Consumption of buprenorphine and other drugs among heroin addicts under ambulatory treatment: results from cross-sectional studies in 1988 and 1990.

We assessed the prevalence of consumption of buprenorphine and other drugs among heroin addicts under ambulatory treatment in two cross-sectional studies conducted in 1988 (188 subjects) and in 1990 (197 subjects). Patients were enrolled in one of three different programmes: methadone maintenance programme (MMP), antagonist maintenance programme (AMP) and drug-free programme (DFP). Information given by participants was compared with results of urine screening for drugs. Urine samples were tested using enzyme immunoassay for the detection of heroin, cocaine, dextropropoxyphene, cannabis and benzodiazepines, and radioimmunoassay for buprenorphine. Sixty-six percent of patients in 1988 and 71% of patients in 1990 reported having consumed buprenorphine at some time during their history of drug dependence (period prevalence) and 5.9% and 6.1%, respectively, tested positive to the drug (point prevalence). In over 70% of these patients consumption was by the intravenous route. Consumption of cannabis, cocaine and benzodiazepines was also very high in the study population. Overall, patients in the DFP group consumed the largest number of the drugs tested, while those in the AMP group consumed the smallest number. Abuse of buprenorphine could be more widespread than previously reported.