Delayed elimination in humans after ingestion of colchicine: Two fatal cases of colchicine poisoning.

Colchicine has been widely used in the treatment of acute gout over the years, but it has a narrow therapeutic index, and overdose can be life threatening. A method using ultra-high-performance liquid chromatography-tandem mass spectrometry system was applied in two fatal cases of colchicine poisoning in this study to the determination of colchicine in blood. In case 1, a 19-year-old man suffered from depression and ingested 160 colchicine tablets (each 0.5 mg). The concentration of colchicine in his blood samples showed a fluctuating trend and kept above the therapeutic steady-state concentration for 5 days. In case 2, a 70-year-old female patient with a history of gout and chronic colchicine intake ingested five times the usual dose of colchicine (5 mg) and died after 12 days of medical care, with 5 ng/mL of colchicine in her blood sample. Our findings suggest that the delayed elimination and accumulation in humans after colchicine overdose could keep the concentration of colchicine maintaining above the therapeutic steady-state concentration for many days before dying, probably along with a fluctuating trend.