From the FDA Drug Label
Angiotensin Converting Enzyme Inhibitors Avoid concurrent use In the literature, three cases of hyperkalemia in elderly patients have been reported after concomitant intake of sulfamethoxazole and trimethoprim and an angiotensin converting enzyme inhibitor
- Key Interaction: Sulfamethoxazole and trimethoprim should be avoided with angiotensin converting enzyme inhibitors due to the risk of hyperkalemia.
- Clinical Decision: Avoid concurrent use of sulfamethoxazole 400 mg-trimethoprim 80 mg tablet with Benicar 20 mg tablet, an angiotensin receptor blocker related to angiotensin converting enzyme inhibitors, to minimize the risk of hyperkalemia 1.
From the Research
Patients taking sulfamethoxazole 400 mg-trimethoprim 80 mg tablet with Benicar 20 mg tablet should be closely monitored for hyperkalemia, as the combination of these medications can increase the risk of high potassium levels and potentially affect kidney function. Sulfamethoxazole-trimethoprim is an antibiotic used to treat various infections, while Benicar is an angiotensin II receptor blocker used to treat high blood pressure. The interaction occurs because both medications can affect potassium levels in the body - trimethoprim reduces potassium excretion by the kidneys, and Benicar can also lead to potassium retention 2.
Key Considerations
- Patients taking this combination should ensure adequate hydration, monitor for symptoms of high potassium (muscle weakness, irregular heartbeat, tingling sensations), and have their kidney function and potassium levels checked periodically 3.
- This is particularly important for older adults and those with existing kidney problems, as they are at higher risk of developing hyperkalemia 4.
- The mechanism of trimethoprim-induced hyperkalemia is thought to be related to the competitive inhibition of epithelial sodium channels in the distal nephron, similar to the potassium-sparing diuretic amiloride 5.
- Hyperkalemia can occur even in patients with normal renal function, highlighting the importance of monitoring potassium levels in all patients taking this combination 3.
Monitoring and Prevention
- Patients should be educated on the signs and symptoms of hyperkalemia and instructed to seek medical attention immediately if they experience any of these symptoms.
- Healthcare providers should regularly monitor potassium levels and kidney function in patients taking this combination, especially in high-risk populations.
- In cases where hyperkalemia occurs, discontinuation of the medication and treatment with potassium-lowering therapies may be necessary 6.