Digoxin

Use caution in chronic constrictive pericarditis, electrical cardioversion, severe bradycardia, severe heart failure, severe pulmonary disease, sick sinus syndrome, ventricular tachycardia, ventricular premature contractions, Wolff-Parkinson-White syndrome, electrolyte imbalance, hypothyroidism or hyperthyroidism, hypoxia, idiopathic hypertrophic subaortic stenosis, renal disease, concomitant diuretics

Not recommended in patients with acute myocardial infarction

Avoid in patients with myocarditis

Risk of advanced or complete heart block in patients with sinus node disease and AV block

Very narrow margin between effective therapeutic and toxic dosages: Therapeutic range, 0.5-2 ng/mL (target 0.5-1 ng/mL); toxic range, >2.5 ng/mL

Generally avoid if left ventricular systolic function preserved, although may be used for ventricular rate control in subgroup with chronic atrial fibrillation

Less effective in presence of hypokalemia or hypocalcemia; avoid hypercalcemia or hypomagnesemia, which may predispose to serious arrhythmias

Heart failure patients with preserved ventricular function, including acute cor pulmonale, amyloid heart disease, and constrictive pericarditis may be susceptible to digoxin toxicity

May cause false-positive ST-T changes during exercise testing

Do not switch between different PO forms or between brand and generic forms of digoxin; bioavailability varies

Serum levels drawn within 6-8 hours of dose will be falsely high because of prolonged distribution phase

Increased risk of estrogen-like effects in geriatric patients

Beriberi heart disease may not respond adequately if underlying thiamine deficiency not corrected

Atrial arrhythmias are difficult to treat if associated with hypermetabolic (hyperthyroidism) or hyperdynamic (hypoxia) states; treat underlying condition before initiating therapy