Pharmacokinetics of florfenicol following intravenous and intramuscular doses to cattle |
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Authors: | R. D. LOBELL K. J. VARMA J C JOHNSON R. A. Sams D. F. GERKEN S. M. ASHCRAFT |
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Affiliation: | *Schering-Plough Corporation, Cranford, New Jersey;†Analytica1 Toxicology Laboratory, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA |
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Abstract: | The disposition of florfenicol after single intravenous and intramuscular doses of 20 mg of florfenicol/kg of body weight (b.w.) to feeder calves was investigated. Serum florfenicol concentrations were determined by a sensitive high performance liquid chromatographic method with a limit of quantitation of 0.025 μg/ml. The extent of serum protein binding of florfenicol was only 13.2% at a serum florfenicol concentration of 3.0 μg/ml. Serum concentration-time data after intravenous administration were best described by a triexponential equation. Total body clearance and steady state volume of distribution were 3.75 ml/min/kg b.w. and 761 ml/kg b.w., respectively. The terminal half-life after intravenous administration was 159 min. The absolute systemic availability after intramuscular administration was 78.5% (range: 59.3–106%) and the harmonic mean of the terminal half-life was 1098 minutes, indicating slow release of the florfenicol from the formulation at the intramuscular injection site. |
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