COMT Inhibition Among Individuals With Comorbid AUD/ADHD

COMT Inhibition as a Potential Therapeutic Target Among Individuals With Comorbid Alcohol Use Disorder and Attention-Deficit/Hyperactivity Disorder

COMT Inhibition Among Individuals With Comorbid AUD/ADHD (NCT03904498) is a Phase 2 interventional studying Alcohol Use Disorder and Attention Deficit Hyperactivity Disorder, sponsored by University of Colorado, Denver. RECRUITING as of the most recent ClinicalTrials.gov update. Talk to your doctor before contacting the trial site.

About This Trial

What Stage of Research Is This?

Phase 2 trials evaluate whether a treatment actually works against Alcohol Use Disorder and continue monitoring side effects. Phase 2 enrolls larger groups (typically 100–300 patients) and produces the first real efficacy signal. A successful Phase 2 readout is what unlocks the much larger Phase 3 confirmatory trials needed for FDA approval.

This trial is currently recruiting participants. The sponsor has registered the study with ClinicalTrials.gov as actively enrolling, which means new applicants who meet the eligibility criteria can be considered for screening. Trial status can change between updates — confirm current recruiting status with the study contact before traveling for a screening visit.

Target enrollment of 62 participants puts this in the typical range for a Phase 2-style efficacy study or a moderate Phase 3 trial in a focused Alcohol Use Disorder subpopulation. At this scale, the study has enough statistical power to detect a clear treatment effect but is not the largest cohort in the field.

Who May Be Eligible (Plain English)

Who May Qualify: 1. Age 21-65. 2. Meets Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) criteria for current Alcohol Use Disorder (AUD) and current Attention-Deficit/Hyperactivity Disorder (ADHD), as assessed by the Structured Clinical Interview for DSM-5 (SCID-5) or WHO-ASRS. 3. Currently not engaged in, and does not want treatment for, AUD or ADHD. 4. Currently not taking any medication for AUD or ADHD. 5. Able to read and understand questionnaires and willing to sign a consent form. 6. Lives within 50 miles of the study site. Who Should NOT Join This Trial: 1. Current DSM-5 diagnosis of any other substance use disorder except Nicotine Use Disorder. 2. Any psychoactive substance use (except nicotine) within the last 30 days, as indicated by self-report and urine drug screen (UDS) 3. Current DSM-5 psychotic, mood, anxiety, obsessive-compulsive, trauma-related, or eating disorder, as assessed by SCID-5. 4. Current suicidal ideation or homicidal ideation. 5. Current use of any psychoactive medication, as evidenced by self-report and UDS. 6. History of severe alcohol withdrawal (e.g., seizure, delirium tremens), as evidenced by self-report and assessment with Clinical Institute Withdrawal Assessment for Alcohol-Revised (CIWA-Ar). 7. Clinically significant medical problems such as cardiovascular, renal, gastrointestinal, or endocrine problems, as evidenced by medical history and physical exam. 8. Past alcohol-related medical illness, such as gastrointestinal bleeding, pancreatitis, or peptic ulcer. 9. Current or past hepatocellular disease, as indicated by verbal report, or elevations of alanine aminotransferase (ALT) or aspartate aminotransferase (AST) greater than the upper limit of the normal range at screening. 10. Females of childbearing potential who are pregnant (by plasma HCG), nursing, or who are not using a reliable form of contraception. 11. Current charges pending for a violent crime (not including DUI-related offenses). ...See full criteria on ClinicalTrials.gov Always talk to your doctor about whether this trial is right for you.

These are translations of the protocol\'s inclusion and exclusion criteria, simplified for patients and caregivers. The original clinical text appears below. Eligibility is ultimately confirmed by the trial site\'s screening process — this summary is a starting point for a conversation with your doctor, not a final determination.

Original Eligibility Criteria

View original clinical language

Inclusion Criteria: 1. Age 21-65. 2. Meets Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) criteria for current Alcohol Use Disorder (AUD) and current Attention-Deficit/Hyperactivity Disorder (ADHD), as assessed by the Structured Clinical Interview for DSM-5 (SCID-5) or WHO-ASRS. 3. Currently not engaged in, and does not want treatment for, AUD or ADHD. 4. Currently not taking any medication for AUD or ADHD. 5. Able to read and understand questionnaires and informed consent. 6. Lives within 50 miles of the study site. Exclusion Criteria: 1. Current DSM-5 diagnosis of any other substance use disorder except Nicotine Use Disorder. 2. Any psychoactive substance use (except nicotine) within the last 30 days, as indicated by self-report and urine drug screen (UDS) 3. Current DSM-5 psychotic, mood, anxiety, obsessive-compulsive, trauma-related, or eating disorder, as assessed by SCID-5. 4. Current suicidal ideation or homicidal ideation. 5. Current use of any psychoactive medication, as evidenced by self-report and UDS. 6. History of severe alcohol withdrawal (e.g., seizure, delirium tremens), as evidenced by self-report and assessment with Clinical Institute Withdrawal Assessment for Alcohol-Revised (CIWA-Ar). 7. Clinically significant medical problems such as cardiovascular, renal, gastrointestinal, or endocrine problems, as evidenced by medical history and physical exam. 8. Past alcohol-related medical illness, such as gastrointestinal bleeding, pancreatitis, or peptic ulcer. 9. Current or past hepatocellular disease, as indicated by verbal report, or elevations of alanine aminotransferase (ALT) or aspartate aminotransferase (AST) greater than the upper limit of the normal range at screening. 10. Females of childbearing potential who are pregnant (by plasma HCG), nursing, or who are not using a reliable form of contraception. 11. Current charges pending for a violent crime (not including DUI-related offenses). 12. Lack of a stable living situation. 13. Presence of ferrous metal in the body, as evidenced by metal screening and self-report. 14. Severe claustrophobia or morbid obesity that preclude placement in the MRI scanner. 15. History of neurological disease or head injury with \> 2 minutes of unconsciousness.

