The Combination of Scopolamine and Psychostimulants for the Prevention of Severe Motion Sickness.

BACKGROUND AND AIMS: Severe motion sickness is a huge obstacle for people conducting precise aviation, marine or emergency service tasks. The combination of scopolamine and d-amphetamine is most effective in preventing severe motion sickness. However, this combination is not included in any present pharmacopoeia due to the abuse liability of d-amphetamine. We wanted to find a combination to replace it for the treatment of severe motion sickness.

METHODS AND RESULTS: We compared the efficacy of scopolamine, diphenhydramine, and granisetron (representing three classes of drugs) with different doses, and found that scopolamine was the most effective one. We also found scopolamine inhibited central nervous system at therapeutic doses and caused anxiety. Then, we combined it with different doses of psychostimulants (d-amphetamine, modafinil, caffeine) to find the best combination for motion sickness. The efficacy of scopolamine with modafinil (1 + 10 mg/kg) was equivalent to that of scopolamine with d-amphetamine (1 + 1 mg/kg); This combination also excited central nervous system and abolished the anxiety caused by scopolamine.

CONCLUSIONS: The optimal dose ratio of scopolamine and modafinil is 1:10. This combination is beneficial for motion sickness and can abolish the side effects of scopolamine. So, it might be a good replacement of scopolamine and d-amphetamine for severe motion sickness.