A Pharmacokinetic Comparison of Meloxicam and Ketoprofen following Oral Administration to Healthy Dogs

Abstract

Ketoprofen (KTP) and meloxicam (MLX) are non-steroidal anti-inflamatory drugs used extensively in veterinary medicine. The pharmacokinetics of these drugs were studied in eight dogs following a single oral dose of 1 mg/kg of KTP as a racemate or 0.2 mg/kg of MLX. The concentrations of the drugs in plasma were determined by high-performance liquid chromatography (HPLC). There were differences between the disposition curves of the KTP enantiomers, confirming that the pharmacokinetics of KTP is enantioselective. (S)-(+)-KTP was the predominant enantiomer; the S:R ratio in the plasma increased from 2.58±0.38 at 15 min to 5.72±2.35 at 1 h. The area under the concentration–time curve (AUC) of (S)-(+)-KTP was approximately 6 times greater than that of (R)-(–)-KTP. The mean (±SD) pharmacokinetic parameters for (S)-(+)-KTP were characterized as T _max = 0.76±0.19 h, C _max = 2.02±0.41 μg/ml, t $t_{\frac{1}{2}{\text{el}}}$ = 1.65±0.48 h, AUC = 6.06±1.16 μg.h/ml, V _d/F = 0.39±0.07 L/kg, Cl/F = 170±39 ml/(kg.h). The mean (±SD) pharmacokinetic parameters of MLX were T _max = 8.5±1.91 h, C _max = 0.82±0.29 μg/ml, t $t_{\frac{1}{2}\lambda ({\text{z)}}}$ = 12.13±2.15 h, AUC_inf = 15.41±1.24 μg.h/ml, V _d/F = 0.23±0.03 L/kg, and Cl/F = 10±1.4 ml/(kg.h). Our results indicate significant pharmacokinetic differences between MLX and KTP after therapeutic doses.