Pupillometry and Pain Thresholds Patients Substituted by Methadone and Buprenorphine

Study Overview
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Brief Summary
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The purpose is to study the relation between pupillary diameter measured under scotopic conditions, and the pain thresholds measured at the time of peak and residual effect of methadone/buprenorphine in opiate-dependent patients following a substitution program.

Detailed Description
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Patients substituted since at least 3 months shall be included during a regular control visit. Each session shall consist in check for toxics in urine sample; measurement of pupil diameter; measurement of mechanical punctuate pain threshold; measurement of mechanical bone pain threshold. A first session shall be done at time of residual effect of the opiate. A second session shall be done at time of peak effect of the opiate.

Official Title
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Pupillometry and Pain Thresholds Patients Substituted by Methadone and Buprenorphine.

Conditions
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Opiate Dependent, Previous Illicit Drug Use

Intervention / Treatment
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* Drug: Buprenorphine and Methadone Hydrochloride


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: substitution treatment stable since at least 3 months capacity to understand the protocol likely to come to visits covered by French welfare Exclusion Criteria: chronic pain concomitant acute pain pregnancy or breast feeding relevant mental disease peripheral neuropathy diabetes regular intake of ketamine neuroleptic concomitant treatment

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| buprenorphine<br> | Drug: Buprenorphine and Methadone Hydrochloride<br>* To study the relation between pupillary diameter measured under scotopic conditions, and the pain thresholds measured at the time of peak and residual effect of methadone / buprenorphine in opiate-dependent patients following a substitution program.<br>|
| Methadone Hydrochloride<br> | Drug: Buprenorphine and Methadone Hydrochloride<br>* To study the relation between pupillary diameter measured under scotopic conditions, and the pain thresholds measured at the time of peak and residual effect of methadone / buprenorphine in opiate-dependent patients following a substitution program.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Measurement of the pupil diameter |  | 24 hours after the last dose of treatment | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| - The mechanical punctuate pain threshold as measured by Electronical Von Frey |  | 24 hours after the last dose of treatment, 3 hours after the last dose of methadone and 1 hour ½ after the last dose of buprenorphine | 
| - The mechanical pressure pain threshold measured by Algometer on the tibial bone |  | 24 hours after the last dose of treatment, 3 hours after the last dose of methadone and 1 hour ½ after the last dose of buprenorphine | 
| - The pupil diameter measured in scotopic .conditions (via infrared camera) at the hypothetical peak effect of either methadone or buprenorphine. |  | 24 hours after the last dose of treatment, 3 hours after the last dose of methadone and 1 hour ½ after the last dose of buprenorphine | 
| - The pupil diameter measured in photopic conditions (via infrared camera) at the hypothetical residual effect of either methadone or buprenorphine |  | 24 hours after the last dose of treatment, 3 hours after the last dose of methadone and 1 hour ½ after the last dose of buprenorphine | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Analgesics, opioids, Opiate substitution treatment, Methadone, Buprenorphine, Hyperalgesia, Pupil, Pain, Psychophysics, previous illicit drug intake, under a substitution program