Role of the Endogenous Opioid System Underlying Modulation of Experimental Pain
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ClinicalTrials.gov Identifier: NCT01327326 |
Recruitment Status
:
Withdrawn
First Posted
: April 1, 2011
Last Update Posted
: July 13, 2012
|
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Condition or disease | Intervention/treatment | Phase |
---|---|---|
Temporomandibular Disorder Facial Pain | Drug: Naltrexone Drug: Placebo | Not Applicable |
Dysfunction in endogenous pain inhibitory systems has been proposed as a factor in the development and maintenance clinical pain disorders particularly in Temporomandibular Disorder (TMD). Dysfunction has been observed with a model known as diffuse noxious inhibitory controls (DNIC), but other models that engage inhibitory systems (offset analgesia) have not been fully evaluated in chronic pain patients.
DNIC evaluates an individual's capacity to engage endogenous pain inhibition. The paradigm is a spatial inhibition model based on the principle that "pain-inhibits-pain" in which pain in a local area is inhibited by a second pain that can be anywhere else in the body. DNIC is traditionally studied by observing a reduction of pain produced by a focal pain stimulus (contact heat) as a result of a second painful stimulus. Research from our lab and others suggests that pain inhibition is reduced in a number of chronic pain conditions. The investigators preliminary data suggests that pain inhibition during DNIC is modulated in part by endogenous opioids; however, results from other DNIC studies have been mixed. In addition, it is possible that reductions in the ability to engage endogenous inhibitory systems in chronic pain patients are due to a weakening of the endogenous opioid system. While pharmacological studies have been conducted with healthy cohorts, only one study has examined the opioid involvement in chronic pain patients.
Offset analgesia is thought to reflect a form of temporal pain inhibition which is usually defined by three stimulus temperature phases: a baseline phase followed by a manipulation phase in which the temperature is briefly increased and returns to the baseline temperature during an "offset" phase. A reduction in pain ratings is observed approximately 15s after the temperature drop (third phase), which is ~50% lower than ratings at the same time point for "constant" trials that continued 48°C for 40s. No studies have examined offset analgesia in a chronic pain cohort or its sensitivity of opioid blockade.
Study Type : | Interventional (Clinical Trial) |
Actual Enrollment : | 0 participants |
Allocation: | Randomized |
Intervention Model: | Crossover Assignment |
Masking: | Triple (Participant, Investigator, Outcomes Assessor) |
Primary Purpose: | Basic Science |
Official Title: | Opioid Modulation of Two Models of Pain Inhibition in Healthy Controls and Patients With Temporomandibular Disorder (TMD) |
Study Start Date : | December 2011 |
Actual Primary Completion Date : | July 2012 |
Actual Study Completion Date : | July 2012 |

Arm | Intervention/treatment |
---|---|
Active Comparator: TMD patients
Intervention:
|
Drug: Naltrexone
Oral, 50 mg, 1 Time Dose
Other Name: Revia
Drug: Placebo
Oral, 1 Time Dose
Other Name: Placebo/sugar pill
|
Active Comparator: Healthy controls
Intervention:
|
Drug: Naltrexone
Oral, 50 mg, 1 Time Dose
Other Name: Revia
Drug: Placebo
Oral, 1 Time Dose
Other Name: Placebo/sugar pill
|
- Post-drug efficacy of pain inhibition [ Time Frame: 1 hour after study medication (day 1) ]A change in the ability to reduce experimental pain sensitivity during two models of pain inhibition will be evaluated before and after medication.

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Ages Eligible for Study: | 18 Years to 50 Years (Adult) |
Sexes Eligible for Study: | All |
Accepts Healthy Volunteers: | Yes |
Inclusion Criteria:
- ages 18-50 years old
- Controls: pain-free based on Research Diagnostic Criteria (RDC) exam
- TMD: chronic musculoskeletal pain (face) based on Research Diagnostic Criteria (RDC) exam
Exclusion Criteria:
- Inability to adequately communicate and understand informed consent form;
- Inability to reliably rate pain intensity;
- Uncontrolled hypertension (or receiving treatment for hypertension with BP of greater than 140/95);
- Serious systemic (e.g. Diabetes, thyroid problems, etc.);
- Serious cardiovascular/pulmonary disease;
- Neurological problems with significant changes in somatosensory and pain perception at the intended stimulation sites (hand, foot);
- Serious psychiatric problems requiring treatment (schizophrenia, bipolar disorder);
- Other chronic pain conditions (e.g., low back pain, fibromyalgia);
- Any other ongoing acute pain problem (arthritis, injury-related pain); or,
- Irregular menstrual cycles (>40 days) or menstrual cycle disorders (e.g. PMS, dysmenorrhea).

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT01327326
Principal Investigator: | Christopher D King, PhD | University of Florida |
Responsible Party: | University of Florida |
ClinicalTrials.gov Identifier: | NCT01327326 History of Changes |
Other Study ID Numbers: |
APS2011 |
First Posted: | April 1, 2011 Key Record Dates |
Last Update Posted: | July 13, 2012 |
Last Verified: | July 2012 |
Keywords provided by University of Florida:
Pain modulation Experimental pain |
Additional relevant MeSH terms:
Temporomandibular Joint Disorders Temporomandibular Joint Dysfunction Syndrome Facial Pain Craniomandibular Disorders Mandibular Diseases Jaw Diseases Musculoskeletal Diseases Joint Diseases Muscular Diseases Stomatognathic Diseases |
Myofascial Pain Syndromes Pain Neurologic Manifestations Nervous System Diseases Signs and Symptoms Naltrexone Narcotic Antagonists Physiological Effects of Drugs Sensory System Agents Peripheral Nervous System Agents |