Objective: To determine the effectiveness of 2 second-generation antihistamines in modulating motion sickness induced by Coriolis vestibular cross-coupling stimulation. Methods: This prospective, randomized, double-blind, crossover, placebo-controlled study was conducted in 18 healthy adults. Subjects were exposed to Coriolis vestibular cross-coupling in the laboratory using the Staircase Profile Test for baseline susceptibility and when under the influence of cetizirine, fexofenadine, and placebo. Subjective evaluation of sickness symptoms was based on the Graybiel diagnostic criteria of acute motion sickness, Golding's scale, and the Coriolis Sickness Susceptibility Index. Results: Repeated measures ANOVA and Friedman nonparametric ANOVA of rank tests revealed that there were significant differences in symptom assessments based on Graybiel's diagnostic criteria (pless than or equal to0.001), subjective symptoms of motion sickness (p less than or equal to 0.001), and state-anxiety (pless than or equal to0.001) before and after motion exposure. However, there are no significant differences between the baseline susceptibility to motion sickness and treatment with placebo, cetirizine, or fexofenadine. Conclusions: The failure of the second-generation antihistamines cetirizine and fexofenadine to prevent motion sickness suggests that the therapeutic actions of this class of antihistamines against motion sickness may be mediated through central versus peripheral receptors. The sedative effect of other antihistamines, such as hydroxyzine, may play a more significant role in alleviating motion sickness than previously thought.
