Trial · NCT04251819

Buprenorphine Plus Baclofen to Increase Analgesia in Healthy Volunteers

NCT04251819, Phase 2, Phase 3, Terminated, University of Alabama at Birmingham; results first posted 2026-01-07

3 sourcestrials-2026-11-12-0.5.0

Cite this record

ConductScience Library. Buprenorphine Plus Baclofen to Increase Analgesia in Healthy Volunteers. Trials, record NCT04251819. Release trials-2026-11-12-0.5.0, 12 Nov 2026. https://conductscience.org/library/trials/NCT04251819

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Trial

As registered on ClinicalTrials.gov, in the graph's capture of the registry.

Title: Buprenorphine Plus Baclofen to Increase Analgesia in Healthy Volunteers
NCT number: NCT04251819
Status: Terminated
Phases: Phase 2, Phase 3
Enrollment: 19 participants, actual
Lead sponsor: University of Alabama at Birmingham
Conditions: Acute Pain, Analgesia
Interventions: Placebos, Baclofen 5 mg, Baclofen 10mg
First posted: 2020-02-05
Last updated: 2026-01-07
Results first posted: 2026-01-07

Source ClinicalTrials.gov

Registered outcomes14

Each outcome the trial registered, primary first, in ClinicalTrials.gov's words.

List	Outcome	Time frame	Description
Primary	Pain Threshold	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.
Primary	Pain Threshold	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.
Primary	Pain Tolerance	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.
Primary	Pain Tolerance	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.
Primary	Temporal Summation of Pain	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.
Primary	Temporal Summation of Pain	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.
Primary	Conditioned Pain Modulation	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.
Primary	Conditioned Pain Modulation	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.
Primary	Suprathreshold Pain Response	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
Primary	Suprathreshold Pain Response	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 to 10 of 14Source ClinicalTrials.gov

See all 14 registered outcomes

Outcomes14

Each outcome the trial posted results for, in ClinicalTrials.gov's words.

Type	Outcome	Time frame	Population	Units	Measured as
PRIMARY	Pain Threshold	Baseline		Degrees Celsius	MEAN
PRIMARY	Pain Threshold	1.5 hours post-drug administration during session 2, occurs 7 ± 2 days after baseline visit	Data were missing.	Degrees Celsius	MEAN
PRIMARY	Pain Tolerance	Baseline		Degrees Celsius	MEAN
PRIMARY	Pain Tolerance	1.5 hours post-drug administration during session 2, occurs 7 ± 2 days after baseline visit	Data were missing.	Degrees Celsius	MEAN
PRIMARY	Temporal Summation of Pain	Baseline	Data were missing.	units on a scale	MEAN
PRIMARY	Temporal Summation of Pain	1.5 hours post-drug administration during session 2, occurs 7 ± 2 days after baseline visit	Data were missing.	units on a scale	MEAN
PRIMARY	Conditioned Pain Modulation	Baseline	Data were missing.	units on a scale	MEAN
PRIMARY	Conditioned Pain Modulation	1.5 hours post-drug administration during session 2, occurs 7 ± 2 days after baseline visit	Data were missing.	units on a scale	MEAN
PRIMARY	Suprathreshold Pain Response	Baseline	Data were missing.	units on a scale	MEAN
PRIMARY	Suprathreshold Pain Response	1.5 hours post-drug administration during session 2, occurs 7 ± 2 days after baseline visit	Data were missing.	units on a scale	MEAN

1 to 10 of 14Source ClinicalTrials.gov

See all 14 outcomes

Results by group42

Each measurement the trial posted, group by group, in the words and numbers it posted.

Outcome	Group	Value	Spread	Units
Pain Threshold	Placebo	44.62	Standard Deviation 2.13	Degrees Celsius
Pain Threshold	Baclofen 5mg	45.11	Standard Deviation 3.04	Degrees Celsius
Pain Threshold	Baclofen 10mg	43.56	Standard Deviation 3.77	Degrees Celsius
Pain Threshold	Placebo	43.82	Standard Deviation 2.46	Degrees Celsius
Pain Threshold	Baclofen 5mg	43.95	Standard Deviation 2.70	Degrees Celsius
Pain Threshold	Baclofen 10mg	42.06	Standard Deviation 3.14	Degrees Celsius
Pain Tolerance	Placebo	48.17	Standard Deviation 1.52	Degrees Celsius
Pain Tolerance	Baclofen 5mg	46.84	Standard Deviation 2.00	Degrees Celsius
Pain Tolerance	Baclofen 10mg	47.34	Standard Deviation 2.11	Degrees Celsius
Pain Tolerance	Placebo	47.84	Standard Deviation 1.86	Degrees Celsius

1 to 10 of 42Source ClinicalTrials.gov

See all 42 results by group

Participant flow9

How many started, completed or left each group, period by period.

