Postmortem toxico-kinetics of co-proxamol

Postmortem drug redistribution in suicidal poisonings by co-proxamol (dextropropoxyphene and paracetamol) has been studied. Analytical data for 8 tissue samples, including muscle and fat, up to 8 blood samples, and gastric and small bowel contents were obtained in 4 cases. Blood samples were taken from multiple sites at the start of autopsy and after 24 or 48 h. Concentrations of both drugs were site dependent with the lowest concentrations in peripheral blood. Paracetamol concentrations varied two to threefold and propoxyphene concentrations varied seven to tenfold. Pulmonary artery concentrations of paracetamol did not change significantly with time; propoxyphene concentrations typically increased twofold over 24 h and threefold over 48 h. Propoxyphene concentrations in the inferior vena cava increased unpredictably but occasionally significantly (up to sevenfold). For both drugs the most dramatic elevations of blood concentrations were seen in the aorta; in one case paracetamol rose to 1.9 g/l, 8 times the peripheral blood concentration and 4 times the liver level (454 mg/kg); propoxyphene rose to 191.5 mg/l, 55 times the peripheral blood concentration. This appears to reflect postmortem diffusion of unabsorbed drug from the gastric lumen. It is likely that markedly higher concentrations in the putrefactive fluid from the left pleural cavity as compared with the right also reflect diffusion from the stomach.