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.