 Reference Base  Pharmacokinetics of a single oral dose of flunixin meglum... |
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Captive |
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Diseases |
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White Rhino |
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Appropriate analgesia for colic, lameness, osteoarthritis management, and other medical conditions in white rhinoceroses (Ceratotherium simum) is critical. Flunixin meglumine is one of the most common non-steroidal anti-inflammatories used for analgesia in megavertebrates but its pharmacokinetics in rhinoceroses have not been published.2 Due to this lack of data, equine pharmacokinetic and pharmacodynamic data are commonly used for dosing rhinoceroses.
However, there are dangers in extrapolating drug doses when limited species-specific
pharmacokinetic information exists.1,3 Adult white rhinoceroses (n = 5) were administered flunixin megluminea (1 mg/kg, p.o.). Blood samples were collected from each animal at pre-determined time points after drug administration. Plasma flunixin and 5-OH flunixin concentrations were determined, and pharmacokinetic analysis was performed using industry standard software.b Mean maximum plasma concentrations (Cmax) of 1207 ± 601 ng/ml were reached at an average of 3 hr. The geometric mean apparent elimination half-life was approximately 8.3 h ± 1.2 hr. Phase I metabolite 5-hydroxy flunixin concentrations averaged 10% of flunixin concentration for most of the time points. These data demonstrate important differences in drug disposition from horses: one study reported mean Cmax of 2500 ng/ml, which is approximately twice the concentrations found in this study, and an apparent elimination half-life of 1.5 hr, which is considerably shorter than estimated in this study.4 Our results support that oral flunixin meglumine (1 mg/kg) may provide therapeutic drug concentrations in white rhinoceroses based on efficacy data in other species.5 Further studies are necessary to investigate long-term safety and efficacy after multiple doses of flunixin meglumine in this species.
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