Criteria for judging whether postmortem blood drug concentrations can be used for toxicologic evaluation

Postmortem blood drug concentrations tend to be regional-dependent. The aim of this study was to establish preliminary criteria, based on analytical findings of drugs in body fluids, for objectively judging whether drug concentrations determined in postmortem blood are usable for toxicologic evaluation. The study involved 11 autopsy cases in which no obvious putrefaction was observed. Twelve drugs were assayed; the cumulative frequency of detection was 16. The drug concentrations in cerebrospinal fluid and pericardial fluid were averaged, and the ratio between this average concentration and the concentration in femoral venous blood was determined. The mean ratio was close to 1, with a small standard deviation (0.94 +/- 0.20). From these results, the following criteria were drawn: 1) when the ratio of average cerebrospinal fluid/pericardial fluid drug concentration to blood drug concentration is within a range of 0.6-1.4, the postmortem blood drug concentration is usable for toxicologic evaluation; and 2) when the ratio is outside this range, the average cerebrospinal fluid/pericardial fluid concentration should be used as an alternative to drug concentration is postmortem blood.