A 68-year-old white male with a history of paroxysmal atrial fibrillation, hypertension, and hypercholesterolemia is brought to the physician's office by his daughter because of nausea, anorexia, and confusion. His daughter states that he was admitted at an outside hospital two weeks ago because of uncontrolled hypertension and palpitations. He was started on a new medication. Prior to the recent hospitalization, he was taking digoxin, warfarin, simvastatin, and hydrochlorothiazide. His physical examination shows an irregular heart rate, but is otherwise unremarkable. His blood pressure is 130/80 mmHg, pulse rate is 50/minute and irregular, temperature 37.2C (99F), and respirations are 14/minute. Which of the following is the most likely medication that is contributing to his symptoms?

Question

A 68-year-old white male with a history of paroxysmal atrial fibrillation, hypertension, and hypercholesterolemia is brought to the physician's office by his daughter because of nausea, anorexia, and confusion.  His daughter states that he was admitted at an outside hospital two weeks ago because of uncontrolled hypertension and palpitations.  He was started on a new medication.  Prior to the recent hospitalization, he was taking digoxin, warfarin, simvastatin, and hydrochlorothiazide.  His physical examination shows an irregular heart rate, but is otherwise unremarkable.  His blood pressure is 130/80 mmHg, pulse rate is 50/minute and irregular, temperature 37.2C (99F), and respirations are 14/minute.  Which of the following is the most likely medication that is contributing to his symptoms?

Quizplus · Accepted Answer

Explanation: This patient has developed classic early features of digoxin toxicity. Digoxin toxicity is characterized by nausea, vomiting, anorexia, fatigue, confusion, visual disturbances, and cardiac abnormalities. The most likely explanation of his digoxin toxicity is the recent addition of verapamil. Verapamil inhibits the renal tubular secretion of digoxin, resulting in almost 70-100% increase in serum digoxin levels. The other medications, which can cause digoxin toxicity, are quinidine, amiodarone, and spironolactone. (Choice B) Even though captopril can cause a slight elevation of digoxin levels, the other ACE inhibitors and ARBs usually do not cause digoxin toxicity. (Choice A) Beta-blockers may cause bradycardia when used with digoxin because of the added negative chronotropic action; however, this usually does not result in digoxin toxicity. (Choices C and D)The other medications in the other choices do not cause significant digoxin toxicity. Educational Objective: Verapamil, quinidine, and amiodarone can potentially cause digoxin toxicity.

A 68-Year-Old White Male with a History of Paroxysmal Atrial