Pharmacokinetics of a florfenicol-tylosin combination after intravenous and intramuscular administration to beagle dogs.

A pharmacokinetic study of a commercial florfenicol-tylosin (2:1) combination product was conducted in six beagle dogs after intravenous (IV) and intramuscular (IM) administration at doses of 10 mg/kg (florfenicol) and 5 mg/kg (tylosin). Serum drug concentrations were determined by a validated high performance liquid chromatography (HPLC) using UV detection. A rapid and nearly complete absorption of both drugs with a mean IM bioavailability of 103.9% (florfenicol) and 92.6% (tylosin), prolonged elimination half-life, and high tissue penetration with steady state volume of distribution of 2.63 l/kg (florfenicol) and 1.98 l/kg (tylosin) were observed. Additional studies, including pharmacodynamic and toxicological evaluation are required before recommendations can be made regarding the clinical application of the product in dogs.