A 34-year-old woman with recurrent episodes of vertigo, fluctuating sensorineural hearing loss and tinnitus is diagnosed with Meniere disease. The drug used specifically for this condition acts as a partial H1 receptor agonist and an H3 receptor antagonist, improving inner ear microcirculation. This drug is:
- A Betahistine ✓
- B Meclizine
- C Dimenhydrinate
- D Promethazine
Correct answer: A. Betahistine
Explanation
Betahistine is structurally related to histamine and acts as a weak H1 agonist and a more potent H3 receptor antagonist. H3 blockade increases histamine release from histaminergic neurons, improving vestibular compensation and cochlear blood flow, which reduces the frequency and severity of vertigo attacks in Meniere disease. Meclizine, dimenhydrinate and promethazine are vestibular suppressant antihistamines that treat acute vertigo symptoms but do not modify the underlying disease.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
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