Istaroxime hydrochloride is a Na + /K + -ATPase inhibitor ( IC 50 =0.11 μM) and a sarcoplasmic/endoplasmic reticulum calcium ATPase 2 ( SERCA 2 ) activator. In Vitro Istaroxime hydrochloride 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. MCE has not independently confirmed the accuracy of these methods. They are for reference only. In Vivo 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. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid IC50& Target:IC50: 0.11 μM (Na + ,K + -ATPase)