Urinary Excretion and Plasma Levels of Sulphonamides in Patients with Renal Impairment

Abstract

Summary Urine and plasma levels and the clearance of two sulphonamides have been studied in patients with varying degrees of renal failure. In patients with renal impairment there is a decreased sulphadiazine clearance and a reduced 24 hour excretion after a single intravenous dose of sulphadiazine. In 4 patients on 7 occasions on continuous sulphadiazine or sulphamethizole therapy for three days there was an accumulation in the plasma of free and conjugated sulphonamide. In three of these patients elevated sulphonamide levels were associated with toxic side effects. Urine concentrations of free sulphonamide were much reduced in patients with renal impairment. Low urine concentrations and high plasma levels limit the use of sulphonamides in patients with renal damage.