[Effect of combined therapy with selective beta 1- and alpha 1-adrenergic agonists upon postprandial hypotension in patients with progressive autonomic failure].

Food ingestion increases mesenteric blood flow, and then results in a decrease of total vascular resistance (VR). Postprandial hypotension (PPH) may be caused by a lack of compensatory increase in cardiac output (CO) together with a lack of reflex peripheral vasoconstriction to the decrease in total VR. In order to increase CO and VR, we orally administered both denopamine 10 mg (a selective beta 1-adrenergic agonist) and midodrine HCl 4 mg (a selective alpha 1-adrenergic agonist) to six patients with progressive autonomic failure (AF). PPH was well prevented by concomitant administration of both denopamine and midodrine HCl 30 min before oral ingestion of 75 g of glucose, i.e., CO and portal blood flow as well as VR in the lower legs increased. These hemodynamic reactions after oral ingestion of 75 g of glucose were very similar to those in the control subjects. The marked increase in heart rate after drug administration may be the result of cardiac supersensitivity in patients with AF. Combined oral administration of both denopamine and midodrine HCl is a safe and useful management of PPH in patients with AF.