Buprenorphine Plus Baclofen to Increase Analgesia in Healthy Volunteers

December 16, 2025 updated by: Karen Cropsey, University of Alabama at Birmingham
To determine if baclofen will enhance buprenorphine analgesia for acute pain in healthy volunteers.

Study Overview

Status

Status

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

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

Abuse of opioids is a significant and growing problem in the United States. In the past two decades, opioid prescriptions have quadrupled while the age of heroin initiation has decreased, suggesting that more individuals are using opioids and transitioning to heroin and potent synthetic opioids than in the past. Further, fatal opioid overdose is now the leading cause of accidental death and is the 5th highest overall cause of mortality in the US. Engaging opioid users in opioid agonist treatments has been shown to lower rates of criminal behavior, lower rates of non-opioid drug use, and increase retention in drug treatment programs, while decreasing mortality and new HIV and hepatitis infections. However, a recent study noted that 68% of patients prescribed buprenorphine had poor medication adherence, which was associated with illicit opioid use. A Cochrane review concluded that buprenorphine was less effective at retaining patients in treatment relative to methadone. One reason for lower treatment retention may be the high comorbidity of opioid use disorder and chronic pain and/or opioid-induced hyperalgesia. Buprenorphine, as a partial mu agonist, provides lower analgesia but an improved safety profile relative to full agonists like methadone. Thus, enhancing the analgesic properties of buprenorphine will provide a safer alternative for opioid use disorder patients with chronic pain/hyperalgesia.

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

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
19

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
  • Phase 3

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: Karen L Cropsey, Psy.D.
  • Phone Number: 2059754204
  • Email: kcropsey@uab.edu

Study Contact Backup

  • Name: Keith Chichester, B.A.
  • Phone Number: 2059757809
  • Email: krc80@uab.edu

Study Locations

  • United States
    • Alabama
      • Birmingham, Alabama, United States, 35209
        • University of Alabama, Birmingham

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

14 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • 18 years or older
  • general good health
  • English speaking

Exclusion Criteria:

  • Pregnant or nursing
  • Opioid use disorder or any substance use disorder other than nicotine
  • Prescribed agonist treatment for opioid dependence or prescribed opioids for a medical condition
  • Prescribed naltrexone
  • Known sensitivity to buprenorphine, naloxone, or baclofen
  • Acute or chronic pain condition
  • Trouble breathing or a pulmonary condition
  • Prescribed benzodiazepines or daily use of benzodiazepines
  • Positive drug screen (positive cannabis result allowed)
  • Cognitive impairment or psychiatric disorder requiring treatment
  • Uncontrolled hypertension

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: None (Open Label)

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
Participants randomized to this arm will receive one dosage of Placebo as part of their second study appointment.
Drug: Placebos
Participants will receive placebo in combination with 0.3 mg of buprenorphine to examine analgesia in acute pain tasks.
Experimental: Baclofen 5mg
Participants randomized to this arm will receive one dosage of 5 mg of Baclofen as part of their second study appointment.
Drug: Baclofen 5 mg
Participants will receive 5mg of baclofen in combination with 0.3 mg of buprenorphine to examine analgesia in acute pain tasks.
Experimental: Baclofen 10mg
Participants randomized to this arm will receive one dosage of 10 mg of Baclofen as part of their second study appointment.
Drug: Baclofen 10mg
Participants will receive 10mg of baclofen in combination with 0.3 mg of buprenorphine to examine analgesia in acute pain tasks.

