Aims: To assess peripheral anti-H1 and central nervous system (CNS) activity of single increasing doses of rupatidine fumarate (RU), a new antihistamine/platelet-activating factor antagonist compound, in comparison with hydroxyzine and placebo.
Methods: Eighteen healthy young subjects of both sexes took part in a crossover, randomised, double-blind, placebo-controlled study. Treatments tested were: RU 10, 20, 40 and 80 mg and hydroxyzine 25 mg, as a positive standard. Before and several times after drug intake, peripheral anti-H1 activity was appraised by the skin reactivity to intradermal injection of histamine. CNS effects were also obtained by objective tests of psychomotor performance and subjective mood scales.
Results: All active treatments showed a significant reduction of the wheal and flare reaction in relation to placebo, RU displaying a potent dose-dependent inhibition pattern. The global nonparametric Friedman test to changes from placebo in 15 objective variables from psychomotor performance showed a significant impairment of similar magnitude after hydroxyzine 25 mg (p = 0.01) and RU 80 mg (p = 0.02), but this was slower in development and recovery after the latter. After RU 40 mg, a smaller impairment was also obtained (p = 0.04). Activity (p = 0.01) and drowsiness (p = 0.02) scales showed significant changes, the subjects feeling less active and more drowsy after all active treatments.
Conclusion: RU presents a potent dose-dependent peripheral anti-H1 activity, displaying psychomotor impairment activity only at the highest dose (80 mg), while therapeutically relevant lower doses (10 and 20 mg) were similar to placebo.