SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists

PH
DISTRIBUTION OF QUETIAPINE IN NINE POSTMORTEM CASES
Tara J. Valouch, B.S.'", Dwight Flammia, Ph.D., James K. Kuhlman, Ph.D., Virginia Division of Forensic
Science
Quetiapine (Seroquel ®) is an antipsychotic drug approved by US FDA in September 1997 for the
treatment of schizophrenia. It is classified as a dibenzothiazepine and structurally related to clozapine. The
molecular formula is C21H2sN30zS with a molecular weight of 383.6. It is believed to exert its
pharmacological effect through antagonism of sertonergic (5HT2) and dopaminergic (D2) receptors in the
brain. Quetiapine is extensively metabolized, but the pharmacological effect is primarily attributed to
parent drug. It is rapidly absorbed after oral administration, reaching peak plasma concentrations in 1.5 h.
The elimination half life is 6 h. Peak serum quetiapine concentrations range from 0.17 - 0.37 mgIL
following a single oral 75 mg dose to 0.19 0.63 mg/L following a 450 mg dose.
Nine postmortem quetiapine cases identified by the Virginia Division of Forensic Science toxicology
laboratories during 2003 are presented. Quetiapine was identified by full scan electron impact gas
chromatography-mass spectrometry (GCMS) following a basic drug extraction from blood. Quantitation
was performed using a basic solid-phase extraction followed by the addition of BSTF A and selected ion
monitoring GCMS. The following mean tissue concentrations and ranges were determined: heart blood
18.9 mgIL (0.53 - 76 mgIL, n = 4), peripheral blood 11.5 mg/L (0.46 - 37 mg/L, n = 6), urine 16.4 mg/L
(1.9 - 37 mg/L, n 6), liver 123 mg/Kg (7.2 510 mg/Kg, n = 9), and gastric 48.2 gIL (15-130 gIL, n = 4).
Medical examiners certified the cause of death in eight of the nine cases as combined drug toxicity. In one
case the cause of death was quetiapine toxicity and the manner of death was suicide. The quetiapine
concentrations in this case were 15 mglL in antemortem blood, 18 mgIL in peripheral postmortem blood,
and 89 mglKg in liver. Only one case contained both heart and peripheral blood (7.0mgIL and 3.4 mg/L
respectively). The heart/peripheral blood ratio was 2.0 suggesting postmortem redistribution.
Keywords: quetiapine, postmortem, distribution
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