Which medication in the elderly woman’s chart is most likely responsible for digoxin toxicity through electrolyte disturbance?

Which medication in the elderly woman’s chart is most likely responsible for digoxin toxicity through electrolyte disturbance?

• A. Furosemide
• B. Ramipril
• C. Bisoprolol
• D. Spironolactone

Answer: (A)

Electrolyte disturbances can amplify digoxin toxicity by changing how digoxin interacts with the Na+/K+ ATPase in heart cells. When potassium or magnesium levels drop, digoxin binds more readily to this enzyme, increasing its effects and the risk of dangerous arrhythmias. A loop diuretic like furosemide causes loss of potassium and magnesium in the urine, leading to hypokalemia and hypomagnesemia that predispose to digoxin toxicity. In an elderly patient, reduced renal function can further raise digoxin levels, but the key link is the electrolyte loss from the loop diuretic. Spironolactone raises potassium, ramipril can cause hyperkalemia, and bisoprolol doesn’t create the same electrolyte disturbances that promote digoxin toxicity.

Electrolyte disturbances can amplify digoxin toxicity by changing how digoxin interacts with the Na+/K+ ATPase in heart cells. When potassium or magnesium levels drop, digoxin binds more readily to this enzyme, increasing its effects and the risk of dangerous arrhythmias. A loop diuretic like furosemide causes loss of potassium and magnesium in the urine, leading to hypokalemia and hypomagnesemia that predispose to digoxin toxicity. In an elderly patient, reduced renal function can further raise digoxin levels, but the key link is the electrolyte loss from the loop diuretic. Spironolactone raises potassium, ramipril can cause hyperkalemia, and bisoprolol doesn’t create the same electrolyte disturbances that promote digoxin toxicity.