Many commonly used drugs interact with digitalis compounds. The Class IA antiarrhythmic, quinidine, competes with digoxin for binding sites and depresses renal clearance of digoxin.
Similar interactions occur with calcium-channel blockers and nonsteroidal anti-inflammatory drugs.
Diuretics can indirectly interact with digoxin because of their potential for decreasing plasma potassium levels (i.e., producing hypokalemia).
Therapeutic Uses of Digitalis Compounds
↑ ejection fraction
↓ pulmonary congestion/edema
↓ AV nodal conduction
↓ ventricular rate in atrial flutter