Recent developments in tachykinin NK1 receptor antagonists: prospects for the treatment of migraine headache.

The role of substance P and the influence of neurokinin 1 (NK1) receptor antagonists in the cranial circulation are described in the present review, particularly with respect to the mechanisms involved in the etiology of migraine headache. Substance P is distributed throughout the cranial vasculature, in the trigeminal sensory afferent nerve fibres, and its release can be demonstrated following activation of the trigeminovascular system in animals and humans. Following its release and NK1 receptor activation, dilatation and edema result, two events that are implicated in the pathogenesis of migraine headache. The recently developed selective NK1 receptor antagonists inhibit substance P mediated dilatation and plasma protein extravasation in the cranial circulation, suggesting that they may provide an effective and novel acute treatment for migraine.