Description

Betahistine is a histamine analog that was developed following successful parenteral use of histamine in patients with Meniere's Syndrome. Betahistine relieves vertigo symptoms by improving circulation in the microvasculature of the inner ear which leads to a pressure reduction on the membranous labyrinth and relieves the symptoms of Meniere's disease.

The mechanism of action of betahistine is multifactorial. Meniere's disease is thought to result from a disruption of endolymphatic fluid homeostasis in the ear. Betahistine mainly acts as a histamine H1-receptor agonist. The stimulation of H1-receptors in the inner ear causes a vasodilatory effect leading to increased permeability of blood vessels and a reduction in endolymphatic pressure; this action prevents the rupture of the labyrinth, which can contribute to the hearing loss associated with Ménière's disease. Betahistine is also purported to act by reducing the asymmetrical functioning of sensory vestibular organs and increasing vestibulocochlear blood flow, relieving symptoms of vertigo. In addition to the above mechanisms, betahistine also acts as a histamine H3-receptor antagonist, increasing the turnover of histamine from postsynaptic histaminergic nerve receptors, subsequently leading to an increase in H1-agonist activity. H3-receptor antagonism elevates levels of neurotransmitters including serotonin in the brainstem, inhibiting the activity of vestibular nuclei, thus restoring proper balance and decreasing vertigo symptoms.

The usual initial dose: 8 mg to 16 mg three times daily taken preferably with meals. Maintenance dose: Up to 48 mg daily has been recommended. Betahistine is not recommended for use in children.

There are no proven cases of hazardous interactions. Though an antagonism between Betahistine and antihistamines could be expected on a theoretical basis, no such interactions have been reported.

Betahistine is contraindicated in pheochromocytoma.

Betahistine is generally well tolerated and there is no known serious adverse effects. In some circumstances gastrointestinal disturbances, headache, rashes and pruritus have been reported.

In Pregnancy: The safety of Betahistine in human pregnancy has not been completely established, although there is no known teratogenic effect in animals. A careful assessment of potential benefits should be made before prescribing Betahistine in pregnancy. In Lactation: Betahistine is excreted in the breast milk of nursing mothers in concentrations similar to those found in plasma. Toxicity to the neonate at these concentrations is not known.

Caution should be exercised in patients with bronchial asthma and peptic ulceration.

Drugs used in meniere's diseases