Clinical use of trimethoprim/sulfamethoxazole during renal dysfunction

This article reviews the pharmacokinetics, clinical use, and adverse effects of trimethoprim/sulfamethoxazole (TMP/SMX) in renally impaired patients. Renal dysfunction changes the pharmacokinetics of both component drugs. TMP and SMX disposition are not significantly altered until creatinine clearance is less than 30 mL/min, when SMX metabolites and TMP accumulate and may lead to toxicity. Renal dysfunction, however, does not preclude the use of TMP/SMX to treat susceptible infections, even when creatinine clearance is less than 15 mL/min. Adverse effects may occur more frequently in renally impaired patients but are not clearly related to increased serum concentrations of either drug. Guidelines for appropriate dosing and monitoring of TMP/SMX therapy in these patients are presented.