Retention in Naltrexone Implant Treatment: Promising, but Not Conclusive

By increasing adherence, sustained-release formulations of naltrexone are hypothesized to be more effective than oral formulations, which by-and-large have shown little advantage over placebo among opioid-dependent patients. In this observational study from Norway, 61 patients recruited at discharge from medication-free residential drug treatment or prison received sustained-release naltrexone implants lasting 5–6 months. The main outcome measure was retention in treatment, defined as receiving a second implant 4–6 months after the first. Multivariable analyses of pretreatment participant factors associated with retention were also conducted.

• Thirty-one participants (51%) received a second implant. An additional 6 (10%) initiated opioid maintenance (3 patients) or long-term residential treatment (3 patients).

• Factors associated with retention included less injection drug use in the 30 days prior to study entry (OR 0.9, p=0.007), duration of longest employment (OR 1.4, p=0.017), and fewer days of worry about family problems (OR 1.7, p=0.034).

Comments:

Adding to promising evidence from 2 previous trials, this observational noncontrolled study suggests that sustained-release naltrexone may retain patients in treatment at rates approaching those observed in opioid-agonist treatment programs. However, comparative effectiveness trials, with opioid-agonist therapy as the comparison arm, are still needed before widespread use of sustained-release naltrexone can be recommended.

Hillary Kunins, MD, MPH, MS

Reference:

Kunøe N, Lobmaier P, Vederhus JK, et al. Retention in naltrexone implant treatment for opioid dependence. Drug Alcohol Depend. May 28, 2010 [E-pub ahead of print].