Noninvasive assessment of the inodilator action of amrinone in healthy man.

The effects of a single dose of 2 mg/kg amrinone (60 min constant rate IV infusion) have been assessed in a double-blind, placebo-controlled, within-subject cross-over study in six healthy volunteers. Combined impedance cardiography, phonocardiography and electrocardiography revealed a protracted drop in mean ventricular ejection time and electromechanical systole together, with a protracted rise in the “contractility” indices dZ/dtmax and the Heather index HI. The profile is compatible with combined venous vasodilation and positive inotropic action. In spite of the methodological constraints, endpoints were reached that were both detectable and relevant. The profiling permitted a better distinction to be made between the possible levels of action than systolic time intervals alone could have done. Therefore, these methods may be of value in the early development of “inodilator” drugs.