Suspended

The Effects of 5-hydroxytryptophan (5-HTP) and L-3,4-dihydroxyphenylalanine (L-DOPA) Supplementation on Central Nervous System Excitability and Motor Function in Individuals With Spinal Cord Injury

What is being tested

5HTP

+ L-DOPA

+ Placebo oral tablet

Drug

Who is being recruted

Central Nervous System Diseases+3

+ Nervous System Diseases

+ Spinal Cord Diseases

From 18 to 65 Years

See all eligibility criteria

How is the trial designed

Basic Science Study

Placebo-ControlledPhase 2 & 3

Interventional

Study Start: June 2019

See protocol details

Summary

Principal SponsorJessica M D'Amico

Last updated: January 28, 2026

Sourced from a government-validated database.Claim as a partner

Study start date: June 19, 2019

Actual date on which the first participant was enrolled.

This study will examine whether supplementation with the serotonin and dopamine precursors, 5HTP and L-DOPA can alter central nervous system excitability and improve motor function after incomplete and complete spinal cord injuries.

Official TitleThe Effects of 5-hydroxytryptophan (5-HTP) and L-3,4-dihydroxyphenylalanine (L-DOPA) Supplementation on Central Nervous System Excitability and Motor Function in Individuals With Spinal Cord Injury

NCT04000919

Principal SponsorJessica M D'Amico

Last updated: January 28, 2026

Sourced from a government-validated database.Claim as a partner

Protocol

This section provides details of the study plan, including how the study is designed and what the study is measuring.

Design Details

30 patients to be enrolled

Total number of participants that the clinical trial aims to recruit.

Basic Science Study

Basic science studies help researchers understand how the body works or how a disease develops. They don't test treatments, but they build the foundation for future therapies.

Eligibility

Researchers look for people who fit a certain description, called eligibility criteria: person's general health condition or prior treatments.

Conditions

Criteria

Any sex

Biological sex of participants that are eligible to enroll.

From 18 to 65 Years

Range of ages for which participants are eligible to join.

Healthy volunteers not allowed

If individuals who are healthy and do not have the condition being studied can participate.

Conditions

Pathology

Central Nervous System DiseasesNervous System DiseasesSpinal Cord DiseasesSpinal Cord InjuriesWounds and InjuriesTrauma, Nervous System

Criteria

Inclusion Criteria: * Individuals aged 18-65 years of age. * Patients must have suffered a trauma to the spinal cord at least 1 year ago or longer. * Patients must exhibit some degree of spasticity which can be self-reported (Penn spasm frequency) or if assessed by a physiotherapist, a modified Ashworth spasticity score greater than 1 Exclusion Criteria: * Individuals with damage to the nervous system other than to the spinal cord * Pregnant or breastfeeding women * Alcoholic patients * Patients with a history of seizures or epilepsy * Patients with a history of suicidal thoughts or behaviors * Patients with active or inactive implants including cardiac pacemakers, implantable defibrillators, ocular implants, deep brain stimulators, vagus nerve stimulator, and implanted medication pumps * Patients with conductive, ferromagnetic or other magnetic-sensitive metals implanted in their head * Patients with: * Known or suspected allergy to the medication or the ingredients * Cardiovascular disease including history of heart attack or heart rhythm irregularities * Coronary artery disease * Comatose or depressed states due to CNS depressants * Endocrine dysfunction * Blood dyscrasias * Bone marrow depression * History of seizures * Hypocalcemia * History of stomach ulcers * Wide-angle glaucoma * Phenylketonuria Patients taking: * Monoamine oxidase inhibitor therapy * Serotonergic antidepressants: selective serotonin and norepinephrine reuptake inhibitors * Tricyclic antidepressants * Any type of serotonergic agonist * Dopamine D2 receptor antagonists * Amphetamine * CNS depressants * Levodopa * Lithium * Anti-hypertensive drugs (Carbidopa and L-DOPA) * Iron salts * Metoclopramide * Phenothiazine medication

Study Plan

Find out more about all the medication administered in this study, their detailed description and what they involve.

Treatment Groups

Study Objectives

4 intervention groups are designated in this study

50% chance of being blinded to the placebo group

Treatment Groups

Group I

Active Comparator

During one of the four occasions participants visit the lab they will receive 5HTP combined with carbidopa (50-200mg HTP/50mg carbidopa). Neurophysiology outcome measures will be obtained at 30, 60, 90, 120 and 150 min post drug-intake.

Group II

Active Comparator

During one of the four occasions participants visit the lab they will receive L-DOPA combined with carbidopa (50-200mg L-DOPA/50mg carbidopa). Neurophysiology outcome measures will be obtained at 30, 60, 90, 120 and 150 min post drug-intake.

Group III

Placebo

Participants will visit the lab and on one of four different occasions and will receive a placebo. Neurophysiology outcome measures will be obtained at 30, 60, 90, 120 and 150 min post drug-intake.

Group IV

Sham

Participants will visit the lab and on one of four different occasions they will receive carbidopa only (50 mg). Neurophysiology outcome measures will be obtained at 30, 60, 90, 120 and 150 min post drug-intake.

Study Objectives

Primary Objectives

Secondary Objectives

Study Centers

These are the hospitals, clinics, or research facilities where the trial is being conducted. You can find the location closest to you and its status.

This study has 1 location

Suspended

University of Louisville, Kentucky Spinal Cord Injury Research Centre

Louisville, United StatesOpen University of Louisville, Kentucky Spinal Cord Injury Research Centre in Google Maps

SuspendedOne Study Center