Buprenorphine/naloxone versus methadone in opioid dependence: a longitudinal survey

Buprenorphine and methadone are widely used for the treatment of opioid dependence, but their diversion and/or misuse are frequent. In principle, buprenorphine/naloxone combination therapy should be associated with a lower frequency of drug abuse/misuse than methadone. This study assessed the efficacy of the substitution of buprenorphine treatment with the buprenorphine/naloxone combination in opioid-dependent patients.

3812 drug-addicted outpatients selected from 10 Italian Public Services for Addiction (Ser.T.) centres in Naples (Italy) were enrolled: 3105 (81.5%) were treated with methadone and 707 (18.5%) with buprenorphine. The buprenorphine treatment was switched to buprenorphine/naloxone (4:1), and the patients were followed for about 1 year. The number of subjects still on treatment after 1 year, their status according to social, educational and toxicologic (assessed by a urine toxicology test) parameters were assessed.

1 year after the therapy switch, the number of patients still on treatment was similarly reduced with methadone (2883; -7.5%) and buprenorphine/naloxone (632; -10.6%; p=0.369). However, in patients treated with buprenorphine/naloxone, a significant improvement was reported in social life status (63% versus 39% of the buprenorphine/naloxone and methadone treated subjects, respectively, were married/cohabiting p<0.001), in the educational level (43% of buprenorphine/naloxone treated versus 32% of the methadone treated subjects obtained at least a high school certificate, p<0.001) and in the toxicological conditions (53% of buprenorphine/naloxone treated subject versus 30% of methadone treated individuals had opioid- and cocaine- negative urine tests, p<0.001).

These preliminary data suggest that buprenorphine/naloxone treatment of opioid dependence reduces the percentage of treated subjects similarly to methadone, and is associated with an improvement in social life, educational and toxicological conditions, compared with methadone treatment. However, we cannot exclude a selection bias, i.e. patients who were more likely to stabilize their opiate dependence switched to buprenorphine/naloxone.