Sulfate Homeostasis. III. Effect of Chronic Naproxen or Sulindac Treatment on Inorganic Sulfate Disposition in Arthritic Patients with Renal Impairment

The purpose of the present investigation was to examine the influence of chronic naproxen (500 mg twice daily) or sulindac (200 mg twice daily) therapy on the disposition of inorganic sulfate in arthritic subjects with impaired renal function. Subjects were studied during a control period (after a 7-day NSAID washout) and after 14 days of treatment with either naproxen or sulindac. During the control period subjects in this investigation exhibited higher serum sulfate concentrations and lower sulfate renal clearance values than reported for younger subjects with normal renal function. Treatment with either sulindac or naproxen significantly decreased creatinine clearance. Sulindac therapy also increased the serum sulfate concentration and decreased the clearance of sulfate; a similar trend was observed after naproxen therapy but the average change was smaller and not statistically significant. There were significant correlations between the creatinine and the sulfate clearances or serum concentrations. The glomerular filtration rate of inorganic sulfate was not altered by drug treatment and there was no impairment of reabsorption. The serum concentrations and renal clearance of other electrolytes (sodium, potassium, magnesium, calcium, phosphorus) were largely unaffected. Therefore, chronic treatment with naproxen or sulindac decreases the renal clearance of endogenous sulfate in humans: this appears to be a consequence of the decrement in renal function observed in subjects with preexisting mild renal impairment.