Article: PDF OnlyTRIMETHOPRIM IS A POTASSIUM-SPARING DIURETIC LIKE AMILORIDE AND CAUSES HYPERKALEMIA IN HIGH-RISK PATIENTSPerazella, Mark A.Author Information Section of Nephrology, Department of Medicine, Yale University school of Medicine, New Haven, CT, USA. American Journal of Therapeutics: September 1997 - Volume 4 - Issue 9 - p 343 Buy Abstract Trimethoprim-sulfamethoxazole is a commonly prescribed antimicrobial agent. Twenty-five years after its introduction into clinical practice, an unrecognized and potentially lethal adverse reaction associated with trimethoprim-sulfamethoxazole therapy, hyperkalemia, was described. Both “high-dose” and “standard-dose” trimethoprim-sulfamethoxazole have been associated with this electrolyte disorder. Recognition of this potassium disturbance led to the subsequent description of the mechanism by which trimethoprim-sulfamethoxazole induced hyperkalemia. Trimethoprim was found to act like the potassium-sparing diuretic amiloride and reduce renal potassium excretion. Hence, trimethoprim is in fact a potassium-sparing diuretic like amiloride and causes hyperkalemia in high-risk patients. © Williams & Wilkins 1997. All Rights Reserved.