Methadone Results in Longer Treatment Retention than Buprenorphine; Higher Doses are Associated with Longer Retention for both Medications

Previous studies have demonstrated similar effects of methadone and buprenorphine in reducing heroin use, but worse treatment retention among patients receiving buprenorphine. Many treatment providers cap buprenorphine doses at 16 mg because neuroimaging studies show high opioid receptor occupancy at that dose level, and some insurers discourage higher doses. Researchers conducted a 24-week multi-site open-label randomized controlled trial of buprenorphine versus methadone among 1267 subjects with opioid use disorder to measure retention in treatment. Medications were administered daily (except Sundays and holidays) by staff at opioid treatment programs.

• At 24 weeks, 74% of the patients receiving methadone remained in treatment (mean days = 141), versus 46% of those receiving buprenorphine (mean days = 104).
• Within the first 30 days, 25% of the patients receiving buprenorphine versus 8% of those receiving methadone dropped out of treatment.
• For both methadone and buprenorphine patients, higher dose was associated with more time in treatment.
• For methadone, doses of ≥60 mg resulted in retention rates of >80%, whereas rates for doses of ≤40 mg were <40%.
• For buprenorphine, doses of 30–32 mg resulted in retention rates close to 60%, whereas rates for doses of ≤10 mg were <20%.
• During the first 9 weeks of treatment, opioid positive urine results were lower in the buprenorphine versus methadone groups (odds ratio, 0.63), but were similar for weeks 10–24 at approximately 40% in both groups.

Comments:

This study demonstrated substantially better treatment retention for methadone compared with buprenorphine. Furthermore, retention was better at higher doses for both medications. Dose limits on buprenorphine at 16 mg should be reconsidered and warrant examination in controlled trials.

Alexander Y. Walley, MD, MSc

Reference:

Hser Y, Saxon AJ, Huang D et al. Treatment retention among patients randomized to buprenorphine/naloxone compared to methadone in a multi-site trial. Addiction.2014;109:79–87.