The pharmacokinetics of piroxicam in elderly persons with and without renal impairment.

Abstract

1. Piroxicam pharmacokinetics were assessed in three groups of subjects: (1) young healthy volunteers, (2) healthy elderly subjects (mean +/‐ s.d. creatinine clearance 88 +/‐ 13 ml min‐1), and (3) elderly patients with renal insufficiency (creatinine clearance 60 +/‐ 10 ml min‐1) following the administration of piroxicam 20 mg as a single dose and after chronic dosing of 20 mg once daily for 4 weeks. 2. Piroxicam and 5'‐hydroxypiroxicam concentrations were measured by h.p.l.c. in serum and urine samples collected for 96 h after the single dose and for 144 h after chronic dosing. Unbound concentrations of piroxicam were determined by ultrafiltration. 3. Elimination half‐ lives, steady state concentrations of piroxicam and 5'‐ hydroxypiroxicam, clearances of total and unbound piroxicam, volumes of distribution normalized for body weight, and urinary recovery of 5'‐ hydroxypiroxicam were not influenced by age or renal function. Volumes of distribution after the single dose were significantly lower in women compared with men (mean +/‐ s.d. 10.0 +/‐ 2.9 l vs 12.9 +/‐ 5.0 l; 95% confidence interval of the difference 0.1 to 5.6). 4. Percent unbound piroxicam values were 1.46 +/‐ 0.3% after the single dose and 1.45 +/‐ 0.2% at steady state. There were significant reductions in clearance and clearance of unbound piroxicam between single and chronic doses. The half‐lives of 5'‐hydroxypiroxicam (80.9 +/‐ 44 h) were significantly longer than those of piroxicam (54.9 +/‐ 26 h) after chronic dosing. 1994 The British Pharmacological Society