Why should quinidine be avoided in patients receiving digoxin therapy?

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It displaces digoxin from its tissue binding locationsIt displaces digoxin from plasma protein binding sitesIt reduces the renal elimination of digoxinIt lowers potassium levels in the bloodstream

Explanation

Quinidine interacts with digoxin by displacing it from its tissue binding sites, which can increase digoxin's free concentration and risk of toxicity. This is the primary reason quinidine should be avoided in patients on digoxin. Other options, such as displacing protein binding or affecting potassium levels, are not the main concerns in this interaction.