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Effects of 5HTP on the Injured Human Spinal Cord (5-HTP only)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
ClinicalTrials.gov Identifier: NCT04520178
Recruitment Status : Active, not recruiting
First Posted : August 20, 2020
Last Update Posted : October 17, 2022
Wings for Life
Information provided by (Responsible Party):
University of Alberta

Brief Summary:
This study will assess how the serotonin precursor, 5-HTP, alter nervous system excitability and motor function in individuals with spinal cord injuries of differing chronicity and severity. Participants will visit the lab on 4 separate occasions where they will be administered four different drugs in a randomized, double-blinded, placebo-controlled crossover design.

Condition or disease Intervention/treatment Phase
Spinal Cord Injuries Drug: 5-Hydroxytryptophan 100 MG Drug: 5-Hydroxytryptophan Drug: Carbidopa Drug: Placebo Phase 2 Phase 3

Detailed Description:

This study will assess for the first time the effects of 5-HTP on neural excitability utilizing a combination of neurophysiological and functional testing in subacute motor complete (AIS A/B), chronic motor complete (AIS A/B) and chronic incomplete (AIS C/D) SCI participants. To reduce peripheral side effects such as nausea, these supplements will be co-administered with carbidopa which inhibits the action of peripheral AADC, thereby ensuring that 5-HTP can effectively cross the blood brain barrier prior to being broken down. The neurophysiological outcomes will allow for the determination of the mechanistic actions of each pharmacological agent on different pathways/sites within the central nervous system in three different patient populations with varying degrees of lesion severity and will for the determination of whether increased Amino Acid Decarboxylase (AADC) expression and therefore the efficacy of this approach is correlated to lesion severity and/or chronicity. Importantly, the use of functional testing will allow for the determination of whether these often-reported neurophysiological changes translate to improvements in muscle activation patterns and kinematics during cycling.

The effects of 5-HTP will be assessed across three different participant groups: i) subacute (6 months-1 year) AIS A/B SCI individuals, ii) chronic (>2 years post injury) AIS A/B SCI individuals and iii) chronic AIS C/D SCI individuals.. In a placebo-controlled, randomized crossover design, participants will receive i) 50 mg 5HTP combined with 50 mg carbidopa, ii) 100 mg 5-HTP combined with 50 mg carbidopa, iii) 50 mg carbidopa only or iv) placebo. Ten participants will be recruited in each group. Participants will visit the lab on four separate occasions, separated by at least 72 hours.

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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 30 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double (Participant, Outcomes Assessor)
Primary Purpose: Basic Science
Official Title: Effects of the Serotonin Precursor, 5-hydroxytryptophan, in the Injured Human Spinal Cord
Actual Study Start Date : July 1, 2020
Estimated Primary Completion Date : June 30, 2023
Estimated Study Completion Date : June 30, 2024

Resource links provided by the National Library of Medicine

Arm Intervention/treatment
Active Comparator: Low-dose 5HTP
50mg 5-HTP in combination with 50mg carbidopa
Drug: 5-Hydroxytryptophan
50mg combined with 50mg carbidopa

Drug: Carbidopa

Active Comparator: High-dose 5HTP
100mg 5-HTP in combination with 50mg carbidopa
Drug: 5-Hydroxytryptophan 100 MG
100mg combined with 50mg carbidopa

Drug: Carbidopa

Sham Comparator: Carbidopa
50mg carbidopa only
Drug: Carbidopa

Placebo Comparator: Placebo
Placebo comparator
Drug: Placebo

Primary Outcome Measures :
  1. Change in motoneuron excitability [ Time Frame: Pre drug-intake, 30minutes, 60minutes, 90minutes and 120minutes post drug-intake ]
    F waves

  2. Change in spinal excitability [ Time Frame: Pre drug-intake, 30minutes, 60minutes, 90minutes and 120minutes post drug-intake ]
    H reflex

  3. Change in flexor reflex/spasms [ Time Frame: Pre drug-intake, 30minutes, 60minutes, 90minutes and 120minutes post drug-intake ]
    Cutaneomuscular reflex

  4. Change in functional movement performance [ Time Frame: Pre drug-intake, 120-150minutes post drug-intake ]
    Leg cycling task

Secondary Outcome Measures :
  1. Serum analysis of 5HIAA [ Time Frame: 90-120minutes post drug-intake ]
    5-HIAA (serum)

  2. Serum analysis of serotonin [ Time Frame: 90-120minutes post drug-intake ]
    5-HT (serum and whole blood), cortisol

  3. Serum analysis of cortisol [ Time Frame: 90-120minutes post drug-intake ]
    serum cortisol

  4. Whole blood analysis of Serotonin [ Time Frame: 90-120minutes post drug-intake ]
    Blood 5HT

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 65 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • participants must have suffered trauma to the spinal cord at least six months ago or longer

Exclusion Criteria:

  • individuals with damage to the nervous system other than to the spinal cord
  • pregnant and/or breastfeeding women
  • alcoholic participants
  • history of seizure/epilepsy
  • history of suicidal thoughts or behaviors
  • known or suspected allergy to the medication ingredients
  • cardiovascular disease including history of heart attack or heart rhythm irregularities
  • coronary artery disease
  • reduced liver function or disease
  • reduced kidney function or disease
  • lung disease
  • comatose or depressed states due to CNS depressants
  • endocrine dysfunction
  • blood dyscrasias or blood related disease
  • bone marrow depression
  • hypocalcemia
  • history of stomach ulcers
  • wide angle glaucoma
  • phenylketonuria
  • history of tumors
  • uncontrolled heart problems
  • unstable psychiatric or mental disorder

Participants taking:

  • monoamine oxidase inhibitor therapy
  • serotonergic antidepressants
  • tricyclic antidepressants
  • any type of serotonergic agonist
  • dopamine D2 receptor antagonists
  • amphetamine
  • CNS depressants
  • levodopa
  • lithium
  • anti-hypertensive drugs
  • iron salts
  • metoclopramide
  • phenothiazine medication

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT04520178

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United States, Kentucky
University of Louisville
Louisville, Kentucky, United States, 40292
Canada, Alberta
University of Alberta
Edmonton, Alberta, Canada, T6G-2E1
Sponsors and Collaborators
University of Alberta
Wings for Life
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Principal Investigator: Jessica D'Amico, PhD University of Alberta
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Responsible Party: University of Alberta
ClinicalTrials.gov Identifier: NCT04520178    
Other Study ID Numbers: Pro00119483
First Posted: August 20, 2020    Key Record Dates
Last Update Posted: October 17, 2022
Last Verified: October 2022

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Studies a U.S. FDA-regulated Drug Product: Yes
Studies a U.S. FDA-regulated Device Product: No
Additional relevant MeSH terms:
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Spinal Cord Injuries
Spinal Cord Diseases
Central Nervous System Diseases
Nervous System Diseases
Trauma, Nervous System
Wounds and Injuries
Antiparkinson Agents
Anti-Dyskinesia Agents
Dopamine Agents
Neurotransmitter Agents
Molecular Mechanisms of Pharmacological Action
Physiological Effects of Drugs
Aromatic Amino Acid Decarboxylase Inhibitors
Enzyme Inhibitors
Antidepressive Agents, Second-Generation
Antidepressive Agents
Psychotropic Drugs