Australasian Science: Australia's authority on science since 1938

Post Mortem: What Happens to Drugs after Death?


Many factors result in drug concentrations rising, falling or even disappearing after death.

By Michael Kennedy

Drug levels can rise, fall or even disappear entirely after death, potentially leading to incorrect conclusions about murder, suicide and drug overdoses.

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In 1865 the bodies of Mary Pritchard and her mother were exhumed and found positive for antimony. Up to that point in time, poisonings were detected not by laboratory testing for drugs but entirely by symptoms exhibited before death and examination of organs at autopsy. Pritchard’s husband, Dr Edward William Pritchard, was presumably unaware of these new laboratory techniques. He was charged with murder and later became the last person to undergo public execution in Scotland.

Post mortem detection of drugs has moved on since Pritchard’s day. Laboratories now routinely measure nanogram quantities of drugs from samples of blood, urine, vitreous humour in the eye, bile, gastric contents and often liver. They can also undertake analysis of hair, bone, brain and other body parts.

Prior to death, the concentration of a drug in any part of the body will be a function of drug absorption, its distribution throughout the body, metabolism and elimination. The big question for each death is what to make of the various drug concentrations found.