Dopexamine hydrochloride, a dopamine analog with specific beta 2 adrenergic and DA1 dopaminergic receptor activity, was evaluated in a prospective study including 20 patients undergoing coronary artery bypass grafting. Shortly after admission to the intensive care unit, increasing doses of dopexamine hydrochloride (1.0, 2.0, 4.0, 6.0, 8.0 and 10.0 micrograms/kg/min) were administered as continuous infusion at 20-minute intervals. Hemodynamic monitoring revealed that dopexamine hydrochloride causes a significant decrease in systemic vascular resistance and a significant increase in cardiac output and heart rate, even at lower dose levels (1.0 micrograms/kg/min). At higher dose levels (greater than or equal to 2.0 micrograms/kg/min), adverse effects such as systolic hypertension and tachycardia were observed. Shunt fraction increased significantly during dopexamine hydrochloride administration, probably due to the increase in cardiac output. It is concluded that dopexamine hydrochloride is a potent vasodilating agent at lower dose levels and is of potential benefit to patients with compromised myocardial function after coronary artery bypass grafting. Higher dose levels may cause unwanted side effects, which might be explained by various mechanisms such as norepinephrine uptake inhibition.