The influence of amitriptyline and flunarizine on catecholamine response to light in patients with migraine

The effect of amitriptyline on catecholamine (CA) response to light of 20 migrainous patients was studied. The drug was given orally, 36 mg daily (12 mg x 3), for ten days. Before therapy, the migraineurs responded to light by an increase in epinephrine (E) excretion and not by the rise in norepinephrine (NE) excretion, noticed in controls. The NE excretion of migrainous subjects underwent very often a depression after photostimulation. Amitriptyline therapy prevented the post-photic rise in E excretion of migraineurs, without influencing significantly the variation in NE excretion produced in them by light. In other 8 migrainous subjects the effect of flunarizine, a selective calcium channel blocker, on CA response to light was tested. The dosage was of 5 mg daily, for ten days. Flunarizine had similar effects to those displayed by amitriptyline; the drug prevented the rise in E excretion produced by light without normalizing the NE response to light of migrainous subjects. The results suggest that the efficiency of these two drugs in migraine prophylaxis is connected with the ability of these substances to block the E discharge produced in migraineurs by light or by other stimuli. The interpretation is all the more likely as propranolol, another drug applied in migraine prophylaxis also blocks the post-photic E discharge of migraineurs.