Hypertensive crisis induced by metoclopramide in patient with pheochromocytoma.

A hypertensive crisis associated with evidence of catecholamine release was induced following intravenous administration of 10 mg metoclopramide in a woman with pheochromocytoma and in whom the tyramine test was negative. After removal of the tumor, blood-pressure and plasma catecholamine concentrations were not influenced by the administration of metoclopramide. It is suggested that the mechanism of hypertensive crises induced by metoclopramide may not be due to a direct catecholamine releasing effect from the tumor or sympathetic nerve endings, but rather to its presynaptic dopaminergic blocking effect which would indirectly release catecholamines.