The digitalis glycosides are the only orally active positive inotropic agents currently available. The positive inotropic occurs through inhibition of the enzyme Na⁺-K⁺-ATPase leading to an increase in the cytocyclic Ca²⁺ concentration resulting in a subsequent increase in previously reduced myocyte contraction (Hurst). It reduces heart rate via parasympathomimetic effects that is useful in enhancing ventricular filling and reduces pulmonary congestion.