Preparation Of A Sustained-Release Enrofloxacin Hydrogel Using Chitosan And Poly(Lactic-Co-Glycolic Acid) Polymers

Objectives: The short half life of conventional enrofloxacin preparations limits its proper usage for livestock antimicrobial therapy, since it is difficult to manage therapeutic course when the number of farm animals is high. To overcome this problem, this study was aimed to develop a sustained-release formulation that remains liquid when stored at 4ºC but forms a gel, in minimum time when injected or the temperature was raised to 37ºC. Materials and Methods: An in-situ gel forming solution containing enrofloxacin was developed by physically mixing β-glycerophosphate (GP) with chitosan and poly (lactic-co-glycolic acid (PLGA). Then in-vitro release experiments were conducted using phosphate buffer pH 7.4 and sampled at discrete time intervals up to 7 days. A sensitive UV spectrophotometric method was used to analyze enrofloxacin content at 273nm.Results and Conclusion: The prepared formulation formed as a gel during 20 minutes. The release pattern for this formulation was biphasic, comprising an initial burst effect followed by an almost sustained continuous phase which released the entrapped drug for 6 days. The initial burst (~30%) in the first 24 hours can provide therapeutic concentration as a loading dose. After an initial burst release, the drug entrapped into the chitosan/GP and PLGA gel was released slowly acting as maintenance doses. Since this formulation can be injected just once for the treatment period, it seems to be economically advantageous.,