Intravenous pirbuterol.

Pirbuterol was given intravenously to nine normal men to determine the hemodynamic effects of intravenous injection of this rather selective beta 2-adrenoceptor agonist. Pirbuterol induced marked improvement of the echocardiographic (percent change in the dimension of the minor axis of the left ventricle during systole, ejection fraction, and velocity of left ventricular circumferential fiber shortening) and systolic time interval (preejection period interval, preejection period/left ventricular ejection time) indices of ventricular performance. The increase in stroke volume was indicated by elevation of systolic blood pressure and widening of pulse pressure. Vascular beta 2-receptor agonist effects were indicated by the fall in diastolic and mean systemic blood pressure and marked reduction in derived systemic vascular resistance. Dose-related positive chronotropic properties were observed without dysrhythmias. There was a good direct correlation between mean plasma pirbuterol concentration and dose. Because of the reported efficacy of oral doses, the direct relationship between plasma concentration and dosage, the positive inotropic properties, and the peripheral vasodilating effects of pirbuterol, investigation of the intravenous form of the drug in patients with severe decompensated low-output congestive heart failure seems warranted.