Highway driving in elderly the morning after bedtime use of hypnotics: a comparison between temazepam 20 mg, zopiclone 7.5 mg and placebo

A major problem related to hypnotic drug use is residual sedation the morning after bedtime administration. This constitutes a particular safety hazard for patients who have to drive a car the next morning. Information on the severity of residual effects is mainly derived from studies conducted with young healthy volunteers. However, most users of hypnotics are older people who may be more sensitive to drug effects. The aim of this study was to evaluate the residual effects the morning after evening doses of temazepam 20 mg and zopiclone 7.5 mg on driving performance in healthy elderly drivers. Eighteen healthy elderly drivers (10 females and 8 males; mean age, 64.3 years) participated in a double-blind, 3-way crossover study. Treatments were single oral doses of temazepam 20 mg, zopiclone 7.5 mg, and placebo administered at bedtime. Subjects performed a standardized highway driving test between 10 and 11 hours after hypnotic intake. Before and after the driving test, cognitive performance was assessed. Driving performance did not differ between temazepam and placebo but was significantly impaired after zopiclone 7.5 mg (P <0.002). The results of the laboratory tests were in line with the effects on driving of both hypnotics. Temazepam 20 mg is unlikely to impair driving 10 hours or more after bedtime administration in healthy elderly aged 75 years or younger. Zopiclone 7.5 mg moderately impairs driving in the elderly at least until 11 hours after administration. The magnitude of impairing effects in the elderly was comparable with those found previously in younger volunteers.