COMPARISON OF BUPRENORPHINE AND METHADONE-MAINTENANCE IN OPIATE ADDICTS

As a maintenance agent for opioid dependency, buprenorphine offers adv antages such as a lower level of dependence and minimal withdrawal sym ptoms, due to its partial agonist properties at the mu-opioid receptor . Previous studies have shown 8 mg sublingual buprenorphine to be equi valent to 60 mg oral methadone in terms of retention rate and opioid-n egative urine levels. In a 24-week, ongoing European study, 34 opioid- dependent subjects were assessed; 16 receiving buprenorphine and 18 me thadone. A free dosing schedule was used with no upper limit for metha done dosing but with a maximum buprenorphine dose of 8 mg. Screening p rior to the study excluded subjects with polysubstance dependence, som atic disease and/or HIV infection. Primary outcome measures were absti nence from other drugs, for which subjects provided weekly urine sampl es for analysis of opioids, cocaine and benzodiazepines, and retention in treatment. Patients in the buprenorphine group provided a greater proportion of negative urine samples, in particular cocaine-negative s amples, compared with the methadone group, although this was not stati stically significant. Retention in the buprenorphine group was signifi cantly lower than in the methadone group, suggesting that the 8 mg bup renorphine limit may have biased the results in favour of methadone, a nd that this dose may have been too low for those subjects with high l evels of dependence. However, buprenorphine is clearly effective in th e more motivated subjects and further investigation in this subgroup i s recommended.