Computerized task battery assessment of cognitive and performance effects of acute phenytoin motion sickness therapy.

Phenytoin was previously evaluated as an efficacious anti-motion sickness therapy in more than 24 individuals. To be effective, this short-term, novel therapy requires serum levels in the anticonvulsant range; therefore, it became imperative that the effects of phenytoin upon cognition and performance be quantified. Each subject was tested on a performance battery (Criterion Task Set) on two occasions while on either phenytoin treatment or placebo for subsequent statistical comparison. We evaluated 23 subjects with phenytoin serum levels ranging from 8.9 to 23.9 micrograms/L. While subjects with the higher serum levels consistently reported subjective side effects, there was no statistically significant degradation of sensory, cognitive, or performance capabilities compared to placebo.