Early-phase postmortem redistribution of the enantiomers of citalopram and its demethylated metabolites in rats.
The aim of this study was to investigate the early-phase postmortem redistribution of the enantiomers of citalopram (CIT) and its metabolites demethylcitalopram (DCIT) and didemethylcitalopram (DDCIT) in a rat model. Furthermore, we wanted to examine the role of the lungs as a reservoir of postmortem drug release and to investigate the influence of storage temperature (21 degrees C vs. 4 degrees C) on postmortem changes. Rats were administered a single CIT dose of 100 mg/kg (s.c.), and heart blood and lung samples were collected antemortem and 15 min postmortem for enantioselective high-performance liquid chromatographic analysis. About three times higher blood drug and metabolite levels were observed in the postmortem rats than in the antemortem rats (p < 0.0001). Refrigeration at 4 degrees C did not prevent, but significantly reduced, the postmortem increase in heart blood CIT levels as compared to the concentrations in the rats stored at 21 degrees C (p < 0.05). The lung drug concentrations were lower postmortem than antemortem (p < 0.05). The enantiomeric (S/R) concentration ratios of CIT and metabolites in blood and lungs were of similar magnitude before and after death. The parent-drug-to-metabolite ratios for CIT/DCIT were unchanged after death. In conclusion, this study shows that heart blood CIT and metabolite levels increase rapidly after death. Further, a fall in postmortem CIT concentrations in the lungs was observed, indicating that the lungs seemed to represent one major source of drug release during early-phase postmortem redistribution.
Kugelberg
Fredrik C
FC
Department of Clinical Pharmacology, Faculty of Health Sciences, Linköping University, SE-581 85 Linksping, Sweden. fredrik.kugelberg@imv.liu.se
Kingbäck
Maria
M
Carlsson
Björn
B
Druid
Henrik
H
D000818:Animals; D015283:Citalopram / Q000032:analysis* / Q000737:chemistry / Q000493:pharmacokinetics; D008297:Male; D008745:Methylation; D011180:Postmortem Changes; D051381:Rats; D017207:Rats, Sprague-Dawley; D017367:Selective Serotonin Reuptake Inhibitors / Q000008:administration & dosage / Q000032:analysis* / Q000737:chemistry / Q000493:pharmacokinetics; D013237:Stereoisomerism; D013997:Time Factors; D014018:Tissue Distribution
D015283:Citalopram; D017367:Selective Serotonin Reuptake Inhibitors