salt Lake City, Utah
Source: ClinicalTrials.gov public record
Updated May 30, 2022 · Synced Sep 2, 2026, 4:42 PM EDT