Sullivan 2019: the naltrexone shot vs naltrexone pills for opioid use disorder

What they tested

Sixty adults with opioid dependence finished inpatient opioid withdrawal and were moved onto oral naltrexone. They were then randomly assigned to keep taking 50 mg pills daily (32 people) or switch to XR-naltrexone 380 mg, a monthly injection (28 people), for 24 weeks. The first shot was given before they left hospital.

Everyone got weekly behavioral therapy to support treatment and taking the medicine. People knew which form they were on (open-label).

What they found

16 of 28 people (57.1%) on the shot stayed in treatment for 6 months, compared with nine of 32 (28.1%) on pills (hazard ratio=2.18, 95% CI=1.07, 4.43).

The analysis adjusted for race, gender, route of opioid use and how much heroin people used at the start. Even on the shot, many people left treatment before 6 months.

Limits

• It was small, with 60 people.
• It was open-label, and everyone had already finished inpatient withdrawal, so it doesn't show how many people would manage to start the shot from outpatient care.
• The abstract reports staying in treatment, not relapse or drug use.

What it means if you're considering naltrexone

For people with opioid use disorder who choose naltrexone, this trial supports the monthly shot over daily pills, because taking a pill every day was the weak point. It is one small trial, and it measured staying in treatment, which isn't the same as staying off opioids.