Opioid addiction patients given extended-release naltrexone had about twice the rate of treatment retention at 6 months as those given oral naltrexone, a study of 60 adults shows.
“These study findings have immediate clinical relevance for treatment of opioid use disorder, at a time when an opioid epidemic continues unabated in the United States,” wrote Maria A. Sullivan, MD, PhD, of Columbia University, New York, and her colleagues.
Naltrexone remains an alternative to agonist treatment for opioid use disorder, but adherence to a daily pill regimen is often poor. “Extended-release (XR) parenteral formulations of naltrexone, as monthly injection or implants, circumvent the daily pill requirement and have shown promising effectiveness,” the researchers said.
In a study published in the American Journal of Psychiatry, 60 opioid-dependent adults who had completed an inpatient detoxification program were randomized to 50 mg/day of oral naltrexone (or 100 mg on Mondays and Wednesdays and 150 mg on Fridays for those living alone) plus behavior therapy or a 380-mg intramuscular injection of XR-naltrexone monthly plus behavior therapy.
After 6 months, 57% of patients in the XR-naltrexone group were retained in treatment, compared with 28% of the oral group (hazard ratio, 2.18), reported Dr. Sullivan and her colleagues.
A total of 40 adverse events were reported. Insomnia was the most common and occurred in 52% of the patients; it was more common in the oral group, compared with the extended-release group (70% vs. 35%, respectively). A total of nine serious adverse events were reported, and five participants discontinued the study as a result. However, only one event, a case of hives determined to be an allergic reaction, was attributed to the study drug.
The findings were limited by several factors, including the small size, open-label design, and lack of urine data for patients after they discontinued the study, the researchers noted. However, the results “support the use of XR-naltrexone combined with behavioral therapy as an effective treatment for patients seeking opioid withdrawal and nonagonist treatment for preventing relapse to opioid use disorder,” they said. In addition, given the difference in effectiveness and the high risk of a failed treatment with oral naltrexone,” they said.
The study was supported in part by grants from the National Institute on Drug Abuse. Dr. Sullivan had no financial conflicts to disclose.
SOURCE: Sullivan MA et al. Am J Psychiatry. 2018. doi: 10.1176/appi.ajp.2018.17070732.