Deaths of opiate/opioid misusers involving dihydrocodeine, UK, 1997-2007

What is already known about this subject: Dihydrocodeine (DHC) is an opioid analgesic sometimes prescribed as an alternative to other medications (e.g. methadone and buprenorphine) for opioid misuse. Its effectiveness is, however, still controversial. DHC prescription rates seem to be related to levels of DHC fatalities, possibly in relation to levels of disregard of the availability of supervised or interval dispensing of opioids, but no large-scale analysis of DHC fatalities has been carried out. We analysed here involvement of DHC in fatalities that occurred between 1997 and 2007 among individuals with a history of opiate/opioid misuse reported to the National Programme on Substance Abuse Deaths (np-SAD).

What this study adds: DHC, either alone or in combination, was identified in 584 fatalities. Typical cases identified were males in their early thirties. In accidental overdoses, DHC, which had been prescribed to 45% of the victims, was typically identified in combination with other drugs, such as heroin/morphine, methadone and hypnotics/sedatives. Both paracetamol and antidepressants were more typically identified in combination with DHC in suicides. Opiate/opioid misusers should be educated about risks associated with polydrug intake and prescribers should carefully consider a pharmacological intervention alternative to DHC (e.g. methadone, buprenorphine) when managing and treating opiate addiction.

Aims: Although its effectiveness is somewhat controversial, it appears that dihydrocodeine (DHC) is still prescribed in the UK as an alternative to both methadone and buprenorphine for the treatment of opiate addiction.

Methods: Data covering the period 1997-2007 voluntarily supplied by coroners were analysed. All cases pertaining to victims with a clear history of opiate/opioid misuse and in which DHC, either on its own or in combination, was identified at post-mortem toxicology and/or implicated in death, were extracted from the database.

Results: Dihydrocodeine, either alone or in combination, was identified in 584 fatalities meeting the selection criteria. In 44% of cases it was directly implicated in the cause of death. These cases represented about 6.8% of all opiate/opioid-related deaths during this period. Typical DHC cases identified were White males in their early thirties. Accidental deaths (96%) were likely to involve DHC in combination with other psychoactives, mainly heroin/morphine, hypnotics/sedatives and methadone. Both paracetamol and antidepressants were found in proportionately more suicide cases than in accidental overdoses. DHC had been prescribed to the decedent in at least 45% of cases.

Conclusions: Opiate/opioid misusers should be educated about risks associated with polydrug intake. More in particular, co-administration of DHC with heroin, methadone and benzodiazepines may increase the risk of accidental fatal overdose. Prescribers should carefully consider pharmacological intervention alternative to DHC (e.g. methadone, buprenorphine) when managing and treating opiate addiction. More resources are required to do prospective research in this area.