Two cases of fatal zopiclone overdose

Two cases of death due to the ingestion of zopiclone are presented. Quantitative determinations of zopiclone yielded 1.4-3.9 mg/L in the blood, 0.81 and 8.7 mg/kg in the liver, and 13.5 and 133 mg in the stomach contents. Drug concentrations were interpreted relative to the case findings, published data, and a limited evaluation of therapeutic concentrations found in two cases of therapeutic zopiclone use. Zopiclone was extracted from buffered blood or digested liver or both with n-butyl chloride and analyzed by high-performance liquid chromatography with ultraviolet detection. Liver samples were digested at pH 7 to avoid zopiclone decomposition.