Pupillometry and Pain Thresholds Patients Substituted by Methadone and Buprenorphine

Pupillometry and Pain Thresholds Patients Substituted by Methadone and Buprenorphine.

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.

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.

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