Name: Digoxin (Lanoxin)
Class: CHF Rx (Cardiac Glycoside)
Mechanism: Inhib. of Na+/K+ ATPase ® release of Ca2+ from SR ® myocardial contractility. Also sensitivity of AV node to vagal stimulation ® ¯ ventricular rate in atrial flutter or fibrillation (i.e., anti-arrhythmic).
Absorption:
Dist.:
Metabolism.: Very little.
Excretion, t½: Urine. Short t½.
Toxicity/S.E.s: Low therapeutic index. Toxicity enhanced by hypokalemia. Arrhythmias (possibly life-threatening), anorexia, n/v/d, drowsiness, fatigue, visual disturbances. Verapamil or quinidine ® toxicity.
Utility: Treat heart failure. DOC for atrial fibrillation/flutter.
Special Features: No active Metabolismolites. Shorter t½, less GI absorption, and less protein binding than digitoxin. Only cardiac glycoside routinely used.