Betahistine is first-line drug therapy for definite Meniere's disease. Its principal pharmacological action relevant to reducing endolymphatic pressure is:

• A Potent H2 receptor blockade with suppression of gastric acid secretion
• B H3 receptor antagonism that increases release of endogenous histamine, acting on H1 receptors to improve inner ear microcirculation ✓
• C Direct vestibular hair cell ablation similar to aminoglycosides
• D Central cerebellar inhibition identical to cinnarizine

Explanation

Betahistine is a structural analogue of histamine acting as a strong H3 receptor antagonist and weak H1 receptor agonist. Blocking presynaptic H3 autoreceptors increases hypothalamic histamine release, and stimulation of H1 receptors on inner ear vasculature improves labyrinthine microcirculation and promotes resorption of endolymph in the sac. It does not destroy hair cells, which is the domain of intratympanic gentamicin, nor is its primary action central like cinnarizine.

Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.