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 Threshold
Time Frame: Baseline
Pain threshold refers to the intensity at which a stimulus is first perceived as painful. Heat stimuli will be delivered using a computer-controlled thermal stimulation system with a 30 millimeter X 30 millimeter probe. From a baseline of 32 degrees Celsius, the probe temperature will increase at a rate of .5 degrees Celsius/second until the participant responds by pressing a button on a handheld device. For heat pain threshold, participants will be instructed to press the button when the sensation "first becomes painful" Pain rating scores will be reflected in scores of 0-100, 0 being the least amount of pain and 100 being the most amount of pain.
Baseline
Pain Threshold
Time Frame: 1.5 hours post-drug administration during session 2, occurs 7 ± 2 days after baseline visit
Pain threshold refers to the intensity at which a stimulus is first perceived as painful. Heat stimuli will be delivered using a computer-controlled thermal stimulation system with a 30 millimeter X 30 millimeter probe. From a baseline of 32 degrees Celsius, the probe temperature will increase at a rate of .5 degrees Celsius/second until the participant responds by pressing a button on a handheld device. For heat pain threshold, participants will be instructed to press the button when the sensation "first becomes painful" Pain rating scores will be reflected in scores of 0-100, 0 being the least amount of pain and 100 being the most amount of pain.
1.5 hours post-drug administration during session 2, occurs 7 ± 2 days after baseline visit
Pain Tolerance
Time Frame: Baseline
Pain tolerance refers to the maximum amount of pain produced by a stimulus that a person is able/willing to tolerate. Heat stimuli will again be delivered using the computer-controlled thermal stimulation system. From a baseline of 32 degrees Celsius, the probe temperature will increase at a rate of .5 degrees Celsius/second until the participant responds by pressing a button on a handheld device. For heat pain tolerance, participants will be instructed to press the button when they are "no longer willing to tolerate" the painful sensation. Pain rating scores will be reflected in scores of 0-100, 0 being the least amount of pain and 100 being the most amount of pain.
Baseline
Pain Tolerance
Time Frame: 1.5 hours post-drug administration during session 2, occurs 7 ± 2 days after baseline visit
Pain tolerance refers to the maximum amount of pain produced by a stimulus that a person is able/willing to tolerate. Heat stimuli will again be delivered using the computer-controlled thermal stimulation system. From a baseline of 32 degrees Celsius, the probe temperature will increase at a rate of .5 degrees Celsius/second until the participant responds by pressing a button on a handheld device. For heat pain tolerance, participants will be instructed to press the button when they are "no longer willing to tolerate" the painful sensation. Pain rating scores will be reflected in scores of 0-100, 0 being the least amount of pain and 100 being the most amount of pain.
1.5 hours post-drug administration during session 2, occurs 7 ± 2 days after baseline visit
Temporal Summation of Pain
Time Frame: Baseline
Temporal summation of pain refers to a form of endogenous pain facilitation characterized by the perception of increased pain despite constant or even reduced peripheral afferent input. Temporal summation is presumed to be the psychophysical manifestation of wind-up. Wind-up is a phenomenon where repetitive stimulation of C primary afferents at rates greater than 0.3 Hertz produces a slowly increasing response of second-order neurons in the spinal cord. Pain rating scores will be reflected in scores of 0-100, 0 being the least amount of pain and 100 being the most amount of pain.
Baseline
Temporal Summation of Pain
Time Frame: 1.5 hours post-drug administration during session 2, occurs 7 ± 2 days after baseline visit
Temporal summation of pain refers to a form of endogenous pain facilitation characterized by the perception of increased pain despite constant or even reduced peripheral afferent input. Temporal summation is presumed to be the psychophysical manifestation of wind-up. Wind-up is a phenomenon where repetitive stimulation of C primary afferents at rates greater than 0.3 Hertz produces a slowly increasing response of second-order neurons in the spinal cord. Pain rating scores will be reflected in scores of 0-100, 0 being the least amount of pain and 100 being the most amount of pain.
1.5 hours post-drug administration during session 2, occurs 7 ± 2 days after baseline visit
Conditioned Pain Modulation
Time Frame: Baseline
A routinely used quantitative sensory testing protocol for the measurement of endogenous pain inhibition is conditioned pain modulation, which refers to the reduction in pain from one stimulus (the test stimulus) produced by the application of a second pain stimulus at a remote body site (the conditioning stimulus). Conditioned pain modulation is believed to reflect the perceptual manifestation of diffuse noxious inhibitory controls, whereby ascending projections from one noxious stimulus activate supraspinal structures that trigger descending inhibitory projections to the dorsal horn. Pain rating scores for the test stimulus and the conditioning stimulus will be reflected in scores of 0-100, 0 being the least amount of pain and 100 being the most amount of pain. The conditioned pain modulation score is the difference between the two pain rating scores.
Baseline
Conditioned Pain Modulation
Time Frame: 1.5 hours post-drug administration during session 2, occurs 7 ± 2 days after baseline visit
A routinely used quantitative sensory testing protocol for the measurement of endogenous pain inhibition is conditioned pain modulation, which refers to the reduction in pain from one stimulus (the test stimulus) produced by the application of a second pain stimulus at a remote body site (the conditioning stimulus). Conditioned pain modulation is believed to reflect the perceptual manifestation of diffuse noxious inhibitory controls, whereby ascending projections from one noxious stimulus activate supraspinal structures that trigger descending inhibitory projections to the dorsal horn. Pain rating scores for the test stimulus and the conditioning stimulus will be reflected in scores of 0-100, 0 being the least amount of pain and 100 being the most amount of pain. The conditioned pain modulation score is the difference between the two pain rating scores.
1.5 hours post-drug administration during session 2, occurs 7 ± 2 days after baseline visit
Suprathreshold Pain Response
Time Frame: Baseline
Ratings of pain in response to discrete stimuli with intensities above the pain threshold detection/ patients provide an intensity rating using any number of a 0-100 scale whereby 0=no pain and 100= the most intense pain imaginable
Baseline
Suprathreshold Pain Response
Time Frame: 1.5 hours post-drug administration during session 2, occurs 7 ± 2 days after baseline visit
Ratings of pain in response to discrete stimuli with intensities above the pain threshold detection/ patients provide an intensity rating using any number of a 0-100 scale whereby 0=no pain and 100= the most intense pain imaginable
1.5 hours post-drug administration during session 2, occurs 7 ± 2 days after baseline visit

