A fatality due to injection of tiletamine and zolazepam

A 22-year-old male with more than 28 needle marks on his right arm was found dead. First, he was suspected as a drug abuser. Blood, urine, spleen, and injection-site tissue was collected during autopsy. The blood and urine specimens were screened for drugs. Immunoassay studies did not show any illegal drugs. However, two unidentified peaks were isolated in both of these biological fluids by routine gas chromatography-flame-ionization detection (GC-FID) and thermionic specific detection. Additional gas chromatography-mass spectrometry analysis determined these two peaks to be tiletamine and zolazepam. These two agents are used in combination as veterinary anesthesia. The concentrations of these drugs in blood were quantitated by GC-FID and found to be 0.85 mg/L of tiletamine and 3.3 mg/L of zolazepam. In urine, tiletamine and its metabolite, 2-(ethylamino)-2-(2-thionyl) cyclohexanol, were identified to be present along with zolazepam. The concentrations of tiletamine and zolazepam in spleen were revealed to be 0.92 and 3.5 mg/kg, respectively. Injection-site tissue concentrations were determined to be 25.1 mg/kg tiletamine and 23.3 mg/kg for zolazepam. The cause of death in this case was determined to be due to the multiple drug intoxication of tiletamine and zolazepam.