Preparation And In Vivo Evaluation Of Ion-sensitive Azithromycin Ophthalmic In Situ Gel

Objective: In this study,azithromycin was chosen as a model drug,and the ionic sensitive azithromycin in-situ gel preparation was prepared by using deacetylated gellan gum and xanthan gum as gel matrix.The methodology for the determination of content,related substances and dissolution of azithromycin ophthalmic gel was established.The drug release curve in vitro,the irritation of the preparation in the eye and the stability of the preparation were investigated,and the analytical methods of azithromycin in-situ gel preparation was established.Methods: HPLC and UV spectrophotometry were used to establish in vitro quality analysis of ion-sensitive azithromycin eye gel.The deacetylated gellan gum solution was prepared by water bath method,and the types of deacetylated gellan gum and the preparation conditions of gel were screened.According to the viscosity of the sample,the concentrations of deacetylated gellan gum and xanthan gum were screened preliminarily.The central composite design-response surface methodology was used to optimize the formulations according to the changes of the viscosity of the formulation at room temperature and after mixing with tear solution.According to the optimization results,the leading formulation was prepared,and the amount of excipients such as cosolvent,osmotic pressure regulator,preservative,pH regulator and the sterilization method was analyzed.Dialysis bag method and modified paddle method were used to investigate the drug release curve in vitro,and fit the drug release model.The physical and chemical properties of ionic sensitive azithromycin in-situ gel preparation,such as properties,visible foreign bodies,asepsis,pH,content,total impurity,viscosity of the preparation,viscosity after forming gel were investigated.In view of the rheological characteristics of the preparation,the effects of temperature and viscometer speed(shear speed)on the viscosity were investigated.According to the Draize eye irritation test,the irritation of the preparation sample to the eyes of rabbits was investigated through single and multiple drug administration tests using self-control method.In addition,the stability of the preparation was preliminarily investigated under the conditions of centrifugation,high temperature,low temperature and strong light.Results: Through a series of methodological validation of the in vitro analysis method,the results showed that the methods could accurately determine the content,impurities and in vitro release of homemade azithromycin ophthalmic gel preparations.The results of degradation experiments showed that azithromycin was sensitive in high-temperature,acidic and oxidation conditions.By sulfuric acid treatment,the maximum absorption wavelength of the sample was at 482 nm,thus avoiding the end absorption of azithromycin at 210 nm wavelength.In the experiment,the deacetylated gellan gum produced by CPKelco company was used to prepare gel matrix by 90? water bath method.Through the results of viscosity and dropability,determined the optimum concentration of deacetylated cementitious gum and xanthan gum was 0.4%-0.6% and 0.1%-0.3% respectively.Then,the central composite design response surface test was further chosen 0.48(w/v)deacetylated gellan gum and 0.10%(w/v)xanthan gum as the optimal gel matrix.A little dilute hydrochloric acid solution as the assistant solvent of azithromycin,2.5%(w/v)mannitol as osmotic pressure regulator,0.005% benzalkonium chloride as preservative,and 0.2% tri(hydroxymethyl)aminomethane solution was used to adjust the pH of the preparation to 6.50.Compared with the dialysis bag method,the improved paddle method could better simulate the physiological environment of the eyes.The results of model fitting showed that the drug release conformed to the first-order kinetic model.The single and multiple eye irritation tests showed that the preparation has nonirritation to rabbit eyes.The formulation was stable under centrifugal,low temperature and light conditions,and unstable at high temperature conditions.Conclusion: All the experimental results suggested that ion-sensitive azithromycin ophthalmic gel could improve the retention time,enhance the bioavailability of drugs and reduce the frequency of administration.In addition,the preparation has good stability and nonirritation.Therefore,ion-sensitive delivery system will have bright application prospects.