Dronabinol As an Adjunct for Reducing Pain (DARP)-Texas Children's Hospital

March 11, 2026 updated by: Christopher D. Verrico, Baylor College of Medicine

A Randomized, Double-Blind, Placebo-Controlled, Parallel Groups Study to Explore The Safety And Therapeutic Potential Of Cannabinoids As An Adjunct For Reducing Pain (Carp)- TCH

This exploratory, proof-of-concept study is a double-blind (participants and investigators will be blinded), placebo-controlled, randomized, two-arm clinical trial of Marinol [dronabinol, synthetic Δ9-tetrahydrocannabinol (THC)] for e endometriosis-associated chronic pelvic pain (endo-CPP) with a 2:1 allocation ratio. Up to 75 subjects will be enrolled in this pilot study and randomized to receive doses of THC (up to 30 mg/day), orally, over 8 weeks. This study will be conducted at a single site; it does not include any stratifications, and there is no interim analysis planned. Notably, the goal is to determine whether there is enough evidence of the safety of THC to support the development of later-phase clinical trials. Thus, detailed developmental plans are contingent on the outcomes of this study.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Withdrawn

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Endometriosis is a progressive, chronic inflammatory disorder that affects approximately 10% of women of reproductive age, with up to 70% to 90% of patients experiencing pelvic pain symptoms, thereby reducing their quality of life, and decreasing labor productivity. Current standard treatments for endometriosis-associated chronic pelvic pain (endo-CPP) include progestin-based hormonal treatments, such as combined oral contraceptive (OC) pills, gonadotropin-releasing hormone (GnRH) analogs, and laparoscopic surgeries. However, endo-CPP often persists even after laparoscopic excision of endometriosis lesions, indicating that controlling disease progression does not necessarily lead to pain relief. As pain is an important factor in endometriosis, optimal analgesia should be sought, which, to date, has primarily been treated with non-steroidal anti-inflammatory drugs (NSAIDs), metamizole, or, in extreme cases, opioids. However, the response to NSAIDs is often ineffective. Additionally, NSAIDs are associated with a higher risk of gastrointestinal bleeding. As for metamizole, agranulocytosis is the most notorious adverse event, along with metamizole-associated hepatotoxicity. Although opioids are generally not recommended for pain relief in women with endometriosis, opioid prescriptions have been identified for women diagnosed with endometriosis within the past year in the United States (As-Sanie S, 2021). Patients undergoing robotic surgery for endometriosis use over two times as many opioids postoperatively as patients without endometriosis and experience higher perceived postoperative pain. Women with endometriosis have a four-fold greater risk of chronic opioid use compared to those without endometriosis. Opioids are highly addictive, and the use of both synthetic and natural opioids can quickly result in dependence, which includes physical and/or psychological dependence, as well as opioid use disorder. Side effects of opioid medications are generally dose-dependent and include constipation, miosis, sedation, and respiratory depression. However, the efficacy of THC in endo-CPP remains uncertain.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.
  • Name: Xiaoming Guan, MD, OBGYN
  • Phone Number: 832-826-7464
  • Email: xiaoming@bcm.edu

Study Contact Backup

  • Name: Adetola Vaughan, MA Psychology
  • Phone Number: 226134 713-791-1414
  • Email: avaughan@bcm.edu

Study Locations

  • United States
    • Texas
      • Hosuton, Texas, United States, 77030
        • Baylor College of Medicine
      • Houston, Texas, United States, 77030
        • Michael E DeBakey VA Medical Center

