Tissue distribution and elimination of florfenicol in crucian carp (Carassius auratus cuvieri) after a single dose intramuscular or oral administration

Tissue distribution and elimination of florfenicol (FF) in crucian carp were investigated after a single dose (40 mg/kg) of intramuscular (i.m.) or oral gavage (per os; p.o.) administration in freshwater at 25 °C. FF concentrations in tissues (muscle, liver, kidney, gill and bile) were analyzed by means of high-performance liquid chromatography using an ultraviolet detector. Compared to p.o. administration, it took a longer time to reach FF peak concentration (Cmax) in tissues (except for bile) after i.m. administration. The Cmaxs (except for bile) in these tissues were lower, as compared to p.o. administration. The elimination half-lives (t1/2β) in all the tissues (except for bile) were on an average two-fold longer when administered i.m. than administered p.o. Also, the area under the concentration time curve (AUC) and the mean residence time (MRT) was almost two times greater as well in all tissues when administered i.m. than administered p.o. These results indicate that higher levels of FF in tissues were achieved and took a longer time to eliminate the drug when administered i.m. than p.o. In order to achieve effective dosing regimens in crucian carp, the differences in pharmacokinetics should be considered in future studies.