Postmortem redistribution of morphine in rats

Area of Science:

• Forensic Toxicology
• Pharmacology
• Postmortem Medicine

Background:

• Morphine is frequently detected in postmortem blood samples.
• Determining if morphine levels indicate cause of death is crucial.
• Postmortem redistribution of morphine has not been previously investigated.

Purpose of the Study:

• To investigate the phenomenon of postmortem morphine redistribution.
• To determine if postmortem morphine concentrations differ from antemortem levels.
• To assess the impact of postmortem redistribution on interpreting morphine levels in forensic cases.

Main Methods:

• Adult Wistar rats were administered morphine (4 mg/kg, intramuscular).
• Cardiac blood samples were collected at the time of death (2 hours postdose).
• Morphine concentrations were measured at 24 and 96 hours postmortem.

Main Results:

• Morphine concentrations in cardiac blood significantly increased from 41.4 ng/ml at death to 111.9 ng/ml at 24 hours postmortem (p = 0.00036).
• No significant additional increase was observed at 96 hours postmortem (98.7 ng/ml).
• Endogenous substances cross-reacting with the morphine assay were found, contributing minimally (3%) to the total accumulation.

Conclusions:

• Substantial redistribution of morphine occurs after death.
• Elevated postmortem morphine levels do not necessarily represent antemortem concentrations.
• Interpretation of postmortem morphine findings requires consideration of redistribution effects.