Cardiac glycoside
Cardiac glycosides are drugs used in the treatment of congestive heart failure (CHF) or cardiac arrhythmia, by inhibiting the Na+/K+ pump. This inhibition increases the amount of Ca++ ions available for contraction and improves cardiac output and reduces distention of the heart.
Cardiac glycosides are extracted from plant material :
- strophantus - ouabaine
- digitalis lanata and digitalis purpurea - digoxin, digitoxin
- scilla maritima - proscillaridine A
It has an antiarrhythmic effect by prolonging the refractory period of the AV node (Atrio-ventricular), reducing the number of impulses reaching the ventricles. Cardiac output is restored but atrial fibrillation or atrial flutter are not abolished.