Pharmacokinetics of tenoxicam in patients with impaired renal function.

The pharmacokinetics of tenoxicam after a single oral dose of 20 mg has been studied in 12 patients with various degrees of decreased renal function. Unchanged tenoxicam and its 5'OH-metabolite in plasma and urine were determined by HPLC. The mean areas under the plasma concentration-time curve (138 +/- 53 micrograms/ml X h) and terminal half-lives in patients with impaired renal function did not differ from values previously reported in normal volunteers, nor did the peak concentration of tenoxicam. The half-life of 5'OH-tenoxicam and unchanged tenoxicam where the same. The urinary excretion of 5'OH-tenoxicam fell with decreasing renal function. Thus no dosage adjustment should be necessary and the usual daily dose of tenoxicam may be administered once daily also to patients with renal failure.