Hair Testing to Assess Consumption of Illicit Psychotropic Agents and Alcohol by Patients Treated With High-dose Buprenorphine and Methadone. Search for a Pharmacogenetic Contribution to Low Efficacy of Substitution Medications

Overview

Justification and aims of the study: The principal aim of use of opiate substitutes such as methadone or high-dose buprenorphine (HDB) is to reduce the need or the desire to consume the opiate to which the patient is addicted. Adjustment of the initial dose and regular re-evaluation of the efficacy of treatment are key elements in the success of such management. While too high a dose can be responsible for side effects leading to abandonment of treatment, too low a dose can induce the reappearance or even the reinforcing of parallel consumption of other psychoactive substances, in particular cocaine, alcohol and cannabis. The principal aim of this project is to determine the course of parallel consumption in patients who have been receiving a maintenance dose of methadone or HDB for at least two months, by analysis of a sample of hair, a biological matrix which is innovative for this type of study. Hair testing establishes a retrospective profile of consumption. The secondary aims of this project are (i) to validate the French versions of Handelsman's subjective and objective opiate withdrawal scales and to seek a possible correlation between high scores on these scales and the presence of parallel consumption, and (ii) to seek an association between polyconsumption and common functional polymorphisms of metabolic enzymes of methadone and HDB. Expected results: Hair testing, which has the particular advantage of a long detection window so that samples need only be taken at intervals, could improve the biological monitoring of patients on substitutive treatment. Validation of the French version of Handelsman's scales of objective and subjective signs of opiate withdrawal and search for any correlation with parallel consumption will enable these scales to be used in daily practice for clinical surveillance of patients on substitutive treatment. If a polymorphism of a metabolic enzyme of one or other of these molecules is detected, rapid genotyping of a simple saliva sample will be valuable in guiding the choice of medication when deciding on a treatment strategy

Methodology: The two populations of patients, one treated with methadone, the other with HDB, will be recruited in accordance with the ethical principles of the declaration of Helsinki, during consultations at a center for addiction treatment. One hundred and ten patients will be included in each of the two populations. Written informed consent will be obtained from each patient. Anonymity will be respected at inclusion and throughout. Using a sample of hair, testing for and measurement of the principal drugs (opiates, cannabis, cocaine, amphetamines) and the specific marker of ethanol consumption, ethyl glucuronide, will be performed by chromatographic techniques (high-performance liquid chromatography and gas phase chromatography) together with detection by mass or tandem mass spectrometry. This non-invasive sampling is more informative than blood tests, as it gives a retrospective profile of an individual's consumption over several months. Treatment efficacy will also be assessed using Handelsman's subjective and objective opiate withdrawal scales. Lastly, polymorphisms of the metabolic enzymes of methadone and HDB will be sought by real-time PCR in a saliva sample, a method which gives similar results without the need for venous blood sampling.