Comparative Pharmacokinetics of Enrofloxacin and Tissue Concentrations of Parent Drug and Ciprofloxacin after Intramuscular Administrations of Free and Liposome-Encapsulated Enrofloxacin in Rabbits

Summary Pharmacokinetic properties and tissue concentrations of enrofloxacin and ciprofloxacin were compared after intramuscular (i.m.) administrations of free and liposome‐encapsulated enrofloxacin at the dose of 5 mg/kg body weight (bw). Twelve healthy adult New Zealand white rabbits were used in the experiment. Blood samples were obtained at 10, 20, 40, 60 and 90 min and 2, 4, 6, 8 and 12 h and tissue samples were collected 24 h after injection. Concentrations of drugs in serum were determined by high‐performance liquid chromatography. Pharmacokinetics were best described by a two‐compartment open model. Results indicated that absorption rate was slow, peak concentration was higher (P