Cardiac glycosides or digitalis essentially refer to a group of chemically and pharmacologically related drugs, that act on the heart by causing atrioventricular conduction and vagal tone.
They are invariably employed to slow the heart rate in atrial fibrillation and also administered in congestive heart failure.
A large number of ‘drug substances’ are able to enhance the force of contraction of the heart. It is, however, pertinent to state here that this ionotropic activity may be specifically of great utility and importance in the ultimate treatment of congestive heart failure
Drugs originally obtained from plant source, Digitalis purpurea and Digitalis lanata
Main pharmacologic effect of cardiac glycosides is to increase the contractile force of myocardial contraction
Cardiac glycosides also decrease heart rate and atrioventricular conduction
The side chain of digoxin is made up of three molecules of digitoxose in a glycosidic linkage, which upon hydrolysis yields the aglycone, digoxigenin (C23 H34 O5).
Digoxigenin is obtained from the leaves of Digitalis lanata Ehrh. (Family : Scrophulariaceae). Its cardiotonic actions are very much alike to those of digitalis. It is used in the treatment of congestive heart failure
Digitoxin is obtained from Digitalis purpurea Linne, Digitalis lanata Ehrh, and other suitable species of Digitalis.
Its side chain is comprised of three molecules of digitoxose in a glycosidic linkage. Hydrolysis affects removal of the side chain to yield the aglycone, digitoxigenin (C23H34O4).