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Provision of signed and dated informed consent form.
  2. Stated willingness to comply with all study procedures and availability for the duration of the study.
  3. Ability to take oral medication per protocol.
  4. Female, aged 18-64 years.
  5. Females aged ≥ 18 years clinically diagnosed with endometriosis meeting one of the following criteria: a. Patients with previous surgical confirmation of endometriosis and a high suspicion of recurrence b. Patients with imaging (MRI or ultrasonography) findings highly suggestive of endometriosis and confirmed after surgery.
  6. Has chronic endometriosis pain that has persisted at least 3 months and has resulted in pain as determined by the Endometriosis Health Profile Questionnaire (EHP-30).
  7. For females of reproductive potential: currently practicing an effective form of two types of birth control, which are defined as those, alone or in combination, that result in a low failure rate (i.e., less than 1% per year) when used consistently and correctly, for at least 1 month prior to screening and agrees to use such a method during study participation and for an additional 4 weeks after the end of study medication administration unless she is surgically sterile, partner is surgically sterile, or she is postmenopausal (one year): a. contraceptive sponge, b. patch, c. double barrier (diaphragm/spermicidal or condom/spermicidal), d. intrauterine contraceptive system, e etonogestrel implant, f. medroxyprogesterone acetate contraceptive injection, g. complete abstinence from sexual intercourse, and/or hormonal vaginal contraceptive ring.
  8. Patients using oral contraceptives, vaginal ring for contraception and/or management of endometriosis, can be included if both they and their primary provider agree to stopping their medication and transitioning to dronabinol (THC) as the primary treatment of endometriosis throughout the study period
  9. Agreement to adhere to Lifestyle Considerations (see section 5.3) throughout study duration.
  10. On a stable pain treatment (pharmacological or otherwise) for ≥3 months at the time of the screening and agree to refrain from adding new analgesic medications or increasing their current dose of analgesic medications for the duration of the study.
  11. Due to the inability to translate patient facing documents into various languages the investigators will only recruit English speaking participants

Exclusion Criteria:

  1. Current and unwilling to stop use of cannabis/marijuana and any other cannabinoids (CBD), including over the counter CBD products.
  2. Known allergic reactions to cannabis, CBD, THC, or components of the study interventions.
  3. Have Blood Urea Nitrogen or Creatinine levels outside the normal range, or other clinically significant laboratory abnormalities
  4. Current use of automated external defibrillator (AED)
  5. Chronic daily opioid use and any chronic pain or frequently reoccurring pain condition, other than endometriosis, that is treated with opioids for > 14 days per month
  6. Women with a BMI > 35 kg/m2
  7. Current use of barbiturates, benzodiazepines, ethanol, lithium, buspirone, muscle relaxants which in the opinion of the P.I. and/or the admitting clinician would preclude the safe and/or successful completion of the study.
  8. Current use of amphetamines, other sympathomimetic agents, atropine, amoxapine, scopolamine, antihistamines, other anticholinergic agents, amitriptyline, or desipramine, within 3 months of randomization
  9. Treatment with another investigational drug or other intervention within 3 months of the screening visit.
  10. Pregnancy, plans to become pregnant, or lactation.
  11. Any interventional pain procedures within 6 weeks prior to screening or at any point during study enrollment.
  12. Surgical intervention or introduction/increased dose of an opioid or analgesic regimen at any point during study enrollment
  13. Implanted spinal cord or dorsal root ganglion stimulator for pain treatment.
  14. Meets DSM-V criteria for a current major psychiatric illness, such as bipolar disorder, or psychosis which in the opinion of the P.I. and/or the admitting clinician would preclude the safe and/or successful completion of the study.
  15. Have a history of substance abuse or dependence which in the opinion of the P.I. and/or the admitting clinician would preclude the safe and/or successful completion of the study.
  16. Have an increased risk of suicide that necessitates inpatient treatment or warrants therapy excluded by the protocol, and/or current suicidal plan, per investigator clinical judgement, based on interview and defined on the Columbia Suicidality Severity Rating Scale (C-SSRS).
  17. Have a history of seizures which in the opinion of the P.I. and/or the admitting clinician would preclude the safe and/or successful completion of the study.
  18. Have uncontrolled renal, hepatic, or other systemic disorders that in the opinion of the clinician may jeopardize the patient's safe participation in this study.
  19. Have a history of cardiac disorders which in the opinion of the P.I. and/or the admitting clinician would preclude the safe and/or successful completion of the study.
  20. Myocardial infarction or stroke in the previous 6 months.
  21. Resting heart rate of > 120 or Systolic blood pressure > 140 mm Hg, or diastolic blood pressure > 90 mm Hg.
  22. Any uncontrolled communicable disease (e.g., HIV/AIDS, tuberculosis, COVID, etc.) which in the opinion of the P.I. and/or the admitting clinician would preclude the safe and/or successful completion of the study.
  23. Have any other illness, condition, or use of medications, which in the opinion of the P.I. and/or the admitting clinician would preclude the safe and/or successful completion of the study.
  24. Have ECG abnormalities at screening including but not limited to bradycardia (less than 55 beats per minute); prolonged QTc interval (greater than 450 msec); Wolff-Parkinson White syndrome; wide complex tachycardia; 2nd degree, Mobitz type II heart block; 3rd degree heart block; left or right bundle branch block.
  25. Have chronic alcohol use (defined as greater then 3 drinks per day, averaged over one week)
  26. Known history of or suspected breast cancer on screening physical exam
  27. Current use of a progestin-containing contraceptive implant

