ICD-10 Specific code T75.3: Motion sickness

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.

Cyclizine is a histamine H₁ receptor antagonist of the piperazine class which is characterised by a low incidence of drowsiness. It possesses anticholinergic and antiemetic properties. The exact mechanism by which cyclizine can prevent or suppress both nausea and vomiting from various causes is unknown.

Dimenhydrinate is a theoclate salt of the ethanolamine derivative diphenhydramine. It exhibits reversible competitive antagonism with histamine for the capture of H1 receptors. It has anticholinergic (antimuscarinic) properties that explain the anti-emetic action of the drug in cases of labyrinthial irritation (nausea, vertigo), and the central suppression it causes.

Diphenhydramine is an ethanolamine-derivative antihistamine. It is an antihistamine with anticholinergic and marked sedative effects. It acts by inhibiting the effects on H₁-receptors. Diphenhydramine is effective in reducing sleep onset (i.e., time to fall asleep) and increasing the depth and quality of sleep.

Meclizine is a first generation antihistamine that is used largely to treat vertigo and motion sickness.