IC50: 0.11 μM (Na ⁺ ,K ⁺ -ATPase)

Istaroxime acting as a positive inotropic compound through the inhibition of the Na ⁺ ,K ⁺ -ATPase. Istaroxime (PST2744) inhibits the Na ⁺ /K ⁺ -ATPase activity from dog kidney with an IC ₅₀ value of 0.43 ± 0.15 μM. Inhibition of Na ⁺ /K ⁺ -ATPase activity in preparations from guinea pig kidney yielded potencies of 8.5 μM for PST2744.

Istaroxime (PST2744) induces a progressive increase in +dP/dt _max throughout the infusion that reaches 80% (ED ₈₀ ) at the cumulative dose of 1.89±0.37 mg/kg and a peak of 140±3.5% at the dose (ED _max ) of 4.88±0.6 mg/kg.