Tanum 2017: the naltrexone shot vs daily buprenorphine-naloxone in Norway

What they tested

At 5 addiction clinics in Norway, 159 adults with opioid dependence who had recently been through detox were randomly assigned to extended-release naltrexone 380 mg, injected into a muscle every fourth week (80 people), or buprenorphine-naloxone taken daily at a flexible dose of 4 to 24 mg (79 people). Everyone knew which treatment they got (open-label).

It was a noninferiority trial, designed to test whether the shot was at least as good as buprenorphine-naloxone. Opioid medication treatment of this kind is the most commonly prescribed treatment for opioid dependence. The main measures were staying in the trial, opioid-free urine tests, and days of heroin and other illicit opioid use.

What they found

Of the 159 participants, 105 (66.0%) completed the trial. Time in treatment on the shot was noninferior to buprenorphine-naloxone, a mean of 69.3 vs 63.7 days, and the difference between them was not significant (P = .33).

The share of opioid-negative urine tests averaged 0.9 on the shot and 0.8 on buprenorphine-naloxone, which met the test for noninferiority.

When the researchers tested for superiority, people on the shot used significantly less heroin and other illicit opioids. There were no significant differences in the use of most other illicit drugs.

Limits

• It lasted only 12 weeks, so it says nothing about longer-term results.
• It was open-label: patients and staff knew who got which medicine.
• Everyone had already been detoxified before randomization, so the trial doesn't show how many people would drop out while trying to get off opioids before a first shot.
• Most participants were men; 44 (27.7%) were women.

What it means if you're considering naltrexone

For people with opioid use disorder who have already made it through detox, this trial suggests the monthly naltrexone shot works about as well as daily buprenorphine-naloxone over 12 weeks. The US X:BOT trial, which randomized people before detox, found the shot's main weakness is getting started, so the two trials together point to induction as the hard part.