DOPAMINE-D2 RECEPTOR BLOCKADE AND ANTIMIGRAINE ACTION OF FLUNARIZINE

We studied in vivo the influence of flunarizine on dopamine D2 recepto rs and investigated whether dopamine D2 receptor blockade is involved in its antimigraine action. Eleven migraine patients, treated with flu narizine, 10 mg per day, underwent single photon emission computer tom ography (SPECT) using [I-123] labeled iodobenzamide, a ligand with hig h affinity and high specificity for D2 receptors. There was a reductio n of the dopamine D2 receptor binding potential in all patients compar ed to age-matched controls. The efficacy of flunarizine in migraine pr ophylaxis failed to correlate with the degree of the dopamine D2 recep tor blockade. The antimigraine action of flunarizine may not involve a ntidopaminergic mechanisms.