What should be avoided if the patient is on Digoxin/Lanoxin?

• A. Calcium Chloride
• B. Potassium chloride
• C. Sodium bicarbonate
• D. Magnesium sulfate

Answer: (A)

Calcium-containing therapies should be avoided in patients taking digoxin because of a dangerous interaction that can precipitate digitalis toxicity and dangerous arrhythmias. Digoxin inhibits the Na+/K+-ATPase pump, which already raises intracellular calcium in heart cells. Giving additional calcium (like calcium chloride) further increases intracellular calcium, amplifying digoxin’s effects and raising the risk of life-threatening arrhythmias. That’s why calcium chloride is the choice to avoid.

Potassium chloride isn’t avoided for this reason; maintaining normal potassium helps reduce digoxin toxicity, since hypokalemia can enhance digoxin’s effects. Sodium bicarbonate and magnesium sulfate aren’t the classic avoid-at-all-costs interactions with digoxin in the same way calcium is, so they’re not singled out for avoidance in this scenario.