Pharmacokinetic Profiles of Enrofloxacin and Its Metabolite Ciprofloxacin Administered by Different Doses in Calves

This research studied dose-dependent changes in the pharmacokinetics of enrofloxacin (ENR) and its active metabolite, ciprofloxacin (CIP), in calves. The research was performed on eighteen calves utilizing a parallel pharmacokinetic approach. Calves were divided into three distinct dosage groups, receiving intravenous administration of ENR at doses of 2.5, 5, and 10 mg/kg, respectively. Blood samples were collected at 15 specified intervals during a 48-h duration. ENR and CIP plasma concentrations were quantified by HPLC. Pharmacokinetic data was obtained using non-compartmental analysis. The area under the concentration-time curve from 0 to last (AUC0-last)/dose of ENR increased in a dose-dependent manner. The elimination half-life of ENR was prolonged from 2.41 to 3.47 h (p < 0.05). The total body clearance decreased significantly with the dose increase (p < 0.05), while the volume of distribution at steady state remained comparable across dosage groups (p > 0.05). The AUC0-last of CIP increased in a dose-dependent manner (p < 0.05), but no alteration was found in the conversion ratio of ENR to CIP (26%–28%, p > 0.05). The results of the current investigation demonstrated that the pharmacokinetics of ENR and CIP in calves had considerable variability with dose. Assessing dose-dependent pharmacokinetic alterations in calves can aid in establishing the dosing regimen; however, additional research is required to confirm dose-dependent therapeutic efficacy and safety.