Topical application of betahistine improves eustachian tube function in an animal model.

Betahistine dihydrochloride, a drug used widely in the systemic treatment of balance disorders such as Ménière's disease, was found to improve eustachian tube function when applied topically in the nasopharynx of rats. The study tested the effect of betahistine, a histamine receptor agonist, on eustachian tube function and tested the involvement of H1 and H3 histamine receptors. Eustachian tube function was measured in anaesthetized rats while middle ear pressure was increased and then monitored during induced swallowing. Betahistine and other drugs were applied topically in the nasopharynx, bulla and epipharynx, and administered intraperitoneally. Systemic application of betahistine hardly changed eustachian tube function, but topical application significantly improved it. The action of topical betahistine was unaffected by the HI receptor antagonist mepyramine and was mimicked by the H3 agonist, ciproxifan.