Benzodiazepines and alcohol are associated with cases of fatal buprenorphine poisoning

Background Although buprenorphine therapy has proved to be successful in opioid maintenance treatments, the drug is also widely abused in many countries by intravenous injection or sniffing (snorting). In Finland, buprenorphine is the most important abused opioid causing fatal poisonings. Purpose To evaluate the drug and alcohol findings as well as the cause and manner of death in all buprenorphine-related post-mortem cases for the age group 14-44 years in Finland from 2000 to 2008. Method This was a retrospective analysis of data on opioid-associated deaths in the Finnish comprehensive postmortem toxicology database based on medico-legal autopsies, case background information and laboratory analyses. Results Buprenorphine was found in 29% of all 1,363 opioid-positive cases, and buprenorphine poisoning was the cause of death in 182 cases out of 391 buprenorphine-positive cases (47%). In these fatal poisonings, the blood buprenorphine/norbuprenorphine concentration ratio was significantly higher than in cases with other causes of death. The manner of death in buprenorphine poisonings that were almost exclusively accidental differed significantly from other buprenorphine-related cases, which also involved diseases and suicides. Death was immediate in 10% of fatal buprenorphine poisonings, was delayed, during sleep, in 52%, and followed an unknown course of events in 38%. In immediate poisonings, the median blood buprenorphine concentration (3.0 mu g/l) was significantly higher than that in delayed poisonings (1.2 mu g/l). In most buprenorphine poisonings (92%), no opioids other than buprenorphine were involved, but benzodiazepines and alcohol were found in 82 and 58% of cases, respectively. The median concentrations of opioids and benzodiazepines in buprenorphine poisonings were in the therapeutic range. Only one fatal poisoning was found in which neither alcohol nor drugs other than buprenorphine were found. Conclusion A fatal buprenorphine poisoning is typically accidental, and the average victim is a 27-year-old male addict. Circumstantial and environmental factors seem to be crucial in determining the outcome of the poisoning.