Abstract
Over 70% of captive elephants in North America have musculoskeletal problems,3 and flunixin meglumine (Banamine®; Merck Animal Health, Madison, NJ 07940, USA) is the most commonly used nonsteroidal anti-inflammatory drug.2 However, no pharmacokinetic study for flunixin has been conducted in elephants, and dosages used range widely.2 Pharmacokinetic parameters of flunixin were determined in 16 African (Loxodonta africana) and Asian (Elephas maximus) elephants after single-dose oral administration of 0.8 and 1.5 mg/kg flunixin. After administration of 0.8 mg/kg flunixin, mean serum concentrations peaked in approximately 1.5 h at 2.1±0.76 µg/ml for Asian (n=8) and 3 h at 2.5±0.65 µg/ml for African (n=8) elephants. Dosages of 1.5 mg/kg flunixin resulted in mean serum concentration peaks of 7.2±1.47 µg/ml and 4.6±0.61 µg/ml approximately 1.5 h post-administration in Asian elephants (n=7) and African elephants (n=5), respectively (p<0.004). The area of the first moment curve was significantly greater in Asian (693.8±292.67 h2*µg/ml) compared to African elephants (305.9±99.10 h2*µg/ml) (p<0.02), and the harmonic mean half-life was longer in Asian compared to African elephants (10.2±3.35 h versus 7.2±2.45 h, respectively), although differences were not significant. Flunixin is excreted primarily via hepatic routes with small amounts in the urine. Asian elephants may engage in some level of enterohepatic recycling of flunixin, as was previously reported for phenylbutazone.1 Multiple-dose trials are currently underway, and slightly different treatment regimens for Asian and African elephants will likely be recommended using 1.1 mg/kg flunixin orally.
Acknowledgments
The authors are grateful to the keepers and staff at the facilities who participated in this study to date, including the Center for Elephant Conservation, African Lion Safari, Zoo Miami, Grant‘s Farm, The Maryland Zoo in Baltimore, Fresno Chaffee Zoo, Jacksonville Zoo and Gardens, Virginia, Caldwell Zoo, and Cleveland Metroparks Zoo. We also thank the Kansas City Zoo for participating in a pilot study.
Literature Cited
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