Digitoxin is a cardenolide glycoside in which the 3beta-hydroxy group of digitoxigenin carries a 2,6-dideoxy-beta-D-ribo-hexopyranosyl-(1->4)-2,6-dideoxy-beta-D-ribo-hexopyranosyl-(1->4)-2,6-dideoxy-beta-D-ribo-hexopyranosyl trisaccharide chain. It has a role as an EC 3.6.3.9 (Na(+)/K(+)-transporting ATPase) inhibitor. It derives from a digitoxigenin. It is a conjugate acid of a digitoxin(1-). Digitoxin appears as odorless white or pale buff microcrystalline powder. It is a cardiac glycoside sometimes used in place of digoxin. It has a longer half-life than digoxin; toxic effects, which are similar to those of digoxin, are longer lasting. 

Pharmacodynamics

Digitoxin is a cardiac glycoside sometimes used in place of DIGOXIN. It has a longer half-life than digoxin; toxic effects, which are similar to those of digoxin, are longer lasting . It is eliminated hepatically making it useful in patients with poor or erratic kidney function, although it is now rarely used in practice. Digitoxin lacks the strength of evidence that digoxin has in the management of heart failure.

Mechanism of action

Digitoxin inhibits the Na-K-ATPase membrane pump, resulting in an increase in intracellular sodium and calcium concentrations. Increased intracellular concentrations of calcium may promote activation of contractile proteins (e.g., actin, myosin). Digitoxin also acts on the electrical activity of the heart, increasing the slope of phase 4 depolarization, shortening the action potential duration, and decreasing the maximal diastolic potential.