Most sulfonamides are excreted primarily jn the urine. Bile, feces, milk, and sweat sulfonamides and their metabolites excreted in urine according to their solubilities it can exceeded and leads to crystal formation. This can be prevented by alkalinizing the urine, increasing fluid intake, reducing dose rates in renal insufficiency, and using triplesulfonamide orsulfonamide-diaminopyrimidine combinations.