The consequences of osmotic diuresis in residual nephrons for urinary drug excretion.

The renal clearance of chloramphenicol (calculated per 100 ml of inulin clearance) increased in linear relation to fractional sodium and water excretion. The renal excretion of chloramphenicol may be influenced by changes in fractional water excretion without changes in fractional sodium excretion. The low sodium diet did not significantly change chloramphenicol urinary excretion in patients with chronic renal insufficiency. The results obtained are compatible with the view that osmotic diuresis in residual nephrons, the development of which is in part accounted for by an adaptive decrease in tubular sodium reabsorption, affects urinary excretion of drugs, the tubular transport of which depends on fractional water reabsorption.