Patterns of opiate use in a heroin maintenance programme

Rationale: Little is known about patterns of opiate use by heroin addicts. Objectives: To describe opiate use over time among heroin addicts who had access to legally prescribed intravenous heroin and oral opiates. Methods: Analysis of daily drug administration records of 37 patients enrolled in the Geneva heroin maintenance programme for 4-29 months (total 23 136 patient-days). Results: The average dose of intravenous heroin was 466 mg/day; the total opiate dose, after conversion of oral opiates to heroin-equivalents, was 543 mg/day. Patients received intravenous heroin only on 39% of days, oral opiates only on 7% of days, and mixed regimens on 49% of days; the remaining 4% of days were spent outside the programme, usually on oral opiates. The daily dose of heroin-equivalents increased during the first trimester in the programme, by 30 mg/day per month (95% confidence interval 12-46 mg/day per month), but decreased gradually thereafter, by 12 mg/day per month (95% confidence interval, 8-17 mg/day per month). In patients who alternated between heroin and methadone, 1 mg methadone typically replaced 4.1 mg heroin. During follow-up, five patients switched to methadone maintenance, five underwent detoxification, and three were discharged for noncompliance with regulations. Conclusions: Heroin users who have facilitated access to legally prescribed drugs consume about 0.5 g heroin per day. Consumption patterns vary, but the daily amount of opiates remains stable or decreases over time. A substantial minority of patients elect for alternative treatments after several months of heroin maintenance.