Cardiac Glycosides

Digoxin is the cardiac glycoside most likely to appear in bedside medication questions. It is useful only when several pieces of information are considered together: the pulse and rhythm, renal function, electrolytes, symptoms, dose timing, and recent medication changes. This is a narrow-therapeutic-index drug. A patient can receive the same prescribed dose for months and then become toxic after dehydration, acute kidney injury, intensified diuretic therapy, or addition of an interacting medication. The safest nurse does not treat the medication administration record as the whole clinical picture. Digoxin also holds two apparently opposing effects at once. It strengthens myocardial contraction, yet slows impulse formation and conduction through the sinus and atrioventricular nodes. That combination explains both its selected therapeutic uses and many of its dangerous adverse effects.