Non-vascular action of calcium blockers in migraine: pupillopharmacological study

A pupillopharmacological study has been carried out to evaluate the influence of two calcium blockers (CBs), flunarizine and nimodipine, on iris neurotransmission in migraine patients. Pretreatment with an oral dose of flunarizine or nimodipine markedly decreased the mydriasis induced by instillation of tyramine, a noradrenaline releaser. On the contrary, both drugs did not change the mydriasis by conjunctival phenylephrine, a postsynaptic adrenoceptor stimulant. In addition, nimodipine abolished the miosis caused by echothiophate iodide eye drops, a putative releaser of substance P from trigeminal sensory nerve endings. These findings suggest the idea that CBs treatment in migraine syndromes acts at presynaptic level by attenuating calcium-dependent release of monoaminergic and peptidergic neurotransmitters.