Which of the following medications is a cardiac glycoside that can cause hyperkalemia?

Digoxin is a well-known cardiac glycoside that is primarily used to treat heart conditions such as atrial fibrillation and heart failure. One of the pharmacological effects of digoxin is the inhibition of the sodium-potassium ATPase pump in cardiac myocytes, which leads to an increased intracellular concentration of calcium. This enhances the force of myocardial contraction (positive inotropic effect) but also influences potassium levels within the body.

Hyperkalemia, or elevated potassium levels in the blood, can occur with digoxin use, particularly in situations where there is renal impairment or when digoxin is used in conjunction with other medications that also raise potassium levels. The risk of hyperkalemia is clinically significant because elevated potassium can lead to cardiac complications and arrhythmias, making monitoring required during digoxin therapy.

In contrast, the other medications listed serve different functions. Lisinopril is an ACE inhibitor that primarily affects blood pressure and can cause hyperkalemia but is not classified as a cardiac glycoside. Spironolactone is a potassium-sparing diuretic that can also lead to hyperkalemia but operates through a different mechanism. Telmisartan is an angiotensin II receptor blocker (ARB) that likewise may cause increases in potassium levels