Period	Milestone	Group	Participants
Overall Study	STARTED	Placebo	6
Overall Study	STARTED	Baclofen 5mg	8
Overall Study	STARTED	Baclofen 10mg	5
Overall Study	COMPLETED	Placebo	6
Overall Study	COMPLETED	Baclofen 5mg	8
Overall Study	COMPLETED	Baclofen 10mg	5
Overall Study	NOT COMPLETED	Placebo	0
Overall Study	NOT COMPLETED	Baclofen 5mg	0
Overall Study	NOT COMPLETED	Baclofen 10mg	0

Source ClinicalTrials.gov

Adverse events6

Each adverse event the trial posted, group by group: the participants affected out of those at risk.

Type	Event	Organ system	Group	Affected	At risk	Events
other	Buprenorphine Poisoning	Injury, poisoning and procedural complications	Placebo	1	6	1
other	Buprenorphine Poisoning	Injury, poisoning and procedural complications	Baclofen 5mg	0	8	0
other	Buprenorphine Poisoning	Injury, poisoning and procedural complications	Baclofen 10mg	0	5	0
serious	Emergency Department Visit	Injury, poisoning and procedural complications	Placebo	1	6	1
serious	Emergency Department Visit	Injury, poisoning and procedural complications	Baclofen 5mg	0	8	0
serious	Emergency Department Visit	Injury, poisoning and procedural complications	Baclofen 10mg	0	5	0

Source ClinicalTrials.gov

Adverse event totals9

The totals the trial posted for each group.

Total	Group	Affected	At risk
Total, all-cause mortality	Placebo	0	6
Total, all-cause mortality	Baclofen 5mg	0	8
Total, all-cause mortality	Baclofen 10mg	0	5
Total, other adverse events	Placebo	1	6
Total, other adverse events	Baclofen 5mg	0	8
Total, other adverse events	Baclofen 10mg	0	5
Total, serious adverse events	Placebo	1	6
Total, serious adverse events	Baclofen 5mg	0	8
Total, serious adverse events	Baclofen 10mg	0	5

Source ClinicalTrials.gov

Papers0

The papers the trial lists on ClinicalTrials.gov.

None in this release.

Grants0

The grants NIH RePORTER links to the trial, newest funded first: NIH's, and some of AHRQ's, CDC's, FDA's and VA's. Each shows its title, principal investigators, organization and funder in its newest year.

None in this release.

Trial comparisons0

Comparisons of the trial's two groups, calculated by ConductScience from the counts it posted.

None in this release.

Tests0

The ConductCognition tests this trial's registered outcomes name, as ScienceGraph matched them in trial-tests-2026-11-12-0.2.1.

None in this release.

Data dates

The day each source was copied for this release.

ClinicalTrials.gov: 2026-11-12; ClinicalTrials.gov
Results, from AACT: 2026-03-23; AACT
NIH grant links: 2026-11-13; NIH RePORTER

Sources 3

ClinicalTrials.gov's posted results, through CTTI's AACTFreely available. Acknowledgement requested
ClinicalTrials.govNo license stated
NIH RePORTER's clinical studies and project filesPublic domain

Each source's terms

ClinicalTrials.gov's posted results, through CTTI's AACTClinicalTrials.gov data via Aggregate Analysis of ClinicalTrials.gov (AACT), CTTI. CTTI makes its materials freely available and requests acknowledgement. https://aact.ctti-clinicaltrials.org/documentation/299
ClinicalTrials.govnone stated
NIH RePORTER's clinical studies and project filesPublic domain (NIH RePORTER)

ClinicalTrials.gov's data carry an international copyright outside the United States: https://clinicaltrials.gov/about-site/terms-conditions.

For software

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