The comparative toxicology and major organ pathology of fatal methadone and heroin toxicity cases.

In order to determine the comparative toxicology and systemic disease of cases of death due to methadone and heroin toxicity, 1193 coronial cases of opioid overdose that occurred in New South Wales, Australia between 1 January 1998 and 31 December 2007 were inspected. These comprised 193 cases in which cause of death involved methadone toxicity (METH) and 1000 cases in which cause of death involved heroin toxicity in the absence of methadone (HER). METH cases were significantly more likely to have benzodiazepines (63.7% vs. 32.2%), and less likely to have alcohol (23.6% vs. 42.7%) detected. METH cases were significantly more likely to be diagnosed with pre-existing systemic pathology (94.3% vs. 79.9%), and multiple organ system pathology (68.8% vs. 41.4%). Specifically, METH cases were more likely to have cardiac (58.9% vs. 34.5%), pulmonary (53.6% vs. 30.9%), hepatic (80.7% vs. 62.8%) and renal (25.0% vs. 9.5%) disease. Given the notable differences in toxicology and disease patterns, great caution appears warranted in prescribing benzodiazepines to methadone users, and regular physical examinations of methadone treatment patients would appear clinically warranted.