Preparation Of Enrofloxacin Compound Emulsion And Its Pharmacokinetics

Enrofloxacin is the first dedicated animal fluoroquinolones with spectrum bactericidal action, now widely used in the prevention and treatment of animal respiratory tract, gastrointestinal tract and other bacterial infections. This study prepared compound emulsion of enrofloxacin (5%) combined the features of enrofloxacin and aminophylline using single factor test method and orthogonal experimental method, and its preparation and quality was evaluated. Healthy rabbits were used as experimental animals to study the pharmacokinetics of compound emulsion of enrofloxacin in rabbits.The results showed that compound enrofloxacin emulsion was milky white, pH value of8.5±0.2, measured emulsion droplet diameter of about5.0um. The extraction and detection methods were stable with excellent reproducibility for both enrofloxacin and aminophylline. Enrofloxacin of two groups matched two compartment open model, while aminophylline matched two compartment model. For the group receiving compound emulsion of enrofloxacin alone, distribution half-life(t1/2α)and elimination half-life (t1/2β) of enrofloxacin lengthened significantly from (0.249±0.035)h to (0.89±0.102)h and (1.985±0.862)h to (14.256±4.315)h respectively compared with the group receiving commercial injection of enrofloxacin alone. Peak concentration(Cmax) and area under the plasma concentration-time curve(AUC) also increased significantly respectively from(0.566±0.047)h to (1.303±0.126)h and (3.234±0.417)ug.h/ml to (5.195±0.867)ug.h/ml. These changes showed that absorption, distribution and elimination of enrofloxacin with emulsion in rabbits were lengthened significantly respectively, and a significant controlled releasing effect has been achieved for compound emulsion of enrofloxacin as well. The peak concentration(Cmax), area under the plasma concentration-time curve (AUC), distribution half-life(t1/2α), elimination half-life(t1/2β) and Mean Retention Time(MRT) of aminophylline were (5.51±1.05)ug/ml,(32.96±4.04)ug.h/ml,(0.74±0.01)h,(4.07±0.68)h respectively after single intramuscular injection in rabbits. The results showed that the blood concentration of aminophylline within the effective range, while lower than the concentration of aminophylline poisoning.Compound enrofloxacin emulsion was prepared successfully in this study, preliminary evaluation results show that the emulsion preparation was stability, and comply with the requirements of veterinary injectable emulsion. The pharmacokinetic results showed that sustained effect of compound enrofloxacin emulsion was obviously, and had a very good prospects of application in veterinary medicine.