Once-monthly treatment with extended-release injectable naltrexone helped patients who were dependent on opioids maintain an opioid-free state after detoxification, results from a placebo-controlled study demonstrated.
After 24 weeks of treatment, patients in the naltrexone treatment group had significant improvements compared with the placebo group in reduced opioid use, craving, and improved treatment retention.
Extended-release injectable naltrexone, marketed by Alkermes Inc. as Vivitrol, is an opioid antagonist administered once monthly by intramuscular injection and is approved in the United States for the treatment of alcohol dependence.
It is not currently approved by the Food and Drug Administration for the treatment of opioid dependence, but Alkermes has submitted a supplemental new drug application for that indication. The application has been designated as a priority review, “which means we're on an accelerated timetable and we're one step closer to making this treatment option available to patients with opioid dependence.” Dr. David R. Gastfriend, vice president for scientific communications at Alkermes, said at a press telebriefing held during the American Psychiatric Association's annual meeting in New Orleans.
He called opioid dependence a growing public health crisis in the United States. “The number of Americans addicted to prescription opioids or heroin has more than doubled since the year 2000,” he said. “There are now more than 1.3 million American adults who are opioid dependent.”
For the study, 250 patients who had completed an opioid detoxification within the previous week and were off all opioids for at least 7 days were randomized to 24 weeks of double-blind treatment with monthly injectable naltrexone 380 mg or to placebo.
The primary efficacy outcome was the response profile based on the rate of urine screening results negative for opioids during the last 20 weeks of the treatment period. Secondary outcomes included retention, physiologic evidence of opioid dependence per naloxone challenge, and a visual analog scale (VAS) of craving.
The mean age of study participants was 30 years and 88% were male. Dr. Gastfriend reported that a significantly higher proportion of patients in the injectable naltrexone group had opioid-negative urine screenings during the final 20 weeks of double-blind treatment compared with patients in the placebo group (90% vs. 35%, respectively). A higher proportion of them also tended to stay in treatment for the entire 24 weeks compared with those in the placebo group (53% vs. 38%).
Other differences that significantly favored the naltrexone group over the placebo group were the incidence of positive naloxone challenge and reductions in the VAS craving score. “Patients on placebo continued to crave opioids throughout the study at the same level that they started with at baseline,” Dr. Gastfriend noted.
“In contrast, the patients on extended-release naltrexone had a rapid decline in craving to half of their baseline level, and that was maintained throughout the study.”
No significant differences between the groups were observed in the incidence of clinical adverse events, and no severe adverse events or premature discontinuations attributable to adverse events occurred in the naltrexone group.
The most common adverse events experienced by patients in the naltrexone group were nasopharyngitis and insomnia.
“We believe these are compelling clinical data,” Dr. Gastfriend concluded. “Extended-release naltrexone may provide patients and physicians with a new treatment option: a non-addictive, once-monthly treatment for opioid dependence.”
The study, which was presented during a poster session at the meeting, was funded by Alkermes Inc. Dr. Gastfriend is a full-time employee of the company.
'Patients on extended-release naltrexone had a rapid decline in craving to half of their baseline level.'
Source DR. GASTFRIEND