Evaluation of allometric scaling as a tool for extrapolation of the enrofloxacin dose in American black vultures (Coragyps atratus).

OBJECTIVE: To determine the pharmacokinetics of enrofloxacin after IV administration in American black vultures (Coragyps atratus), to compare clearance of enrofloxacin in American black vultures with clearance of this fluoroquinolone in other avian species, and to evaluate whether allometric scaling is an appropriate tool for dose extrapolation in avian species. ANIMALS: 6 healthy adult American black vultures. PROCEDURES: Enrofloxacin concentrations were quantified by use of high-performance liquid chromatography. Pharmacokinetics of enrofloxacin was determined in American black vultures after IV administration. Pharmacokinetic parameters for 12 avian species obtained from 24 pharmacokinetic studies were used. Allometric analysis of enrofloxacin pharmacokinetic parameters was performed. RESULTS: Volume of distribution at steady state for enrofloxacin was 3.47 L/kg, clearance was 0.147 L/h·kg, and elimination half-life was 18.3 hours. Comparisons among avian species revealed that American black vultures had the lowest extraction ratio for enrofloxacin (1.04%). Only the volume of distribution at steady state and clearance had a good allometric fit. Goodness of fit was improved when ratites were not included in the analysis. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that the use of allometric scaling for the prediction of volume of distribution at steady state could provide a suitable method for extrapolation of enrofloxacin doses among avian species; however, allometric scaling could not be used to adequately predict the clearance of enrofloxacin.

Comparison of pharmacokinetics of marbofloxacin after subcutaneous administration of various multiple-dose regimens to water buffalo calves (Bubalus bubalis).

OBJECTIVE: To determine pharmacokinetics of marbofloxacin in water buffalo calves (Bubalus bubalis) after multiple SC administrations and to assess differences in regimen efficacy. ANIMALS: 18 healthy buffalo calves. PROCEDURES: Calves (n = 6 calves/group) were assigned to receive marbofloxacin SC in the neck at 1 of 3 dosages (2 mg/kg, q 24 h for 6 days [regimen 1]; 4 mg/kg, q 48 h for 6 days [regimen 2]; and 4 mg/kg, q 24 h for 3 days [regimen 3]). Serum marbofloxacin concentrations were analyzed. Efficacy predictors were estimated on the basis of minimum inhibitory concentration and mutant prevention concentration reported for Pasteurella multocida and Mannheimia haemolytica. RESULTS: Mean ± SD area under the concentration-time curve was 5.92 ± 0.40 µg•h/mL for regimen 1, which differed significantly from that for regimens 2 (14.26 ± 0.92 µg•h/mL) and 3 (14.17 ± 0.51 µg•h/mL). Mean residence time and mean elimination half-life for regimen 2 (9.93 ± 0.20 hours and 8.77 ± 0.71 hours) both differed significantly from those for regimens 1 (721 ± 0.11 hours and 5.71 ± 0.38 hours) and 3 (759 ± 0.13 hours and 737 ± 1.19 hours). Values obtained from indices for P multocida and M haemolytica had an excessively wide range because of the various degrees of antimicrobial susceptibility (low, medium, and high) of the strains. CONCLUSIONS AND CLINICAL RELEVANCE: Regimen 3 had the most favorable indices, and it would be conducive for owner compliance and require less handling of animals.

The pharmacokinetic behaviour of marbofloxacin in Eurasian buzzards (Buteo buteo) after intraosseous administration.

This study reports on the administration of a single dose of marbofloxacin (2 mg/kg) to five adult Eurasian buzzards (Buteo buteo) by the intraosseous (IO) route, which has been proposed as a rapid and efficient means for the parenteral delivery of antimicrobial drugs. The drug was rapidly absorbed. Peak marbofloxacin concentration (C(max)) in plasma and area under the concentration-time curve (AUC) of 1.92+/-0.78 microg/mL and 8.53+/-2.73 microg h/mL, respectively. The time marbofloxacin remained in the plasma after IO administration was relatively short (elimination half-life, t(1/2beta)=4.91+/-0.65 h; mean residence time (MRT)=5.38+/-0.57 h). Single dose marbofloxacin gave values for C(max)/minimum inhibitory concentration (MIC) of 19.2 and an AUC/MIC value of 85.3h after IO administration. The IO route appears to be practical and effective for the rapid delivery of marbofloxacin to buzzards.

Hematologic, protein electrophoresis, biochemistry, and cholinesterase values of free-living black stork nestlings (Ciconia nigra).

Hematologic, protein electrophoresis, serum biochemistry, and cholinesterase values were determined in 36 free-living black stork nestlings (Ciconia nigra) between 25 and 53 days of age in order to establish normal reference values for this population. The following values were evaluated: white blood cell counts, red blood cell counts, packed cell volume, hemoglobin, heterophils, lymphocytes, monocytes, eosinophils, prealbumin, albumin, alpha-globulin, beta-globulin, gamma-globulin, total protein, aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase, creatine kinase, calcium, phosphorus, iron, cholesterol, glucose, triglycerides, uric acid, urea, creatinine, total solids, bile acids, and butyrylcholinesterase. Sex-dependent differences were observed in hemoglobin, prealbumin, albumin, gamma-globulin, total protein, alkaline phosphatase, and triglycerides. Packed cell volume, butyrylcholinesterase, aspartate aminotransferase, creatine kinase, and creatinine increased with age, whereas albumin, mean cell volume, calcium, phosphorus, cholesterol, and total solids decreased with age. These hematologic and serum biochemistry values can be used as reference ranges in free-living black stork nestlings.