Xylazine toxicity--literature review and report of two cases.

Xylazine is a veterinary sedative, analgesic or general anesthetic. Its pharmaceutical action results in sympathetic discharge via stimulation of alpha-2-adrenoceptors. In humans, toxicity consists of central nervous system depression, bradycardia and hypotension. The dosages known to produce toxicity in humans vary from 40 mg up to 2400 mg. Because of decomposition, xylazine blood concentrations in two homicide victims were unknown; however, the concentrations in the brain, liver, and kidneys were much higher in the 23-year-old female versus the 33-year-old male victim. A bottle of xylazine found on the crime scene had a concentration of 100 mg/mL. This 50 mL bottle had 32 mL remaining. Therefore at some point in time 18 mL had been utilized. The amount of available milligrams of xylazine (1800 mg) were enough to cause toxicity in both the woman and the man. Of interest was the fact that the partially skeletonized heads were found remote from the torsos, however, the concentration of xylazine in the body tissues provided a toxicological match of which head belonged to which body. Xylazine toxicity in humans and its relationship to these homicides will be the focus of this report.