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
Opioid Symptom Checklist
Time Frame: 30 minutes post-drug administration during session 2, occurs 7 ± 2 days after baseline visit
Measures the amount and intensity of side effects after being administered an opioid. The measure consists of 14 questions about potential opioid symptoms, and each the severity of the symptom is rated on a scale from 0 to 4, with 0 reflecting not at all feeling or being bothered by the symptom and 4 reflecting being severely bothered by the symptom. The score is the sum of the 14 responses. The minimum value is 0 and the maximum value is 56.
30 minutes post-drug administration during session 2, occurs 7 ± 2 days after baseline visit
26-item Visual Analog Scale (VAS)
Time Frame: 30 minutes post-drug administration during session 2, occurs 7 ± 2 days after baseline visit
Measures subjective and physiological effects of a medication using mood states as well as questions about the dose of medication. The measure consists of 7 questions about potential drug effects, and each response is rated on a scale of 0 to 100, with 0 reflecting not at all feeling the effect and 100 reflecting very much feeling the effect. The score is the sum of the 7 responses. The minimum value is 0 and the maximum value is 700.
30 minutes post-drug administration during session 2, occurs 7 ± 2 days after baseline visit
Drug Effects Questionnaire-5
Time Frame: 30 minutes post-drug administration during session 2, occurs 7 ± 2 days after baseline visit
Measures subjective experiences of a drug. The measure consists of 5 questions about the participant's experience of the drug effects, and each response is rated on a scale of 0 to 100, with 0 reflecting not at all having an experience and 100 reflecting extremely having that experience. The score is the sum of the 5 responses. The minimum value is 0 and the maximum value is 500.
30 minutes post-drug administration during session 2, occurs 7 ± 2 days after baseline visit
26-item Visual Analog Scale ("Subjective Drug Effects")
Time Frame: 30 minutes post-drug administration during session 2, occurs 7 ± 2 days after baseline visit
This 26-item VAS measures subjective and physiological effects of a medication using mood states as well as questions about the dose of medication. The measure consists of 7 questions about potential drug effects, and each response is rated on a scale of 0 to 100, with 0 reflecting not at all feeling the effect and 100 reflecting very much feeling the effect. The score is the sum of the 7 responses. The minimum value is 0 and the maximum value is 700.
30 minutes post-drug administration during session 2, occurs 7 ± 2 days after baseline visit

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.
University of Alabama at Birmingham

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: Karen L Cropsey, Psy.D., University of Alabama at Birmingham

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 (Actual)

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.
January 21, 2021

Primary Completion (Actual)

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.
June 15, 2024

Study Completion (Actual)

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.
June 15, 2024

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).
December 18, 2019

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.
January 29, 2020

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 5, 2020

Study Record Updates

Last Update Posted (Estimated)

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.
January 7, 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.
December 16, 2025

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.
October 1, 2025

More Information

Terms related to this study

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.
  • 300004505

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.

Yes

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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