Pharmacokinetics and absolute oral bioavailability of meloxicam in guinea pigs (Cavia porcellus)

Objective To investigate the pharmacokinetics and absolute oral bioavailability of meloxicam in guinea pigs. Study design Prospective crossover study. Animals A group of six healthy male Dunkin Hartley guinea pigs. Methods A single dose of meloxicam (1.5 mg kg(-1)) was administered orally and intravenously (IV) to six healthy male guinea pigs. A wash-out period of 48 hours was taken into account between administrations (oral and IV) in the same animal. Blood was sampled through a central venous catheter before administration (t = 0 hours) and at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 20, 24 and 28 hours post administration. After centrifugation, plasma concentrations of meloxicam were measured by high-performance liquid chromatography with UV detection, and pharmacokinetic parameters were calculated using noncompartmental analysis. Results Meloxicam in guinea pigs exhibited a moderate absorption rate after oral dosing (time to maximal plasma concentration 3.7 +/- 1.7 hours) and maximal plasma concentration was 0.92 +/- 0.30 mg mL(-1). After IV administration, total body clearance and volume of distribution were 0.13 +/- 0.04 and 0.72 +/- 0.36 L kg(-1), respectively. Terminal half-life was 3.7 +/- 0.7 hours and 3.5 +/- 1.1 hours after IV and oral administration, respectively. Body extraction ratio was 0.0087 and mean absorption time was 3.8 +/- 1.7 hours. The absolute oral bioavailability was 0.54 +/- 0.14 in unfasted guinea pigs. Conclusions and clinical relevance This study reported the pharmacokinetics of meloxicam in guinea pigs. Studies concerning efficacy and safety are the next step towards a rational use of this drug in guinea pigs.