Treatments Being Tested

DRUG

Tolcapone

Tolcapone 100 mg tablets

DRUG

Placebo

Placebo tablets

Locations (1)

Trial sites listed on ClinicalTrials.gov for this study. Site activation status can vary — confirm with the specific site before traveling for a screening visit.

University of Colorado Anschutz Medical Campus

Aurora, Colorado, United States

How to Talk to Your Doctor About This Trial

Bring the printable summary of this trial — including the NCT ID (NCT03904498), the sponsor (University of Colorado, Denver), and the key eligibility criteria — to your next appointment. Your doctor can review the inclusion and exclusion criteria against your medical history, lab values, and current treatments to assess whether you are likely to qualify. They can also help you weigh whether trial participation makes sense alongside your existing care plan.

Useful questions to walk through together: What does the trial protocol require beyond standard care? How long is the active treatment phase, and how long is follow-up? Are there study visits at sites I can reach? Who pays for the trial-specific procedures, and who pays for standard-of-care portions? See our 25 questions to ask about clinical trials guide for a more complete checklist.

Authoritative Sources

The official record for this trial lives on ClinicalTrials.gov — the federal registry maintained by the National Library of Medicine at NIH. For background on how this trial fits into the FDA approval pathway, see the FDA drug approval process. For oncology-specific guidance for patients considering trials, the National Cancer Institute publishes patient-oriented overviews. International trial registries are aggregated by the WHO ICTRP.

Frequently Asked Questions

What is the NCT03904498 clinical trial studying?

The purpose of this study is to determine whether the catechol-O-methyltransferase (COMT) inhibitor tolcapone, relative to placebo, affects response to alcohol, decision-making, brain activation associated with alcohol cue reactivity, response inhibition, and selective attention, or alcohol drinking. The full protocol is registered on ClinicalTrials.gov and includes the primary outcome measures, eligibility criteria, and study endpoints.

Who can participate in NCT03904498?

Eligibility for this trial depends on the specific inclusion and exclusion criteria set by the sponsor. The plain-English summary above translates the most important criteria into accessible language; the official clinical text is preserved in the collapsible section underneath. Whether you fit any specific trial is a medical decision your doctor needs to confirm — bring the trial information to your treating physician for a full review against your medical history.

How do I contact the trial site for NCT03904498?

Contact information registered with ClinicalTrials.gov is shown in the sidebar of this page. Before reaching out, confirm with your treating physician that this trial is appropriate for your situation. The trial site will then walk you through the screening process to determine final eligibility.

Is participating in a clinical trial safe?

Clinical trials in the United States are regulated by the FDA and overseen by Institutional Review Boards (IRBs) that review the protocol for safety. Risk varies by trial — Phase 1 studies test new treatments in humans for the first time, while Phase 3 trials use treatments that have already passed earlier safety screening. The informed consent document for any specific trial details the known risks and what to expect. Discuss those risks with your physician before deciding whether to participate.

Where can I verify the data on this page?

Every detail on this page comes directly from the ClinicalTrials.gov API. Click "View on ClinicalTrials.gov" in the sidebar to see the official, unmodified record. The federal record is always authoritative; this page is a structured presentation with a plain-English eligibility translation. For background on how clinical trials are regulated, see the FDA drug approval process documentation.

How This Page Is Built

Every field on this page is pulled directly from the ClinicalTrials.gov API v2 — no estimates, no proxies. The plain-English eligibility translation is generated from the original protocol text and reviewed for fidelity to the underlying clinical criteria. The original clinical text remains visible in the collapsible section above so users and clinicians can verify the translation. Read the full methodology for the data pipeline and known limitations.

Source: ClinicalTrials.gov API v2 record for NCT03904498. Maintained by the National Library of Medicine at NIH. Public domain. Cite as: "TrialFinderData. NCT03904498. Data: ClinicalTrials.gov."

Medical disclaimer: This page is informational, not medical advice. Talk to your doctor about whether a clinical trial is right for you.

Last updated 2026-05-08 · Data from ClinicalTrials.gov.