THE NOVEL ANTIMIGRAINE AGENT RIZATRIPTAN INHIBITS NEUROGENIC DURAL VASODILATION AND EXTRAVASATION

These studies in anaesthetised rats showed, using intravital microscop y, that the novel anti-migraine agent, rizatriptan, significantly redu ced electrically stimulated dural vasodilation but had no effect on in creases in dural vessel diameter produced by exogenous substance P or calcitonin gene-related peptide (CGRP). Rizatriptan also significantly inhibited dural plasma protein extravasation produced by high intensi ty electrical stimulation of the trigeminal ganglion. We suggest that rizatriptan inhibits the release of sensory neuropeptides from perivas cular trigeminal nerves to prevent neurogenic vasodilation and extrava sation in the dura mater. These prejunctional inhibitory effects may b e involved in the anti-migraine action of rizatriptan.