Monthly naltrexone shots (Vivitrol) worked as well as daily buprenorphine/naloxone (Suboxone) for treating opioid use disorder, according to the first head-to-head trial between the two.
In an open-label randomized controlled trial, retention in the extended-release naltrexone group was non-inferior to buprenorphine/naloxone at 12 weeks (mean time 69.3 and 63.7 days, respectively), according to Lars Tanum, MD, PhD, of the University of Oslo in Norway, and colleagues.
Naltrexone was also non-inferior for other primary outcomes including the number of opioid-negative urine drug tests, use of heroin, and use of other illicit opioids, the team reported online in JAMA Psychiatry.
"The main clinical implication of these findings is that extended-release naltrexone seems to be as safe and effective as buprenorphine/naloxone treatment for maintaining short-term abstinence from heroin, opioids, and other illicit substances in opioid-dependent individuals newly detoxified and/or discharged from inpatient treatment or prison."
The study wasn't funded outright by Alkermes, the maker of Vivitrol, but the company was "allowed to comment on the manuscript before submission for publication," according to the study's disclosure section.
Earlier this year, investigative reports found that Alkermes was using lobbyists to get Vivitrol written into state laws about opioid abuse treatment, and has persuaded drug courts to mandate Vivitrol over other drugs.
For the study, the researchers enrolled 159 patients with opioid dependence (mean age 36; 28% were women) who went through detoxification and were then randomized to buprenorphine/naloxone 4 to 24 mg/day (with a target dose of 16 mg/day) or to monthly naltrexone injections (380 mg).
After 12 weeks, 105 (66%) participants had attended all scheduled follow-up appointments and had taken their medication as prescribed. A total of 53 participants dropped out: 24 in the naltrexone group and 29 in the buprenorphine/naloxone group.
In addition to non-inferiority for retention, naltrexone was also non-inferior for:
- Number of opioid-negative urine drug tests (mean 0.9 and 0.8, respectively; P<0.001)
- Use of heroin (mean difference −3.2, P<0.001)
- Use of other illicit opioids (mean difference −2.7, P<0.001)
Extended-release naltrexone was superior for lower use of heroin and other illicit opioids, but not superior for the proportion of negative urine drug tests.
In terms of secondary outcomes, there were no significant differences between groups for the use of amphetamines, cocaine, alcohol, cannabis, or injecting drugs, but those on naltrexone had a significant reduction in benzodiazepine use, while the buprenorphine/naloxone group remained stable.
There were more adverse events among those on naltrexone (69% versus 34.7%, P<0.001), but only 10 participants discontinued treatment owing to adverse events: four in the naltrexone group and six in the buprenorphine/naloxone group. A number of events were related to withdrawal symptoms and were more frequent among the naltrexone group (28 patients, 39.4%, versus 10 patients, 13.9%).
There were no deaths, but more naltrexone patients reported having serious adverse events including pneumonia and withdrawal (8.5% versus 4.2%).
Tanum and colleagues noted that naltrexone induction required full detoxification to a greater extent than buprenorphine/naloxone treatment. In fact, the detoxification protocol was changed a year into the trial, which reduced the number of new adverse events related to naltrexone induction.
The researchers noted that the study was limited by a lack of blinding, as the use of placebo among newly detoxified opioid users was considered unethical. Also, participants likely recognized their treatment easily, given their long experience with opioid use.
Still, the researchers concluded that extended-release naltrexone was as effective and safe as buprenorphine/naloxone and should be considered a treatment for opioid-dependent patients.
Drugmaker Alkermes was allowed to comment on the manuscript before submission for publication.
The authors disclosed no financial relationships with industry.
- Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner
LAST UPDATED 10.20.2017