ABSTRACT
It is well recognized that postmortem [PM] drug levels in blood may be unstable as a consequence of redistribution artifact. Whereby drugs diffuse from their binding sites of high concentration in tissues and major organs, such as liver and lung, into blood. Also drugs can be expected to diffuse from gastric contents into blood. When measuring drug concentrations after death, it is important to consider the phenomenon of PM drug redistribution. PM drug concentrations may not be a true reflection of the antemortem one and as a result, wrong conclusions could be made about the cause of death. There is few published evidence for most drugs and poisons to show the important differences in their PM concentrations in blood and tissues according to choice of sampling site, sampling time, handling of samples including containers, preservation and documentation and type of laboratory investigation carried out on PM samples. The present work was carried out to evaluate experimentally in rabbits PM behavior of ethyl and methyl alcohol in relation to their concentration in different blood sampling sites at different time intervals. Furthermore to assess the effect of site of PM blood sampling on the level of ethyl alcohol and methyl alcohol at time of autopsy in human cadavers and compare it with the results from rabbit experiments. The study was conducted on ninety male rabbits as experimental animals, and the human cadavers that were positive on screening to ethanol [n = 4] and methanol [n = 3] during the period of the study. Rabbits were divided into three groups [30 rabbits each], two groups for each drug, which were given the LD50 of the drug. Blood samples [2ml] were drawn from right and left sides of the heart and femoral vein from each group of rabbits, immediately, twelve hours and twenty-four hours after death. As regards human cadavers, blood samples [5m1] were drawn from right and left sides of the beau and femoral vein at time of autopsy. Experimental and human blood sample extracts were analyzed by gas chromatography. The study showed that ethanol was detected in the control group after 12h PM. The highest mean value recorded was 681 g/ml in 24h PM Rt. cardiac. No significant changes could be detected in immediate PM blood concentration for ethanol and methanol from different sampling sites. The study also revealed that PM blood concentration for ethanol and methanol increased over time for different sampling sites. Where up to 24h PM femoral [peripheral] blood drug concentrations were the closest to the immediate PM values, followed by Rt. cardiac then Lt. cardiac blood. It was noticed also that up to 12h PM femoral [peripheral] blood methanol concentration could be used as a reliable indicator for the immediate PM values. Experimental animal studies, when interpreted carefully, are indicative of the PM drug changes observed in human, denoting that femoral [peripheral] blood is the best site for drug sampling