Analysis of Acute Benzodiazepine Poisoning Cases in Critical Care Departments and Police Agencies in Japan during 1996.

Abstract

A retrospective survey of 669 cases of acute benzodiazepine poisoning admitted between January and December 1996 to 59 critical care departments was carried out. A review and retrospective analysis of the records of 95 deceased persons who had ingested benzodiazepines in 27 police prefectural jurisdictions in Japan during the same period, was performed to compare these cases and postmortem medicolegal cases of acute benzodiazepine poisoning. The majority of cases in both groups were deliberate self-poisoning (82.7% and 83.2%, respectively). Efforts to decrease morbidity and mortality from acute drug poisoning should target drugs taken frequently in serious and lethal overdoses. This study confirmed that flunitrazepam, triazolam, etizolam, and nitrazepam were the main agents ingested in cases of acute benzodiazepine poisoning in both the critical care and postmortem groups. More specifically flunitrazepam was the derivative most commonly used in the postmortem group. The statistically significant difference was thought to be attributable to the characteristics of the pharmacokinetic parameters of flunitrazepam, which has a short time to peak interval and a relatively long elimination half-life. In other words, rapid onset and prolonged coma contribute to successful suicide. The majority of patients in the critical care group (82.8%) and in the postmortem group (76.8%) had not undergone plasma or urinary drug screening tests. The lack of drug identification may result in serious diagnostic errors or wrong estimates of severity as well as interfere with scientific progress in the study of acute drug poisoning. Six deaths (0.9% of total) were recorded in the critical care departments as a result of poisoning following ingestion of benzodiazepines in combination with other drugs. Five of them were cases of cardiopulmonary arrest on arrival at the hospital. Therefore, most deaths related to benzodiazepines have occurred outside the hospital as a result of prolonged comatose periods in persons who were not discovered. The fact that acute benzodiazepine poisoning is a kind of the iatrogenic disease in Japan should be taken into consideration, since in most of the cases of poisoning the benzodiazepines were prescribed by a physician and given to the patient by a pharmacist. We regard careless prescriptions and routine dispensation of benzodiazepines as being among the reasons why the number of cases of acute poisoning fails to decrease. Accordingly, to prevent acute benzodiazepine poisoning, it is important to control the clinical use of benzodiazepines (especially flunitrazepam, triazolam, etizolam, nitrazepam) more appropriately by monitoring medication use and carefully counseling patients.