Pharmacokinetics of Meloxicam in Healthy Donkeys

Meloxicam, a non-steroidal anti-Inflammatory drug (NSAID), has been reported as a safe substitute for diclofenac which was banned for veterinary use during 2005-06, due to its relay toxicity associated with the catastrophic decline in vulture populations in Indian subcontinent. It is a preferential cyclooxygenase-2 (COX-2) inhibiter with higher therapeutic index as compared to diclofenac, indomethacin and piroxicam. The pharmacokinetics of meloxicam was studied in donkeys. Eight donkeys used in the experiment were administered 0.6 mg.kg body weight as an intravenous bolus of meloxicam through jugular vein. Blood samples (5ml) were drawn pre medication and then up to 96 h post-medication. Plasma concentrations of meloxicam were measured in triplicate by HPLC. The plasma concentration versus time profile was prepared. Mean (+SEM) values of pharmacokinetic parameters viz., area under curve, steady state volume of distribution, half-life, mean residence time and clearance were 6.017±0.009 μg.h/ml, 0.136±0.002 L/kg, 1.002±0.008 h, 1.404±0.053 h and 0.094±0.002 L/h/kg, respectively. These pharmacokinetic parameters of meloxicam in donkeys were comparable to the reported values in donkeys but different from those of other species like sheep, goats, horses, chicken, rabbits and rats. A fast elimination with short half life and higher clearance are suggestive that current dosage regimens of meloxicam may not be clinically effective in donkeys and further research is recommended.