Istaroxime inhibits the Na+/K+-ATPase activity from the dog kidney (IC50: 0.43 ± 0.15 μM). Istaroxime acting as a positive inotropic compound through the inhibition of the Na+, K+-ATPase[2]. Inhibition of Na+/K+-ATPase activity in preparations from guinea pig kidney yielded potencies of 8.5 μM for PST2744[3].

Istaroxime (PST2744) causes a progressive to enhance in +dP/dtmax throughout the infusion. That reaches 80% (ED80) at the cumulative dose of 1.89±0.37 mg/kg and a peak of 140±3.5% at the dose (EDmax) of 4.88±0.6 mg/kg[3].