Human xylazine overdose: a comparative review with clonidine, phenothiazines, and tricyclic antidepressants.

We report a case of horse tranquilizer (xylazine) overdose from oral ingestion in man, detail a gas-liquid chromatography/mass spectrometer method for xylazine assay in the blood and urine, and suggest the management of acute poisoning. We present a comparative review of some toxicological properties that xylazine shares with the pharmacologically related clonidine and with the structurally related phenothiazines and the tricyclic antidepressants.