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ABSTRACT 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-1 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.
Keywords: NSAIDs, diclofenac toxicity, meloxicam, pharmacokinetics, donkeys.
INTRODUCTION Non-steroidal anti-inflammatory drugs (NSAIDs) are frequently prescribed and commonly used in humans, as well as in animals, to reduce pain, fever and inflammation for the treatment of different clinical conditions such as rheumatic disorders (Huskisson et al., 1996). It has been established scientifically that relay toxicity of diclofenac was responsible for dramatic fall in vulture population within Indian subcontinent. Vultures were exposed to diclofenac when they had consumed carcasses of livestock that were treated with this drug, before death. Residual diclofenac in the dead livestock animal had caused death as it had elevated uric acid concentrations in serum causing visceral gout leading to kidney failure of vulture This commonly available NSAID was extensively used in veterinary practice in south asia as an analgesic and anti inflammatory agent (Prakash et al., 2003; Green et al., 2004).
However, diclofenac was banned for veterinary use in Pakistan, India and Nepal during 2005-06, following evidence of its role...