The efficacy of low-dose intranasal scopolamine for motion sickness

Scopolamine is an effective motion sickness prophylactic, but oral and transdermal formulations are slowly absorbed. To enhance absorption and potentially efficacy, an intranasal formulation of scopolamine (INSCOP) was tested.

There were 16 motion sickness susceptible subjects with an average age of 23.5 +/- 3.0 yr and an average score of 11.3 +/- 4.7 on the Modified Motion Sickness Susceptibility Questionnaire-Short Form who volunteered to participate in the study. Each subject was given 0.4 mg of INSCOP and a placebo in a randomized, double-blind crossover design and, at 40 min post-dose, experienced Coriolis cross-coupling in a staircase progression until moderate nausea. Efficacy data and cognitive, physiological, and alertness assessments were collected during baseline control and throughout experimental testing.

Intranasal scopolamine significantly increased the mean number of head movements tolerated [INSCOP 275.9 +/- 120.5, Placebo 230.7 +/- 76.4; t (15) = 2.21]. Estimation of medication absorption via plasma concentration indicated the drug was absorbed relatively rapidly to measurable levels by 15 min post-administration. Diastolic blood pressures and heart rate were significantly lower after administration of INSCOP compared to placebo. No significant cognitive or medication side effects were reported. Subjects reported no significant decrease in alertness as indicated by the Karolinska Sleepiness Scale.

Results of the current study strongly suggest that intranasal scopolamine is efficacious for the treatment of motion sickness in susceptible individuals with no significant cognitive or sedative effects. Intranasal delivery offers a promising alternative for use in dynamic operational environments without cognitive detriment or increased side effects.