Ruthie A. Parsley1, BS, BA; Adrian G. Mutlow2, MA, VetMB, MSc, MRCVS; Jacqueline Jencek2, DVM; Hung T. Kieu1, BS; Scott E. Wetzlich1, BS; Lisa A. Tell1, BS, DVM, DABVP (Avian), DACZM
Aspergillosis is a common cause of illness and mortality in captive penguins.3 Voriconazole (Vfend™; Pfizer Pharmaceuticals, New York, NY) is a second-generation triazole drug with broad spectrum antifungal activity, including against Aspergillus spp.6,7 Avian voriconazole pharmacokinetic studies are limited1,2,5,8,10 and there are no published studies for penguins.
Fifteen adult Magellanic penguins (Spheniscus magellanicus) were given a single oral dose of 2.5 mg/kg voriconazole in a fish. Blood samples were taken at 0.5, 1, 2, 4, 8, 12, and 24-hours post administration. Each bird was bled a maximum of three times in a 24-hour period. Ultra-performance liquid chromatography was used as previously described to measure plasma concentrations.4 Data points for each time point were averaged for non-compartmental analysis. Mean plasma concentrations were above the targeted minimum inhibitory concentration (MIC=1.0 µg/ml)9 for a short time (0.6 hours) and the long mean elimination half-life (15.1 hours) indicated potential for drug accumulation with multiple doses.
Further studies using higher- and multiple-dose administration are needed before making therapeutic dosage recommendations. In addition, it is important to note that the targeted MIC is based on in vitro susceptibility patterns and it is not known how in vitro susceptibilities correlate with therapeutic efficacy in birds. However, using this preliminary information, an adult penguin with confirmed aspergillosis responded favorably (resolution of both clinical signs and leukocytosis) to a voriconazole treatment cycle of 5 mg/kg SID for five days, then one day off treatment. The day-off treatment helped prevent signs of suspected drug accumulation (anorexia).
This study was supported by funding from the California Department of Fish and Game’s Oil Spill Response Trust Fund through the Oiled Wildlife Care Network at the Wildlife Health Center and the STAR program, School of Veterinary Medicine, University of California, Davis. The authors thank the San Francisco Zoo bird department staff for their assistance with this project.
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