Sustained hemodynamic effects of the selective dopamine-1 agonist, fenoldopam, during 48-hour infusions in hypertensive patients: a dose-tolerability study.

Eight patients with stage I-II hypertension received a continuous IV infusion of the selective dopamine-1 agonist, fenoldopam, for up to 48 hours at rates from 0.4 to 1.9 micrograms/kg/min. Hemodynamics and clinical symptoms during infusion were compared to the same parameters in the 24-hour periods before and after infusion. Fenoldopam lowered blood pressure and increased heart rate. Greatest changes occurred during the first 12 hours of infusion and gradually returned toward preinfusion values throughout the remaining 36 hours in the six patients who completed 48 hours of infusion. Fenoldopam was discontinued within 2 hours of starting the infusion in two patients who received drug rates of 0.9 microgram/kg/min and 1.9 micrograms/kg/min because of precipitous bradycardia. Clinical symptoms noted at fenoldopam doses higher than 0.8 microgram/kg/min were headache, dizziness, diaphoresis, nausea and vomiting, and restlessness. In this pilot study, fenoldopam effectively reduced blood pressure in patients with stage I-II hypertension for up to 48 hours, but fixed-dose infusion rates above 0.8 microgram/kg/min were associated with a high frequency of clinically significant and often intolerable adverse effects.