The pharmacokinetic disposition and bioavailability of florfenicol (FF) were determined after single intravenous (i.v.) and intramuscular (i.m.) administrations of 25 mg/kg b.w. to ten healthy New Zealand White rabbits. Plasma FF concentrations were determined by high-performance liquid chromatography (HPLC). The plasma pharmacokinetic values for FF were best described by a one-compartment open model. The elimination half-life (t(1/2 beta)) was different (p < 0.05) however, the area under curve (AUC) was similar (p > 0.05) after i.v. and i.m. administrations. FF was rapidly eliminated (t(1/2 beta) 1.49 +/- 0.23 h), slowly absorbed and high (F, 88.75 +/- 0.22%) after i.m. injection. In addition, FF was widely distributed to the body tissues (V-ss 0.98 +/- 0.05 L/kg) after im. injection. In this study the time that plasma concentration exceeded the concentration of 2 mu g/mL was approximately 6 h. For bacteria with MIC of 2 mu g/mL, frequent administration at this dose would be needed to maintain the concentration above the MIC. However, it is possible that rabbit pathogens may have MIC values less than 2 mu g/mL which would allow for less frequent administration. Further studies are necessary to identify the range of MIC values for rabbit pathogens and to identify the most appropriate PK-PD parameter needed to predict an effective dose. Crown Copyright (C) 2008 Published by Elsevier Ltd. All rights reserved.