Amrinone: pharmacokinetics and pharmacodynamics.

Amrinone is a selective inhibitor of phosphodiesterase fraction 3 in both cardiac and smooth muscle. Intravenous administration in humans produces increased contractility and vasodilation of venous capacitance and arterial conductance vessels. The elimination half-life in healthy patients is reported to be 2.6 to 4.1 hours, making it the only long-acting positive inotropic agent available that can be administered either as an intravenous bolus or by infusion. A low incidence of side effects, often minor, has been reported with intravenous use. Thrombocytopenia does not seem to be a problem with short-term use. Amrinone represents a new approach in the pharmacologic therapy for ventricular dysfunction following cardiac surgery.