Central nervous system effects of meclizine and dimenhydrinate: evidence of acute tolerance to antihistamines.

摘要: Relative daytime drowsiness and performance impairment produced by meclizine dimenhydrinate was assessed in 24 healthy male volunteers. Subjects received either dimenhydrinate, 100 mg, at 8:00 AM, 12:00 PM, 4:00 PM; meclizine, 50 with placebo PM or all three times this randomized, double-blind, three-way crossover study. Impairment of mental choice reaction time testing digit symbol substitution scores. Drowsiness self-assessed on the Stanford Sleepiness Scale a visual analog scale. Both antihistamines changes substitution, recognition time, subjective assessments sleepiness different from placebo. Expressed as change baseline, greatest reductions scores after occurred 3 hours first dose (6.6 +/- 7) were not measured (5.8 8), which 9 administered. Similar results obtained other psychometric test Self-rated 1 hour dose, significantly greater than largest degree 7 dose. The effects compared magnitude subsequent doses. effect data suggest possibility that acute tolerance to central nervous system develops multiple doses dimenhydrinate.