Effects of antihistamines,chlormezanone and alcohol on psychomotor skills related to driving

Summary The effects of diphenhydramine, meclastine, and chlormezanone, alone or in combination with alcohol, on psychomotor skills related to driving have been investigated in 300 healthy volunteers. A choice reaction test and two coordination tests were employed. — Diphenhydramine caused sedation, partly independent of the dose, and slightly impaired psychomotor performance. Some subjects were exceptionally sensitive to diphenhydramine induced impairment of skills. It enhanced the effects of alcohol. — Meclastine did not impair psychomotor performance. A 1.5 mg dose did not enhance the effects of alcohol, but 3 mg did, although it was less potent than 50 mg of diphenhydramine. — Chlormezanone 200 mg had a relaxing effect which became apparent as a shortened reaction time at 30 min. Chlormezanone 400 mg did not affect psychomotor performance, nor did it enhance the effects of alcohol on psychomotor skills.