Pharmacokinetics and postmortem changes of cimetidine in body tissues

Cimetidine concentrations in body tissues were pharmacokinetically examined, together with their postmortem changes, to assess the toxicological effect of this drug from the aspect of forensic medicine. For the pharmacokinetic study, rats were pithed at 0.5, 1.0, 2.0, 4.0 or 8.0 hours after an intravenous injection of the drug (33.3 mg/kg), and their tissue samples were immediately collected to be analyzed by high-performance liquid chromatography (HPLC). The concentrations of cimetidine in the blood and muscle decreased below the lower detection limit at 8 hours after the injection, while the drug could still be detected in the brain, lung, liver, kidney, spleen and adipose tissue. The ratios of the cimetidine concentrations in the muscle, lung and spleen to that in the blood were nearly constant until 4 hours after the injection, while those in the liver, kidney and adipose tissue increased as time elapsed. Postmortem changes of cimetidine concentrations were examined using the tissue samples collected 0, 1 and 2 days after death. There was no statistical significance in the postmortem changes in cimetidine concentrations in the body tissues over the two-day period of examination. The experimental results indicated that the muscle, lung and spleen together can serve as samples for toxicological analysis to evaluate the effect of cimetidine, regardless of various postmortem factors, including the availability of blood.