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Pharmacology: Pharmacodynamics: ANTI-VERTIGO PREPARATIONS.
(N: central nervous system).
Betahistine's mechanism of action is partly known.
In vitro: betahistine facilitates histaminergic transmission due to its partial agonist effect on H1 receptors and the antagonist effect of H3 receptors. Betahistine reduces the electrical activity of the polysynaptic neurones of vestibular nuclei after I.V. administration to animals. Betahistine does not have a sedative effect.
Pharmacokinetics: Betahistine is rapidly and completely absorbed following administration via the oral route.
Food intake significantly reduces betahistine absorption without amending the quantities absorbed.
It is eliminated in the urine in the form of a metabolite: 2-pyridyl acetic acid.
The elimination half-life is approximately 3.5 hours.
Elimination is virtually complete in 24 hours.
