Mechanisms underlying postmortem redistribution of drugs: a review.

Postmortem drug concentrations do not necessarily reflect concentrations at the time of death, as drug levels may vary according to the sampling site and the interval between death and specimen collection. These site- and time-dependent variations are called "postmortem redistribution" (PMR). The underlying mechanisms are complex and of different types. Passive drug release from drug reservoirs such as the gastrointestinal tract, liver, lungs, and myocardium may occur immediately after death and, later on, cell autolysis and the putrefactive process participate in redistribution. There is evidence that basic lipophilic drugs with a large distribution volume are particularly susceptible to PMR. Nevertheless, this cannot explain the actual PMR of some nonbasic, nonlipophilic drugs. In addition, the persistence of drug metabolism immediately after death must be considered. Consequently, it is of great importance to analyze specimens from different sampling sites in order to detect potential PMR and avoid misinterpretation of results.