Influence of three coccidiostats on the pharmacokinetics of florfenicol in rabbits

In-feed Medication has been used for a long time to prevent coccidiosis, a worldwide protozoal disease in rabbits. Florfenicol (FFC) has been widely used in veterinary clinics for bacterial diseases treatment. Therefore, the use of combinations of coccidiostats with FFC in rabbits is common. In the present study, we aimed to evaluate the effect of three coccidiostats, sulfaquinoxaline (SUL), robenidine (ROB), and toltrazuril (TOL), as feed additives on the pharmacokinetic profile of FFC in rabbits. The disposition kinetics of FFC in rabbits were investigated after a single intravenous injection (25 mg/kg) in rabbits fed anticoccidial-free diets or feeds containing SUL (250 ppm), ROB (66 ppm), or TOL (2 ppm), respectively, for 20 days. Plasma FFC concentrations were determined by the high performance liquid chromatography (HPLC) method. The pharmacokinetic parameters of FFC were analyzed using a non-compartmental analysis based on the statistical moment theory. The results demonstrated that ROB feeding resulted in an obvious decrease in plasma FFC level as compared with anticoccidial-free feeding. The terminal elimination half-life (t1/2z), area under the concentration-time curve (AUC), area under the first moment curve (AUMC), and mean residence time (MRT) significantly decreased, whereas the elimination rate constant (λz) and total body clearance (CLz) obviously increased in rabbits pretreated with ROB. However, we did not find that SUL or TOL feeding had any effect on the pharmacokinetic profile of FFC. Our findings suggested that more attention should be paid to the use of FFC in rabbits supplemented with ROB.