SITE-TO-SITE VARIABILITY OF DRUG CONCENTRATIONS IN SKELETAL-MUSCLE

The homogeneity of drug concentrations in skeletal muscle was assessed in eight fatal overdoses. Ten to 30 random samples were taken from le g muscle weighing 1,650 to 7,985 g. For cafes involving paracetamol th e mean muscle-to-blood ratio ranged from 0.1 to 1.1 (n = 4) for amitri ptyline 1.1 to 3.6 (n = 3), and for dothiepin 0.8 to 2.1 (n = 2), The coefficient of variance was large for all drugs, ranging from 10.5 (ca rbamazepine) to 50 (thioridazine), Skeletal muscle is not homogeneous with respect to drug concentrations in fatal overdose cases. Of 16 ins tances of drug detection in blood 2 (nortriptyline and promethazine) w ere not detected in muscle. Muscle-to-blood drug ratios varied signifi cantly among cases, possibly influenced by survival time after drug in gestion. Quantitative interpretations of muscle drug levels present si gnificant difficulties. However, skeletal muscle can be used for quali tative corroboration of blood analyses and is a suitable specimen for drug detection where none other is available.