Analysis of drugs and poisons

By Fumio Moriya Introduction

Blood and urine are the common specimens for drug analysis in both antemortem and postmortem cases. Usually, urine is used for drug screening using immunoassays at the first step; secondly, the drug detected is chromatographically quantitated with blood. The data obtained are carefully assessed with taking the values reported in references into consideration together with clinical and postmortem findings; the judgement of poisoning and its degree is made comprehensively.

The periods between samplings and analysis and the storage conditions of samples are very important for assessment of analytical results for human specimens, especially for postmortem specimens; the postmortem intervals and the degree of putrefaction should be always taken into consideration. Even in a vial (in vitro) after sampling and also inside the whole body postmortem, drugs may be metabolized by coexisting enzymes [1, 2]; postmortem production [3, 4] and decomposition [5] can take place by the action of bacterial growth. In the autopsy cases, the source of blood sampled should be recorded exactly; the high concentrations of drugs present in the lung, heart and liver can diffuse into the surrounding tissues, resulting in higher drug concentrations in blood there [6]. When a large amount of a drug is present in the stomach, it diffuses into the surrounding tissues and blood postmortem [7, 8]. The urinary bladder sometimes contains a large amount of urine with a high drug concentration; in such a case, diffusion of a drug from the bladder into blood of the femoral vein can take place postmortem [9]. When vomitus containing a high concentration of a drug is aspirated into the trachea or bronchus, or local anaesthetic jelly is applied to the trachea upon intubation, the concentration of the drug in heart blood may be enhanced postmortem [10, 11]. Even if analytical instruments are excellent, correct diagnosis of poisoning is impossible without considering the above phenomena. In analysis of drugs and poisons, there are many subtle points to be considered; in this chapter, pitfalls and cautions are presented for correct analysis in poisoning.

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