Hyperkalemia Associated With High‐Dose Trimethoprim‐Sulfamethoxazole in a Patient With the Acquired Immunodeficiency Syndrome

Abstract

When given in standard dosages to treat bacterial respiratory and urinary tract infections, trimethoprim‐sulfamethoxazole (TMP‐SMX) is not commonly associated with hyperkalemia. However, the emergence of the acquired immunodeficiency syndrome has led to increased numbers of patients with Pneumocystis carinii pneumonia (PCP) who require high‐dose TMP‐SMX therapy. A 25‐year‐old man with human immunodeficiency virus infection developed hyperkalemia while receiving high‐dose TMP‐SMX for PCP. His baseline serum potassium of 3.0 mEq/L, which increased to 4.2 mEq/L after potassium replacement therapy, rose to 6.9 mEq/L after 8 days of TMP‐SMX. No other etiology was found for the hyperkalemia, and the disorder resolved when TMP‐SMX was stopped. It recurred when the patient was rechallenged with high doses of TMP‐SMX during a second treatment course for PCP. This case and a review of previous reports highlight the importance of monitoring serum potassium concentrations in patients receiving high‐dose TMP‐SMX. 1995 Pharmacotherapy Publications Inc.