Alexander Cole1, DVM; Adrian Mutlow2, VetMB, MSc; Ramiro Isaza3, DVM, MS, DACZM; James W. Carpenter2, MS, DVM, DACZM; David E. Koch4, MS; Robert P. Hunter4, MS, PhD; Betsy L. Dresser1, PhD
1Center for Research of Endangered Species, Audubon Nature Institute, New Orleans, LA, USA; 2Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA; 3Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA; 4Zoological Pharmacology Laboratory, Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
The pharmacokinetic parameters of carfentanil and naltrexone were determined in the common eland (Taurotragus oryx). Six adult females were immobilized with xylazine (0.23±0.03 mg/kg i.m.) and carfentanil (16.9±0.5 µg/kg i.m.) for a 45-min time period. A single intramuscular injection of naltrexone (1.66±0.08 mg/kg i.m.) was sufficient for reversal. Serial blood samples were collected via jugular venipuncture during and up to 48 hr post immobilization. The quantification of carfentanil and naltrexone in these samples was performed by detection of their metabolites in plasma through liquid chromatography and mass spectroscopy methods. Carfentanil was rapidly absorbed following administration with the peak plasma concentration (Cmax) at 13.8 min. Naltrexone was readily absorbed and reached Cmax at 23.4±16.8 min after administration. All animals stood 2.7±2.2 min (x̄±SD) after naltrexone administration. Carfentanil has a half-life of 7.7 hr, while naltrexone has a much shorter half-life of 3.7 hr. This protocol demonstrated a sufficient depth of anesthesia to perform clinically non-invasive procedures for the duration of the anesthesia with little risk of renarcotization.
This study was supported by a grant from the Morris Animal Foundation.