Distribution of donepezil in postmortem casework

Donepezil is one of the primary treatments options for patients suffering from Alzheimer's Disease. In a review of more than 2200 postmortem donepezil positive blood specimens, 76% of concentrations were higher than the proposed therapeutic range. Means and medians were similar between central blood specimens and peripheral specimens, indicating minimal postmortem redistribution. Postmortem concentrations may not reflect those circulating antemortem. Mean and median postmortem blood concentrations were approximately 3-fold higher than those in antemortem blood specimens. Additionally, in cases where antemortem blood was available for testing, large increases in donepezil concentrations were reported between antemortem and postmortem specimens without documented administration by medical personnel. Elevated blood donepezil concentrations have been reported in multiple postmortem cases where cause of death was unrelated. The blood concentrations reported in cases where donepezil did not contribute to death overlapped with those in suspected drug overdose cases where other drugs may have been present. In 4 out of 5 suspected donepezil overdose cases, blood concentrations greater than 1000 ng/mL were reported, whereas less than 1% of all postmortem blood samples reviewed achieved these concentrations. Blood concentrations greater than 1000 ng/mL should be considered contributory when a drug overdose is suspected. Postmortem donepezil concentrations should be interpreted with caution in the context of a comprehensive case history.