Which medication is associated with hyperkalemia and should be used with caution in HF?

Which medication is associated with hyperkalemia and should be used with caution in HF?

• A. ACE inhibitors
• B. TMP-SMX
• C. Digoxin
• D. Furosemide

Answer: (B)

Hyperkalemia can come from drugs that reduce the kidneys’ ability to waste potassium. Trimethoprim, a component of TMP-SMX, blocks the epithelial sodium channel in the distal tubule, acting like a potassium-sparing diuretic. This decreases potassium excretion in the urine, raising serum potassium levels. In heart failure, patients are often on medications that also raise potassium, such as ACE inhibitors or MRAs, so adding TMP-SMX can significantly increase the risk of dangerous hyperkalemia. That combination is the key teaching point: TMP-SMX is a common non-cardiac drug that can push potassium upward, necessitating careful monitoring or choosing an alternative antibiotic when HF patients require treatment.

Hyperkalemia can come from drugs that reduce the kidneys’ ability to waste potassium. Trimethoprim, a component of TMP-SMX, blocks the epithelial sodium channel in the distal tubule, acting like a potassium-sparing diuretic. This decreases potassium excretion in the urine, raising serum potassium levels. In heart failure, patients are often on medications that also raise potassium, such as ACE inhibitors or MRAs, so adding TMP-SMX can significantly increase the risk of dangerous hyperkalemia. That combination is the key teaching point: TMP-SMX is a common non-cardiac drug that can push potassium upward, necessitating careful monitoring or choosing an alternative antibiotic when HF patients require treatment.