Anatomical Therapeutic Chemical Classification System
Betahistine dihydrochloride is a histamine-like drug in which pharmacological activity can be attributed to a specific effects and/or more direct influences on recovery mechanisms the vestibular nuclei. It has weak agonist activity at histamine H1 receptors and moderate antagonist activity at H3 receptors. Betahistine may increase blood flow to the cochlear region as well as to the whole brain.
Cinnarizine has been shown to be a non-competitive antagonist of the smooth muscle contractions caused by various vasoactive agents including histamine. Cinnarizine also acts on vascular smooth muscle by selectively inhibiting the calcium influx into depolarised cells, thereby reducing the availability of free Ca2+ ions for the induction and maintenance of contraction.
Flunarizine is a selective calcium entry blocker with calmodulin binding properties and histamine H1 blocking activity. It is effective in the prophylaxis of migraine, occlusive peripheral vascular disease, vertigo of central and peripheral origin, and as an adjuvant in the therapy of epilepsy.