Piroxicam Plasma Concentrations Following Repeated Topical Application of a Piroxicam 0.5% Gel

Abstract

The pharmacokinetic parameters of a piroxicam 0.5% topical gel were determined in 20 healthy volunteers (6 women and 14 men) following application of multiple doses (20mg piroxicam daily) over 14 days. 21 blood samples were drawn from each patient beginning just before application of the first dose, with the final sample taken 14 days after application of the last dose. Plasma concentrations of piroxicam were determined by high-performance liquid chromatography using UV detection at 340nm. There was considerable interindividual variation in piroxicam half-lives with a mean of 79 hours. Mean piroxicam plasma concentrations at steady-state were between 300 and 400 ng/ml, which is about 5% of those observed after equivalent doses of oral or intramuscular piroxicam. No adverse experiences were reported during the study period. Thus, the results of this study confirm the minimal systemic absorption of piroxicam during multiple-dose application of the 0.5% topical gel and the excellent tolerability of this mode of piroxicam therapy.