Benzodiazepine Use and Crash Risk in Older Patients

To the Editor.—Dr Ray's¹ Editorial that accompanies the article by Dr Hemmelgarn and colleagues²suggests that the common use of many of the short-elimination half-life benzodiazepines as hypnotics in the elderly may account for the lack of an association between these drugs and risk of injurious motor vehicle crashes. After bedtime administration, peak plasma-drug concentrations would occur at night. Thus, sleeping patients avoid the drug-associated cognitive and psychomotor impairments. Rapid drug elimination would result in minimal next-day effects. Ray¹cautioned that daytime use of these drugs as anxiolytics, as with longer half-life drugs, would result in peak pharmacological actions during the day and possible increased risk of injurious motor vehicle crashes. Hemmelgarn et al² did not indicate whether benzodiazepines with relatively short half-life were preferentially used as hypnotics rather than anxiolytics. Thus, lack of observed association between these drugs and driving-crash risk remains unexplained. Although next-day impairment associated with long half-life benzodiazepines such as diazepam is well established,³few studies have examined shorter half-life drugs.