Concentrations of opiates and psychotropic agents in polydrug overdoses: a surprising correlation between morphine and antidepressants.

The relationship between postmortem concentrations of morphine and co-detected psychoactive drugs in fatal overdoses is examined. Morphine and other drugs were detected in 161 medicolegal autopsy cases. Subsets of these morphine-positive cases based on drug class were established, including opioids, antidepressants, ethanol, benzodiazepines, and "other." Each subset was split into high or low concentration groups based on median drug concentrations. Morphine concentrations of the [high] and [low] groups were compared, with no significant difference in morphine concentration identified in the opioid, ethanol, or benzodiazepine subsets. The "other" drug class was too heterogeneous for statistical assessment. Morphine concentrations did show a significant direct relationship (p = 0.01) with antidepressants, namely increased concentrations of antidepressant drugs are associated with an increased concentration of morphine. This trend probably remains even after excluding cocaine-positive cases. The unsuspected finding that postmortem concentrations of antidepressants positively correlate with morphine levels may be important in the treatment of depression in drug addicts.