Pharmacokinetics of Buprenorphine Hydrochloride in American Kestrels (Falco sparverius) Following IM And IV Administration
American Association of Zoo Veterinarians Conference 2013
Kate Gustavsen1, PhD, DVM; David Sanchez-Migallon Guzman1, LV, MS, DECZM (Avian), DACZM; Heather Knych2, DVM, PhD, DACVCP; Olivia Petritz3, DVM; Joanne Paul-Murphy1, DVM, DACZM, DACAW
1Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA, USA; 2Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA; 3William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, CA, USA


Opioids are the most effective class of analgesic drugs for management of moderate to severe pain. Based on the results of previous studies, kappa opioid receptor agonist drugs have been used predominantly in birds.4,5,7,8 However, recent studies have shown that the mu agonists fentanyl and hydromorphone may have analgesic properties in raptors.2,3,6 Buprenorphine is a semi-synthetic partial mu opioid receptor agonist; in mammals it has a long-lasting, moderate analgesic effect and high margin of safety.1 Preliminary data using a thermal stimulus in American kestrels (Falco sparverius) suggests that buprenorphine has analgesic properties in this species (Guzman, unpublished data). In the study reported here, the pharmacokinetics of buprenorphine hydrochloride following IM and IV administration were determined in kestrels (n=16) in a complete crossover design, with a 2-week washout period. Blood was collected from 3 or 4 birds at each of 9 time points, from 5 minutes to 9 hours. Plasma buprenorphine concentrations were measured by liquid chromatography–mass spectrometry, and pharmacokinetic parameters were determined using non-compartmental analysis. After IV administration, the steady-state volume of distribution was 4,024 mL/kg, with a clearance of 49 mL/kg/min and an elimination half-life of 105 minutes. After IM administration, bioavailability was 94.5%, with a maximum plasma concentration of 243 ng/mL at 5 minutes and an elimination half-life of 93 minutes. IM administration of buprenorphine hydrochloride to American kestrels results in rapid absorption, high bioavailability, and similar kinetics to IV administration.

Literature Cited

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Speaker Information
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Kate A. Gustavsen, PhD, DVM
Department of Medicine and Epidemiology
School of Veterinary Medicine
University of California
Davis, CA, USA

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