The effects of burial on drug detection in skeletal tissues

Skeletal tissues have recently been investigated for use in post-mortem toxicology. Variables affecting drug concentration in these tissues, however, are still poorly characterized. In this work, the relative effects of burial on the response of enzyme-linked immunosorbent assay (ELISA) and gas chromatography-mass spectrometry (GC-MS) assays were examined. Rats were acutely exposed to ketamine or diazepam, euthanized and buried outdoors. After one month, the remains were exhumed and skeletal tissue drug levels were compared those of non-buried rats. A climate-controlled burial was also undertaken using defleshed bones to approximate an extended decomposition. Long bones (femora, tibiae) were isolated and separated into tissue type (diaphyseal bone, epiphyseal bone, and marrow), and according to treatment (i.e. buried or non-buried). Following methanolic extraction (bone) or simple homogenization (marrow), samples were analyzed with ELISA. Samples were then pooled according to treatment, extracted by solid phase extraction (SPE) and confirmed with GC-MS. Under the conditions examined, the effects of burial appear to be drug and tissue dependent. Ketamine-exposed tissues demonstrated the greatest differences, especially in bone marrow. In diazepam-exposed tissues, burial did not seem to greatly affect drug response and some gave greater assay response compared to the non-buried set. Overall, the data suggest that fresh tissue samples may not be representative of decomposed samples in terms of skeletal tissue drug levels.