High dose ondansetron for reducing motion sickness in highly susceptible subjects.

BACKGROUND: Ondansetron is currently being explored as a treatment for motion sickness due to its proven prophylactic effect on post-operative nausea, the nausea and vomiting associated with chemotherapy, and its lack of side effects. This study sought to compare the effectiveness of placebo, dimenhydrinate, and ondansetron for preventing motion sickness in highly susceptible subjects. METHODS: A total of 63 subjects with a history of frequent motion sickness and positive report of self-treatment of motion sickness with over-the-counter medications were divided into 3 groups of 20 (3 were disqualified). Depending on their group assignment, subjects were given placebo, dimenhydrinate, or ondansetron 1 h before being rotated at 20 rpm while making head movements. Symptoms of motion sickness and electrogastrogram (EGG) data were collected prior to and during rotation. RESULTS: There were no differences between the groups in number of head movements tolerated, time rotating, or symptom questionnaire scores. All groups showed a marginally significant decrease in normal 3 cycle per minute activity [F (1.45) = 3.04, p = 0.088] and a significant increase in gastric tachyarrhythmia [F (1,45) = 9.71, p = 0.003], a pattern typically associated with motion sickness development. CONCLUSION: Neither ondansetron or dimenhydrinate prevented motion sickness in groups of highly susceptible people. Continued development of new treatments is necessary.