Equilibrium and Vestibular Safety of Modafinil in Healthy Volunteers.

Modafinil, as a wake-promoting agent, is commonly used to relieve fatigue during military operations. However, there is a lack of clarity regarding the effects of modafinil on the equilibrium and vestibular organs, especially when prescribing this drug to flight crewmembers. The objective of this study was to evaluate the equilibrium- and vestibular-related safety effects of modafinil. In a randomized, double-blind, placebo-controlled, crossover study, 10 healthy male volunteers received a single 200-mg oral dose of modafinil or placebo. Equilibrium and vestibular functions were assessed 2 h after oral administration by the sensory organization test (SOT), adaptation test (ADT), and video head impulse test (v-HIT). There was no change in the equilibrium scores of the six SOT conditions or the composite scores between the modafinil and placebo groups. Statistically significant differences were not observed for the sway energy score (SES) in the toe-down test. In the toe-up test, the SES decreased by 16.7% in the modafinil group relative to the placebo group in trial 2, while the differences in other trials were not statistically significant. In the v-HIT, there was no significant difference in the gain of each semicircular canal between the two groups. A single 200-mg dose of modafinil did not cause any impairment to vestibular function, equilibrium ability, or adaptive balance response; in fact, modafinil might have a positive effect on adaptation function in healthy volunteers. These findings preliminarily suggest that there is no hidden risk of vestibular dysfunction among aviation employees using modafinil.