Antibiotic-Induced Hyperkalemia and Renin-Angiotensin–System Inhibitors

Recent years have seen greatly increased use of renin-angiotensin system inhibitors, including angiotensin-converting–enzyme inhibitors and angiotensin-receptor blockers. With this increase, we should expect a rise in novel drug interactions.

Knowing that hyperkalemia has been associated both with renin-angiotensin–system inhibitors and with trimethoprim, investigators in Toronto performed a population-based, nested case-control study among older patients (aged ≥66) who were receiving continuous treatment with one of these blockers and had also been prescribed trimethoprim-sulfamethoxazole (TMP-SMX), ciprofloxacin, norfloxacin, nitrofurantoin, or amoxicillin. Cases (371 patients who were hospitalized between 1994 and 2008 for treatment of hy…