Effects of indomethacin and methylprednisolone on renal elimination of lithium in the rat.

Wistar rats were given lithium chloride (16.7 mg/kg i.p.) after treatment with indomethacin (2.5 mg/kg/day for 5 days), with methylprednisolone (3 mg/kg/day for 5 days), or with their solvents. Lithium and creatinine clearance and urinary elimination of sodium and phosphate were determined. Indomethacin increases while methylprednisolone decreased the fractional tubular reabsorption of lithium. The quantity of lithium eliminated in the urine is correlated with the urinary elimination of sodium and phosphate. The effects of the anti-inflammatory drugs on renal elimination of lithium seemed linked to their effects on proximal sodium reabsorption.