Kunøe 2009: a 6-month naltrexone implant after in-patient treatment

What they tested

Patients who had finished in-patient treatment for opioid dependence and wanted to stay off drugs were randomly assigned to a 6-month naltrexone implant or their usual aftercare. Assignment was open, meaning patients and staff knew who had the implant.

Drug use and other outcomes were checked at a 6-month follow-up, and blood tests tracked naltrexone levels.

What they found

Over the 180 days, the implant group had on average 45 fewer days of heroin use and 60 fewer days of any opioid use than the usual-aftercare group (both P<0.05).

Blood tests showed naltrexone levels stayed above 1 ng/ml for the full 6 months.

Two patients died during the study. Neither had received an implant.

Limits

• It was small, with 56 patients.
• It was open-label and compared the implant with usual care rather than a placebo implant, so knowing their treatment may have affected how people behaved or reported.
• Patients were motivated and had just completed in-patient treatment, so results may not apply to people still using.

What it means if you're considering naltrexone

For people coming out of rehab for opioid use, this Norwegian trial suggests a long-acting implant can cut opioid use in the months that follow. The authors described the population as motivated, which matters when applying the result to others.

No naltrexone implant is FDA-approved. The long-acting form approved in the US is Vivitrol, a monthly shot.