A pilot study to determine the usefulness of the urinary excretion of methadone and its primary metabolite (EDDP) as potential markers of compliance in methadone detoxification programs.

Fourteen subjects (selected on the basis of compliance with the methadone-maintenance program prescribed by the consultant psychiatrist in charge of their treatment) undergoing opiate detoxification by methadone-replacement therapy were studied to determine if a relationship exists between the dose of methadone prescribed and the urinary excretion of methadone and/or its primary metabolite, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP). After the derivation of this relationship, it was hoped that the urinary concentrations of methadone and/or EDDP could be used as a noninvasive technique to monitor the methadone compliance of 56 drug abusers. Despite statistically significant correlations (p<0.001) between methadone dose and urine concentrations of methadone and EDDP, the large variation in concentrations measured in the urine of drug abusers negated the possibility of any clear-cut relationship being confirmed. However, it may be possible to use excretion data to monitor individual compliance but only through long-term monitoring of individual subjects to establish their own intraindividual variation in excretion patterns.