Study On Eye Drops Of Lutein Liposomal Microgels

Lutein,also known as “phytoprogesterone”,is a carotenoid without vitamin A activity,which contains two different ionone rings.And it is mainly distributed in the retina,macular area,and lens in the human eyes.Filter blue light,protect the retina,maintain vision and other important functions.Lutein preparations can treat eye diseases such as myopia,age-related macular degeneration,cataracts,and retinopathy,and have a wide range of effects on eye diseases caused by lack of lutein.However,lutein is insoluble in water and easily soluble in solvents such as chloroform and ethyl acetate;its structure is easily damaged under conditions of light,heat,acid,humidity,etc.,which limits the application of lutein in pharmacy.Liposomes have strong embedding ability to lutein,which can protect lutein from being oxidized by outside oxygen and light,and effectively inhibit the instability of lutein.Short residence time,poor patient compliance,and low bioavailability are the main problems faced by eye drops.The microgel has the characteristics of small particle size,high drug loading,sensitive environmental response and good biocompatibility,and can achieve good sustained and controlled release effects.Microgel eye drops are temperature sensitive and exist as a liquid at room temperature,and form semi-solid in the eye after administration.Microgel eye drops can increase the retention time of the eye and reduce the drug spillage loss,thus improving the drug bioavailability and reducing adverse reactions.This subject is based on previous research,loading lutein liposomes into the microgel to prolong the action time of lutein in the eye and achieve a slow-release effect,thereby improving its bioavailability.Through pre-experiment and single factor screening,the type and amount of solvent used to synthesize PNIPAM-COOH,the amount of n-hexane;the type and dose of solvent used to synthesize AHA,the dose of ADH;the AHA and PNIPAM-COOH feeds used to synthesize HA-g-PNIPAM microgel Ratio,solution dosage,EDC dosage and lutein liposome dosage(using gelation temperature,viscosity and particle size as indicators).According to the results of single factor experiments,several factors that have a great influence on the quality of lutein liposome microgels were selected,The results are:(?)Process:Synthesis of PNIPAm-COOH: In a three-necked flask,1 g of recrystallized monomer NIPAAm and 0.02 g of azobisisobutyronitrile were dissolved in 25 m L of methanol,and 50μL of 3-hydroxypropionic acid was added after dissolution.The temperature was increased to 60 C.under nitrogen protection,and the nitrogen gas was continuously stirred and stirred.After 24 hours,the reaction was completed.The solvent was evaporated off.The crude product was dissolved in acetone after vacuum drying,and then precipitated with cold n-hexane.The precipitate was carefully washed three times with cold n-hexane to remove unreacted products,and then dried in vacuo to give a slightly yellow powder.Synthesis of AHA: HA(0.1 g)and hydrazide cross-linking agent(ADH,10 g)dissolved in water were reacted with 0.2 g of EDC at p H 4.75 for 24 hours.It was adjusted and maintained by adding a 0.1 M hydrochloric acid solution to the reaction mixture.p H.After the reaction was completed,0.1 M sodium hydroxide was added to adjust the p H of the reaction mixture to 7.The resulting solution was dialyzed against 0.1M Na Cl(with a molecular weight cut-off of 3500 Da)and dialyzed against distilled water for 24 hours.The polymer solution was filtered through a 0.22μm microporous filter membrane,freeze-dried,and stored at 4 ° C for later use.Synthesis of HA-g-PNIPAm microgel: Dissolve 0.1 g of AHA and 0.2 g of PNIPAAm-COOH in 100 m L of distilled water,add 0.25 g of EDC and incubate at 4 ℃ for 48 hours.The p H of the reaction mixture was then adjusted to 6.0 and incubated at room temperature for 24 hours.The reaction solution was charged into a dialysis bag washed in advance(with a molecular weight cut-off of 7000 Da),and dialyzed with deionized water for 3 days.After prefreezing,it was lyophilized for 36 hours to obtain HA-g-PNIPAAm polymer,which was stored at 4 ℃for later use.Synthesis of HA-g-PNIPAm microgel: Dissolve 0.1 g of AHA and 0.2 g of PNIPAAm-COOH in 100 m L of distilled water,add 0.25 g of EDC and incubate at 4 ℃ for 48 hours.The p H of the reaction mixture was then adjusted to 6.0 and at room temperature for 24 hours.The reaction solution was charged into a dialysis bag washed in advance(with a molecular weight cut-off of 7000 Da),and dialyzed with deionized water for 3 days.After prefreezing,it was lyophilized for 36 hours to obtain HA-g-PNIPAAm polymer,which was stored at 4 ℃ for later use.In this paper,the membrane(dialysis bag)and membrane-free methods were used to investigate the drug release and erosion kinetics of lutein liposome microgels.The results show that lutein liposome microgels have a sustained release effect.Its dissolution and drug release accord with zero-order kinetic characteristics,and drug release is mainly controlled by dissolution.The stability of xanthophyll liposome microgels was tested in accordance with the guidelines for stability studies in the 2015 edition of the Chinese Pharmacopoeia.According to the influencing factor test and accelerated test,it is concluded that at high temperature(40℃)and room temperature(25℃),the content of lutein decreases significantly,and the physical properties of the microgel change within a reasonable range.Conclusion: The physical and chemical properties of lutein liposome microgels are relatively stable at low temperature(6℃±2℃).Draize eye irritation test method was used to investigate the irritation of lutein liposome microgels.According to the experimental results,it was concluded has no irritation to eyes,and preliminary laboratory studies have shown its safety High,suitable for eye administration.