Effect of Antivertigo Medications on Vestibular Function in Healthy Human Subjects

Chung, Jae Yong; Lee, Si Hyung; Hwang, Sang Ho

Abstract

BACKGROUND: Motion sickness is one of the major problems of aerospace medical concern. Vestibule plays an important role in giving rise to motion sickness. Drugs preventing motion sickness have a suppressive effect on the vestibular function through the antagonistic effect to some receptors in vesibular nuclei and vomiting center of central nervous system. We identified and quantified the effects of anti-motion sickness drugs on vestibule-ocular reflex in healthy human subjects.
METHODS
Fourty-five healthy male subjects were grouped to one of placebo, dimenhydrinate 50 mg, scopolamine (1 patch), or both scopolamine and dimenhydrinate group, and received rotation chair test before and after drug administration to obtain Vestibulo-ocular reflex (VOR) gain and phase in sinusoidal harmonic acceleration (SHA) with frequencies of 0.01, 0.02, 0.04 and 0.08 Hz. The delta gain and the delta phase by the drug administration were obtained and analyzed as pharmacodynamic effects.
RESULTS
Baseline gain and phase data were not different by the groups in all SHA frequencies. VOR gains were significantly decreased by 0.15~0.17 after dimenhydrinate administration. In the scopolamine group, there were significant decreases in 0.04 and 0.08 Hz by 0.14 and 0.15, respectively, but no difference in 0.01 and 0.02 Hz was observed. Increasing tendency in VOR phase lead was observed, especially in dimenhydrinate, but not significantly. There was no additive effect on the reduction of VOR gain when the two drugs were co-administered.
CONCLUSION
We quantitatively characterized how much the VOR parameters were changed by the drugs with different kinds of mechanism. Dimenhydrinate reduced the VOR gain by around 0.16. However, scopolamine probably has a minimal or no additive effect on VOR suppression.