&NA;Dapitant (RPR 100893) is a selective nonpeptide perhydroisoindolone derivative with antagonist activity at neurokinin (NK)1 receptors. NK1 receptors are thought to mediate the neurogenic inflammatory effects of substance P. The related compound, RP 67580, is also a selective substance P antagonist and has been shown to block neurogenic extravasation in the dura mater after electrical or chemical trigeminal stimulation.Dapitant has shown promise as an antimigraine agent in several animal models, with >100-fold higher potency than sumatriptan, dihydroergotamine or aspirin (acetylsalicylic acid) with respect to inhibition of dural neurogenic inflammation. Dapitant is currently in phase II clinical trials with Rhône-Poulenc Rorer in France as an oral therapy for migraine and pain.