In older adults with atrial fibrillation or heart failure, the recommended maximum daily dosage for digoxin when used in older adults is:

• A. 0.125 mg/day or less
• B. 0.25 mg/day
• C. 0.5 mg/day
• D. 1 mg/day

Answer: (A)

In older adults, the safest approach to digoxin is the smallest effective dose because aging often brings reduced kidney function and greater sensitivity to the drug, both of which raise the risk of toxicity with even modest amounts. The Beers criteria and common practice recommend a maximum daily dose of one-eighth of a milligram (0.125 mg) or less to minimize toxicity while still providing benefit for atrial fibrillation or heart failure. Higher daily doses, such as a quarter of a milligram or more, markedly increase the risk of adverse effects like bradycardia, confusion, GI symptoms, and visual changes, especially in those with renal impairment or electrolyte disturbances. In some cases, clinicians tailor the dose further based on renal function, sometimes stretching the interval between doses to avoid accumulating too much drug.