Effect of Age on the Pharmacokinetics of Marbofloxacin Following Intravenous Administration in Calves.

Abstract

The aim of this study was to compare the pharmacokinetics of marbofloxacin after intravenous (IV) administration of a single dose of 10 mg/kg to calves of different ages. The study was carried on 1- (n = 6), 2- (n = 6), and 4-month-old (n = 6) Montofon calves. Plasma concentrations of marbofloxacin were measured using HPLC, and pharmacokinetic data were calculated by non-compartmental analysis. The elimination half-life (t_1/2ʎz), volume of distribution at steady state (V_dss), total clearance (Cl_T), and area under the concentration-versus time curve (AUC_0-∞) values of marbofloxacin in 1-month-old calves were 10.62 h, 1.03 L/kg, 0.08 L/h/kg, and 127.90 h*μg/mL, respectively. While the t_1/2ʎz (from 10.62 to 3.36 h) and AUC_0-∞ (from 127.90 to 47.35 h*μg/mL) decreased in parallel with the age of the calves, Cl_T (from 0.08 to 0.21 L/h/kg) increased. The V_dss of marbofloxacin was higher in 1- and 2-month-old calves compared to 4-month-old calves. After IV administration of marbofloxacin at a dose of 10 mg/kg, an ƒAUC_0-24/MIC₉₀ ratio of ≥ 125 was obtained for bacteria with MIC₉₀ values of ≤ 0.60, ≤ 0.39 and ≤ 0.27 μg/mL in 1-, 2-, and 4-month-old calves, respectively. These results show that the antibacterial effect of marbofloxacin, which has concentration-dependent activity, decreases due to age-related pharmacokinetic changes and that the 10 mg/kg dose should be reviewed according to the MIC₉₀ value of the bacteria.