[Prevalence of buprenorphine use by heroin addicts undergoing treatment]

After buprenorphine was introduced as an analgesic, several clinical observations have stimulated the investigation of its potential abuse by heroin addicts. To evaluate the prevalence of buprenorphine use by a group of heroin abusers being treated on an outpatient basis, a cross-sectional study was carried out where the information given by the 188 subjects was verified by urine drug analyses. The patients had three different therapeutic modalities: methadone maintenance program (MMP), antagonist maintenance program (AMP), and drug-free program (DFP). The urine samples were analyzed with an enzyme immunoassay technique for the detection of heroin, methadone, dextropropoxyphene, cannabis and benzodiazepines. Buprenorphine was investigated with a radioimmunoassay technique. Overall 66% of the patients admitted having used buprenorphine throughout their toxicologic history (period prevalence) and 6.7% had positive urine controls for this drug (5% in the MMP group, 0% in the AMP group and 12% in the DFP group) (point prevalence). In 72% of the cases the drug was administered intravenously. In addition, a clinically statistically significant association was found between positivity for heroin and buprenorphine. The possible tolerance to the latter is suggested by the fact that the mean current dose was higher than the mean initial dose. In the study population, the use of cannabis and benzodiazepines was also very high. The results suggest that most patients had a previous history of buprenorphine use. This drug could have a higher potential for abuse than that found in previous experimental studies.