Pharmacology Of Digitoxin

Indication	For the treatment and management of congestive cardiac insufficiency, arrhythmias and heart failure.
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 (From Martindale, The Extra Pharmacopoeia, 30th ed, p665). Unlike digoxin (which is eliminated from the body via the kidneys), it is eliminated via the liver, so could be used in patients with poor or erratic kidney function. However, it is now rarely used in current UK medical practice. While there have been several controlled trials which have shown digoxin to be effective in a proportion of patients treated for heart failure, there is not the same strong evidence base for digitoxin, although it is presumed to be similarly effective.
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.
Absorption	Not Available
Volume of distribution	Not Available
Protein binding	Not Available
Metabolism	Hepatic.
Route of elimination	Not Available
Half life	Not Available
Clearance	Not Available
Toxicity	Digitoxin exhibits similar toxic effects to the more-commonly used digoxin, namely: anorexia, nausea, vomiting, diarrhoea, confusion, visual disturbances, and cardiac arrhythmias.