Spinal Cord InjuriesPhase 2/35-HTP onlyNCT04520178
Effects of 5HTP on the Injured Human Spinal Cord
A Phase 2/3 study testing 5-Hydroxytryptophan 100 MG, 5-Hydroxytryptophan and Carbidopa in people with Spinal Cord Injuries, run by University of Alberta at 2 sites in 2 countries.
Trial 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. Read more about this study
- Who is it for?
- Ages 18 to 65 years
- Conditions the study is for
- Spinal Cord Injuries
- What is being tested?
- 5-Hydroxytryptophan 100 MG, 5-Hydroxytryptophan and Carbidopa
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 6 participants
- Where
- 2 sitesin 2 countries
- Study dates
- 1 Jul 2020to 30 Dec 2026
- Phase
- Phase 2/3
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- participants must have suffered trauma to the spinal cord at least six months ago or longer
Who cannot join
- 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
Show all 36Show fewer
- 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
Trial locations and contacts
2 sites in 2 countries.
2 sites in 2 countries
United States1 site
University of Louisville
Louisville, Kentucky, 40292
About this study
Official title: Effects of the Serotonin Precursor, 5-hydroxytryptophan, in the Injured Human Spinal Cord
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.
Read the 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.
- Conditions
- Spinal Cord Injuries
- Being tested
- 5-Hydroxytryptophan 100 MG, 5-Hydroxytryptophan, Carbidopa, Placebo
- Medical subject headings
- Spinal Cord Injuries
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
5-Hydroxytryptophan 100 MGDrug
100mg combined with 50mg carbidopa
5-HydroxytryptophanDrug
50mg combined with 50mg carbidopa
CarbidopaDrug
50mg
PlaceboDrug
Placebo
| Study group | Role | What they receive |
|---|---|---|
| Low-dose 5HTP | Active comparator | 50mg 5-HTP in combination with 50mg carbidopa Receives: Drug: 5-Hydroxytryptophan; Drug: Carbidopa |
| High-dose 5HTP | Active comparator | 100mg 5-HTP in combination with 50mg carbidopa Receives: Drug: 5-Hydroxytryptophan 100 MG; Drug: Carbidopa |
| Carbidopa | Sham comparator | 50mg carbidopa only Receives: Drug: Carbidopa |
| Placebo | Placebo comparator | Placebo comparator Receives: Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in motoneuron excitability
F waves
Measured: Pre drug-intake, 30minutes, 60minutes, 90minutes and 120minutes post drug-intake
Change in spinal excitability
H reflex
Measured: Pre drug-intake, 30minutes, 60minutes, 90minutes and 120minutes post drug-intake
Change in flexor reflex/spasms
Cutaneomuscular reflex
Measured: Pre drug-intake, 30minutes, 60minutes, 90minutes and 120minutes post drug-intake
Change in functional movement performance
Leg cycling task
Measured: Pre drug-intake, 120-150minutes post drug-intake
Secondary outcomes (4)
Serum analysis of 5HIAA (UofL Cohort only)
5-HIAA (serum)
Measured: 90-120minutes post drug-intake
Serum analysis of serotonin (UofL Cohort only)
5-HT (serum and whole blood), cortisol
Measured: 90-120minutes post drug-intake
Serum analysis of cortisol (UofL Cohort only)
serum cortisol
Measured: 90-120minutes post drug-intake
Whole blood analysis of Serotonin (UofL Cohort only)
Blood 5HT
Measured: 90-120minutes post drug-intake
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted20 Aug 2020
- Study start1 Jul 2020
- Primary completion13 May 2026
- Study completion30 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Spinal Cord InjuriesStudies of the same condition, open and under way.
- More trials run by University of AlbertaThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2/3
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind
- Who is masked
- Participant, Outcomes assessor
- Enrolment
- 6 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Alberta
- Sponsor type
- University, hospital or other
- Collaborators
- Wings for Life
- Responsible party
- Sponsor
- Investigators
- Jessica D'Amico, PhD, Principal investigator, University of Alberta
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04520178
- Sponsor's protocol ID
- Pro00119483/00125176
- Acronym
- 5-HTP only
- Status last verified
- Sep 2026
- First submitted
- 17 Aug 2020
- Last updated
- 16 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 16 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of the Serotonin Precursor, 5-hydroxytryptophan, in the Injured Human Spinal Cord
- ClinicalTrials.gov ID
- NCT04520178
- Acronym / sponsor ID
- 5-HTP only / Pro00119483/00125176
- Conditions
- Spinal Cord Injuries
- Phase
- Phase 2/3
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 6 participants (actual)
- Lead sponsor
- University of AlbertaUniversity, hospital or other
- Collaborators
- Wings for Life
- Study start
- 1 Jul 2020 (actual)
- Primary completion
- 13 May 2026 (actual)
- Study completion
- 30 Dec 2026 (estimated)
- First posted
- 20 Aug 2020 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
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.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (participant, outcomes assessor)
- Number of arms
- 4
| Arm | Type | Receives |
|---|---|---|
| Low-dose 5HTP | Active comparator | Drug: 5-Hydroxytryptophan, Drug: Carbidopa50mg 5-HTP in combination with 50mg carbidopa |
| High-dose 5HTP | Active comparator | Drug: 5-Hydroxytryptophan 100 MG, Drug: Carbidopa100mg 5-HTP in combination with 50mg carbidopa |
| Carbidopa | Sham comparator | Drug: Carbidopa50mg carbidopa only |
| Placebo | Placebo comparator | Drug: PlaceboPlacebo comparator |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (1 listed)
- participants must have suffered trauma to the spinal cord at least six months ago or longer
Key exclusion criteria (36 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| 5-Hydroxytryptophan 100 MG100mg combined with 50mg carbidopa | Drug | High-dose 5HTP |
| 5-Hydroxytryptophan50mg combined with 50mg carbidopa | Drug | Low-dose 5HTP |
| Carbidopa50mg | Drug | Carbidopa, High-dose 5HTP, Low-dose 5HTP |
| PlaceboPlacebo | Drug | Placebo |
Primary outcome
Change in motoneuron excitability
Time frame: Pre drug-intake, 30minutes, 60minutes, 90minutes and 120minutes post drug-intake
F waves
Change in spinal excitability
Time frame: Pre drug-intake, 30minutes, 60minutes, 90minutes and 120minutes post drug-intake
H reflex
Change in flexor reflex/spasms
Time frame: Pre drug-intake, 30minutes, 60minutes, 90minutes and 120minutes post drug-intake
Cutaneomuscular reflex
Change in functional movement performance
Time frame: Pre drug-intake, 120-150minutes post drug-intake
Leg cycling task
4 secondary outcomes
Serum analysis of 5HIAA (UofL Cohort only)
Time frame: 90-120minutes post drug-intake
Serum analysis of serotonin (UofL Cohort only)
Time frame: 90-120minutes post drug-intake
Serum analysis of cortisol (UofL Cohort only)
Time frame: 90-120minutes post drug-intake
Whole blood analysis of Serotonin (UofL Cohort only)
Time frame: 90-120minutes post drug-intake
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 16 Sep 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Jessica D'Amico, PhD principal investigator
University of Alberta
2 sites in 2 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2/3 study testing 5-Hydroxytryptophan 100 MG, 5-Hydroxytryptophan and Carbidopa in people with Spinal Cord Injuries, run by University of Alberta at 2 sites in 2 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 36 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 16 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in United States, Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this combined phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in motoneuron excitability (time frame: Pre drug-intake, 30minutes, 60minutes, 90minutes and 120minutes post drug-intake). The study lists 4 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 16 Sep 2026.