Tissue distribution of mirtazapine (Remeron) in postmortem cases

Mirtazapine (Remeron) is a member of the relatively new class of tetracyclic antidepressants. There are published cases of mirtazapine's detection as an incidental finding in postmortem cases; however, case reports with associated tissue concentrations and interpretations are not available. This report documents the tissue distribution of mirtazapine in eight postmortem cases in which it was identified but did not contribute to the cause or manner of death. The following mean mirtazapine concentrations (milligrams per liter or milligrams per kilogram) were found: heart blood 0.12 (range, < 0.01-0.33, n = 7); peripheral blood 0.09 (< 0.01-0.14, n = 4); urine 0.61 (0.01-3.2, n = 7); liver 0.88 (0.04-3.6, n = 6), kidney 0.21 (0.02-0.48, n = 5); and bile 0.62 (0.11-1.6, n = 6). In each case, the mirtazapine concentration in heart blood was approximately equal to that of peripheral blood, indicating that postmortem redistribution was not a factor in evaluating postmortem blood concentrations in these cases. However, because the liver mirtazapine concentrations were 5-30 times the blood concentrations, the potential for postmortem redistribution cannot be excluded. Additionally, because urine concentrations of the parent compound were consistently greater than the blood concentrations, urine is an adequate screening specimen for mirtazapine.