Pharmacology of emesis and gastrointestinal motility: implications for migraine

This paper outlines the physiopharmacology of emesis and its gastrointestinal motor correlates in relation to the possible treatment strategies of a migraine attack. The gastrointestinal motor correlates of vomiting consist of a stereotyped motor response to diverse stimuli and basically include gastric relaxation and a series of events (intestinal motor inhibition and disruption of slow wave activity) in preparation for the occurrence of a retrograde giant contraction that propagates orally and empties intestinal contents into the stomach. These motor correlates always accompany vomiting, but may also appear as an independent phenomenon. Antidopaminergic agents, such as metoclopramide and domperidone, have antiemetic/prokinetic properties, block the gastrointestinal motor correlates of vomiting and may speed up absorption of antimigraine agents. The use of 5-HT4 receptor agonists may be an alternative strategy to achieve prokinesia during a migraine attack, although this issue still needs to be fully addressed by controlled studies. Sumatriptan was found to induce gastric relaxation and delay gastric emptying, but the impact of these effects during a migraine attack remains to be determined.