Darke 2019: how people died while on naltrexone for opioid dependence

What they tested

Researchers searched Australia's National Coronial Information System for every death from 2000 to 2017 among people being treated with naltrexone for opioid dependence. They collected details on who died, how they died, their naltrexone treatment history, toxicology and organ findings.

They also measured naltrexone levels and compared morphine levels in people with and without naltrexone present.

What they found

The 74 people had a mean age of 32.5 years, and 81.1% were male. Opioid toxicity caused 86.5% of the deaths: 79.7% accidental and 6.8% deliberate.

55.4% were on oral naltrexone and 32.4% had a recent naltrexone implant. In five cases the person was going through opioid detox.

Among those screened, naltrexone was found in the blood or urine of 52.5%: 15.8% of people on oral naltrexone and 85.7% of people with an implant. The authors read the cases without naltrexone as a sign of how much taking the medicine as prescribed matters.

Fourteen people died of opioid toxicity with naltrexone present, and median blood naltrexone levels were within the reported therapeutic range. The authors say this shows overdose is possible while naltrexone treatment continues.

Limits

• It looked only at people who died, so it can't say how common death is on naltrexone or compare it with other treatments.
• It is observational, so it can't show whether naltrexone raised or lowered anyone's risk of death.

What it means if you're considering naltrexone

For people on naltrexone for opioid dependence, the main danger in these records was still opioid overdose. Often naltrexone was no longer detectable, which fits people having stopped their tablets, but some people overdosed with naltrexone still present. Being on naltrexone doesn't make an opioid overdose impossible.