The nurse is caring for a client who was admitted with new onset palpitations who takes prescribed digoxin at home. What additional medication on the medication reconciliation would lead the nurse to assess the client for upset stomach and green-yellow vision disturbances.

Choice A rationale Metformin is an oral biguanide anti-hyperglycemic agent used to manage type 2 diabetes mellitus by decreasing hepatic glucose production and improving insulin sensitivity in peripheral tissues. It does not typically interact with digoxin to cause enhanced toxicity or visual/gastrointestinal symptoms like those described; common side effects are usually gastrointestinal in nature, such as diarrhea or nausea. Its use would not inherently increase the risk of digoxin-related adverse effects. Choice B rationale Nitroglycerin is an organic nitrate medication primarily used to treat and prevent angina pectoris by causing vasodilation, which decreases myocardial oxygen demand and increases blood flow. It has no known significant pharmacokinetic or pharmacodynamic interaction with digoxin that would lead to increased serum levels or enhanced toxicity, thus it does not cause green-yellow visual disturbances or gastrointestinal upset. Choice C rationale Furosemide is a potent loop diuretic that causes the excretion of sodium, chloride, and potassium. Hypokalemia, a common side effect of furosemide, potentiates digoxin toxicity by reducing the activity of the sodium-potassium pump, allowing more digoxin binding. This interaction can precipitate classic signs of toxicity, including nausea, vomiting (upset stomach), and visual changes like green-yellow halos. Normal potassium range is 3.5 to 5.0 mEq/L. Choice D rationale Warfarin is an anticoagulant that works by inhibiting vitamin K-dependent clotting factors, and is used to prevent thromboembolic events. Although Warfarin has many drug interactions, it does not typically interact with digoxin to increase its serum concentration or toxicity risk in a way that causes the specific gastrointestinal and visual symptoms noted. There is no direct significant pharmacodynamic interaction leading to enhanced digitalis effect.