Fatal diphenidol poisoning: a case report and a retrospective study of 16 cases

Diphenidol hydrochloride (DPN), a nonphenothiazinic antiemetic agent used primarily in patients with Meniere disease and labyrinthopathies to treat vomiting and vertigo, is considered to be a relatively safe drug. Since it was first approved in the United States in 1967, this drug has been widely used in Latin America and Asia and has contributed to sporadic suicidal and accidental poisonings in mainland China and Taiwan. However, its toxic or lethal concentration ranges have not yet been determined. We report a case of a 23-year-old female who suffered from DPN poisoning that resulted in death. At autopsy, there were no typical pathological findings, except for cerebral edema with high acetylcholinesterase expression. Postmortem analysis of DPN revealed 45 µg/ml in heart blood, 39 µg/ml in femoral vein blood, 141 µg/g in the liver, and 53 mg in the gastric contents. These concentrations indicated that the cause of death was DPN poisoning. The circumstances indicated that the manner of death was suicide. We also present a retrospective study, in which we review and summarize the literature from 1998 to 2014 and describe 16 cases of poisoning, including information from autopsy reports and postmortem drug concentrations. In forensic practice, drug residues at the scene, patients with convulsions and disturbance of consciousness, and rapidly occurring deaths, should draw attention to the possibility of this drug. Toxicological analysis and the exclusion of other diseases may ultimately be used to confirm DPN poisoning.