Redistribution of basic drugs into cardiac blood from surrounding tissues during early-stages postmortem

The objective of this study was to elucidate the mechanism(s) responsible f or increases in the concentrations of basic drugs in cardiac blood of bodie s in a supine position during early-stages postmortem. The concentrations o f basic drugs in car dine blood and other fluids and tissues of three indiv iduals who had used one or more basic drugs were examined. The results were compared with those obtained in experiments using rabbits. In the first ca se, autopsy of whom was performed approximately 12 h after death, methamphe tamine was detected and its concentrations were in the order: lung much gre ater than pulmonary venous blood > blood in the left cardiac chambers (left cardiac blood) much greater than pulmonary arterial blood > blood in the r ight cardiac chambers (right cardiac blood). In the second case, autopsy of whom was performed approximately 9 h after death, methamphetamine and morp hine were detected and their concentrations in the left cardiac blood were roughly twice those in the right cardiac blood. The methamphetamine and mor phine concentrations in the lung were 2 to 4 times higher than those in car diac blood samples. In the third case. autopsy of whom was performed approx imately 2.5 days after death, the pulmonary veins and arteries were filled with chicken fat clots. Toxicological examination revealed the presence of four basic drugs: methamphetamine, amitriptyline, nortriptyline and prometh azine. Their concentrations in the lung were 5 to 300 times higher than tho se in cardiac blood, but postmortem increases in the concentrations of thes e drugs in the cardiac blood were not observed. In the animal experiments, rabbits were given 5 mg/kg methamphetamine intravenously or 20 mg/kg amitri ptyline subcutaneously and sacrificed 20 min or 1 h tilter, respectively. T he carcasses were left in a supine position at the ambient temperature for 6 h after or without ligation of the large vessels around the heart. Por th e groups with ligated vessels, the mean ratios of the drug concentrations i n both left and right cardiac blood samples 6 to 0 h postmortem were about 1, whereas in those without ligated vessels, these ratios were about 2 and 1, respectively. The order of the methamphetamine and amitriptyline concent rations in blood and tissue samples were roughly: lungs > myocardium and pu lmonary venous blood > cardiac blood, inferior vena caval blood and liver. Our results demonstrate that when bodies are in a supine position, (1) basi c drugs in the lungs diffuse rapidly postmortem into the left cardiac chamb ers via the pulmonary venous blood rather than simply diffusing across conc entration gradients, and (2) basic drugs in the myocardium contribute littl e to the increases in their concentrations in cardiac blood during the earl y postmortem period.