Benzodiazepine Overdose

Benzodiazepine overdose describes the ingestion of one of the drugs in the benzodiazepine class in quantities greater than are recommended or generally practiced. Death as a result of taking an excessive dose of benzodiazepines alone is uncommon (vs Combined drug intoxication) but does occasionally happen. Deaths after hospital admission are considered to be low. However, combinations of high doses of benzodiazepines with alcohol, barbiturates, opioids or tricyclic antidepressants are particularly dangerous, and may lead to severe complications such as coma or death. The most common symptoms of overdose include central nervous system (CNS) depression and intoxication with impaired balance, ataxia, and slurred speech. Severe symptoms include coma and respiratory depression. Supportive care is the mainstay of treatment of benzodiazepine overdose. There is an antidote, flumazenil, but its use is controversial.

As benzodiazepines are one of the most highly prescribed classes of drugs they are commonly used in self-poisoning by drug overdose. The various benzodiazepines differ in their toxicity since they produce varying levels of sedation in overdose. A 1993 British study of deaths during the 1980s found flurazepam and temazepam more frequently involved in drug-related deaths causing more deaths per million prescriptions than other benzodiazepines. Flurazepam, now rarely prescribed in the United Kingdom and Australia, had the highest fatal toxicity index of any benzodiazepine (15.0), followed by temazepam (11.9), vs. benzodiazepines overall (5.9), taken with or without alcohol. An Australian (1995) study found oxazepam being less toxic and less sedative and temazepam more toxic and more sedative than most benzodiazepines in overdose. An Australian study (2004) of overdose admissions between 1987 and 2002 found alprazolam, which happens to be the most prescribed benzodiazepine in the U.S. by a large margin, to be more toxic than diazepam and other benzodiazepines. They also cited a review of the Annual Reports of the American Association of Poison Control Centers National Data Collection System, which showed alprazolam was involved in 34 fatal deliberate self poisonings over 10 years 1992–2001, compared with 30 fatal deliberate self poisonings involving diazepam. In a New Zealand study (2003) of 200 deaths Zopiclone, a benzodiazepine receptor agonist had similar overdose potential as benzodiazepines.