What does calcium do to digoxin?

What does calcium do to digoxin?

• A. Increases toxicity
• B. Decreases toxicity
• C. No effect
• D. Depends on dose

Answer: (A)

Calcium increases digoxin toxicity due to how digoxin alters calcium handling in heart cells. Digoxin inhibits the Na+/K+ ATPase, which raises intracellular sodium and reduces the Na+/Ca2+ exchanger’s ability to remove calcium. This leads to more intracellular calcium and stronger, prolonged contraction. If calcium levels are elevated, there’s even more calcium inside the cells, which can trigger afterdepolarizations and dangerous arrhythmias in the presence of digoxin. Because of this proarrhythmic potential, administering calcium to a patient on digoxin can precipitate toxicity, so calcium can worsen digoxin’s toxic effects.

Calcium increases digoxin toxicity due to how digoxin alters calcium handling in heart cells. Digoxin inhibits the Na+/K+ ATPase, which raises intracellular sodium and reduces the Na+/Ca2+ exchanger’s ability to remove calcium. This leads to more intracellular calcium and stronger, prolonged contraction. If calcium levels are elevated, there’s even more calcium inside the cells, which can trigger afterdepolarizations and dangerous arrhythmias in the presence of digoxin. Because of this proarrhythmic potential, administering calcium to a patient on digoxin can precipitate toxicity, so calcium can worsen digoxin’s toxic effects.