Pharmacokinetics of multiple doses of chloramphenicol in fed adult horses

Publication date: Available online 21 February 2020Source: The Veterinary JournalAuthor(s): K.E. Estell, H.K. Knych, T. Patel, J.M. Edman, K.G. MagdesianAbstractTo the authors’ knowledge, there have been no studies evaluating the pharmacokinetics of chloramphenicol administered orally to horses at the currently recommended dose of 50 mg/kg PO q 6 h for multiple days. The published antimicrobial susceptibility breakpoint is 8.0 ug/mL; it is unknown if this concentration is achievable at the recommended dose rate in horses. The aim of this prospective multi-dose pharmacokinetic study was to perform pharmacokinetic analysis of chloramphenicol after multiple doses. The authors hypothesize that the antimicrobial susceptibility breakpoint will not be reached. Seven healthy adult horses were administered 50 mg/kg chloramphenicol base tablets PO q 6 h for 4 days. Blood was collected via venipuncture daily at 4 and 6 h after administration for the first 15 doses. After the 16th dose, an IV catheter was aseptically placed in the right jugular vein and blood was collected at regular intervals for pharmacokinetic analysis.Maximum chloramphenicol concentration was variable between horses (2.1-42.7 μg/mL). The highest average chloramphenicol concentration was just below the susceptibility breakpoint at 7.7 ug/mL while the lowest was well below the breakpoint at 1.5 ug/mL. On average, the time above 8.0 μg/mL was 75 min, considerably less than the recommended 50% of the ...
Source: The Veterinary Journal - Category: Veterinary Research Source Type: research