Study Plan

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

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Placebo Comparator: Placebo
Capsules with placebo (i.e., cellulose filler), twice per day for 8 weeks.
Drug: Placebo
Matching placebo will be prepared and administered in the same manner as the active medication. Titration will occur in a masked fashion such that individuals assigned to placebo undergo a similar perceived titration process.
Experimental: Dronabinol
Dronabinol capsules, over-encapsulated with filler to match the appearance of the placebo capsule, up to 15 mg, twice per day for 8 weeks.
Drug: Dronabinol Capsules
Eligible subjects will be randomized (2:1) to dronabinol or placebo, administered orally. The dose of dronabinol will be titrated such that on Day 1, subjects will take 2.5 mg, twice. On subsequent days patients may gradually increase the total number of doses, by one dose each day, as needed and tolerated until either the optimal dose is achieved, or the dose reaches 30 mg THC per day.
Other Names:
  • Marinol
  • delta-9-tetrahydrocannabinol

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Pain Intensity
Time Frame: Baseline to 8-weeks
For change in pain intensity from baseline to 8-weeks, the investigators will estimate the mean within each arm using the The Endometriosis Health Profile Questionnaire (EHP-30). 30 point scale ranging from 0 (Never) to 5 (Always).
Baseline to 8-weeks
Safety Analysis
Time Frame: Baseline to 8-weeks
AEs will be coded using the most recent version of the Medical Dictionary of Regulatory Activities (MedDRA) preferred terms and will be grouped by system, organ, and class (SOC) designation. The severity, frequency, and relationship of AEs to investigational product will be presented by preferred term by SOC grouping. Listings of each individual AE including start date, stop date, severity, relationship, outcome, and duration will be provided.
Baseline to 8-weeks

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Analgesic Use Log
Time Frame: Baseline to 8-weeks
Analgesic Use Change in Analgesic Use Log scores Day 1 to 56 Secondary analyses will use proper tests and appropriate statistical methods at a significance level of 0.05 (2-sided).
Baseline to 8-weeks
Patient-Reported Outcomes Measurement Information System (PROMIS-29)
Time Frame: Baseline to 8-weeks
The severity of pain will be assessed by the validated scale within the Patient-Reported Outcomes Measurement Information System (PROMIS) is a 29-item profile instrument that can be used to assess seven subscales of health quality of life (QOL) for each of 8 domains-this outcome measure reports one of the 7 domains, anxiety: Physical Function, Anxiety, Depression, Fatigue, Sleep Disturbance, Ability to Participate in Social Roles and Activities, Pain Interference, and Pain Intensity. Responses rage from 5 (Without any difficulty) to 0 (Unable to do) on the Physical Function item, 1 (Never) to 5 (Always) on Anxiety, Depression, Ability to Participate in Social Roles and Activities items, 1 (Not at all) to 5 (Very Much) on the Fatigue, Sleep Disturbance, and Pain Interference items, 0 (No pain) to 10 (Worst Pain Imaginable ) on the Pain Intensity.
Baseline to 8-weeks
Visual Pain Scale
Time Frame: Baseline to 8-weeks
The Faces Pain Scale, a visual analogue scale (VAS), is self-report measure of pain intensity on the widely accepted 0-to-10 metric.
Baseline to 8-weeks
Profile of Mood States (POMS questionnaire)
Time Frame: Baseline to 8-weeks
Changes in POMS . Scale range is 1 to 5 and describes how the participant feels at the time the assessment is administered. Scale of 1, the lowest score, describes a feeling of Not At All right now for the mood and the scale of 5 gives the highest score representing a feeling of Extremely for the mood.
Baseline to 8-weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Baylor College of Medicine

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Christopher Verrico, PhD in Pharmacology, Baylor College of Medicine

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
April 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
March 1, 2028

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 30, 2028

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
February 10, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 13, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
February 19, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
March 13, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 11, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
February 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • H-56181

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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