Pharmacokinetics of meloxicam following intramuscular, subcutaneous, and oral administration in white storks (Ciconia ciconia)

Abstract

Meloxicam (MLX) is a preferential cyclooxygenase-2 inhibitor widely used in avian medicine as an anti-inflammatory agent. Despite marked interspecific variability in avian drug disposition, no pharmacokinetic data are available for MLX in the white stork ( Ciconia ciconia ). This study aimed to characterise and compare the plasma pharmacokinetics of MLX in this species. Six clinically stable, non-releasable white storks (three of each sex) received a single 1 mg/kg dose of MLX by the IM, SC and PO routes in a randomised three-way crossover design with a 2-week washout period between treatments. Plasma MLX concentrations were quantified up to 24 h using HPLC and analysed using non-compartmental methods. Peak plasma concentrations (C max ) differed significantly among all three routes (IM 11.49 ± 2.34, SC 6.43 ± 1.62, PO 1.53 ± 0.89 µg/mL; p  < 0.05) and the median time to peak concentration (tmax) was progressively delayed from IM (0.67 h) through SC (2.00 h) to PO (4.00 h). Systemic exposure did not differ significantly between the IM and SC routes (AUC 0–24 h 80.7 ± 40.2 and 81.1 ± 22.7 µg·h/mL, respectively) and approximately 7-fold greater than after PO administration (11.9 ± 4.8 µg·h/mL; p  < 0.05), corresponding to relative bioavailabilities versus IM of 100.4% for SC and 14.8% for PO. Terminal half-life progressively increased from IM (9.81 ± 2.30 h) through SC (15.13 ± 4.41 h) to PO (18.85 ± 2.16 h). SC administration may represent a practical parenteral alternative to IM, whereas PO administration displayed low and variable bioavailability in white storks.