The Trimethoprim (TMP) component can act like amiloride in the distal portion of the renal tubule. TMP inhibits the uptake of sodium by the epithelial cell sodium channels in the distal tubule preventing the reabsorption of sodium from the urine but also alters the electrical balance of the tubular cell. As a result the epithelial cell reduces the amount of potassium transported from the cell into the tubular lumen and thus into the urine. The result is a reduction in the amount of potassium…
