Preparation And Evaluation Of Anemoside B4 Rectal In Situ Gel For Treatment Of Ulcerative Colitis

Objective: Ulcerative colitis(UC)is mainly based on enemas and suppositories,which leads to low bioavailability and poor patient compliance.In this paper,combined with the physical and chemical properties of Anemoside B4 and the appropriate route of administration,it was prepared into an in situ gel for transrectal administration,and appropriate absorption enhancers were added to the prescription to construct a new drug delivery system suitable for Anemoside B4,and to elucidate its in vitro and in vivo release characteristics.This has important guiding significance for new dosage forms and new technologies in the transrectal administration of active ingredients of traditional Chinese medicine.It also has a good role in promoting the level of Chinese medicine preparations.Methods:1.The Caco-2 cell model and isolated porcine rectal mucosa were used to screen the type and concentration of the best absorption enhancer,and the dosage was further determined by CCK-8 method.2.Poloxamer 407(P407),poloxamer 188(P188)and hydroxypropyl methyl cellulose(HPMC)were selected as the matrix of in situ gel,and the gelation temperature was used as the index.The ratio of each component in the prescription was optimized by single factor combined with Box-Behnken response surface method to determine the optimal prescription and preparation process of the preparation.3.The prepared Anemoside B4 in situ gel was characterized,and the appearance,p H,gelation temperature,gelation time,viscosity,gelation strength,rheology properties,stability and in vitro release of Anemoside B4 in situ gel were investigated.4.The prepared Anemoside B4 in situ gel was evaluated in vivo.Firstly,the rectal mucosa of SD rats was sectioned for 7 consecutive days to investigate the irritation of Anemoside B4 in situ gel on rectal mucosa;Secondly,the retention time of in situ gel in the rectum of SD rats was measured by methylene blue method;Finally,pharmacokinetic studies were conducted on SD rats to determine the pharmacokinetic parameters of the drug in plasma.5.The pharmacodynamics of SPF male C57BL/6 mice was studied to investigate the improvement of the lesion state of UC mice by adding absorption enhancers.Results:1.The results showed that different absorption promoters were added.For example,sodium caprate(SC),water soluble azone(azone),Tween-80,sodium0cholate(CAS),arginine(Arg),and hydroxypropyl-β-cyclodextrin(HP-β-CD)can promote their absorption to varying degrees.Among them,HP-β-CD has the best absorption effect,followed by SC and Tween-80.According to the safety results,HP-β-CD and SC were selected as two absorption enhancers.When the concentration was 2.5% and 1%,the absorption effect was the best.Therefore,2.5% HP-β-CD and1% SC were selected as two absorption enhancers for the prescription of Anemoside B4 rectal in situ gel.2.The results showed that the optimal formulation conditions of the blank prescription were P407 17.41%,P188 4.07%,HPMC 0.44%.According to the experimental results of the first chapter,the final formulations of the two in situ gels were 2.5 % HP-β-CD,P407 17.41%,P188 4.07%,HPMC 0.44% and 1 %SC,P40717.41%,P188 4.07%,HPMC 0.44%,and the solvent was water.3.The two formulations of Anemoside B4 in situ gel were uniform clear transparent gel,which changed from liquid phase to gel state at rectal physiological temperature.The gelation temperature was(32.83 ± 0.06)°C and(35.93 ± 0.15)°C,the gelation time was(28.00 ± 4.00)s and(63.33 ± 5.51)s,the p H was 6.77 ± 0.04 and 8.67 ± 0.04,the viscosity was 4500 m Pa·s,and the gel strength was(50 ± 5)g.The rheological evaluation showed that the in situ gel of Anemoside B4 showed stable non-Newtonian mechanical pseudoplastic fluid characteristics at 25 and 36 °C.The content of Anemoside B4 in the in situ gel of Anemoside B4 was determined by HPLC.In vitro release test showed that the cumulative permeability within 6h was80 %,and the fitting equations were in accordance with the first-order kinetic equation.The preliminary stability test results showed that it was unstable at high temperature,indicating that the preparation should avoid high temperature preservation and meet the requirements of rectal preparation.The resistance reversibility of Caco-2 cell model was used to study the absorption mechanism of HP-β-CD and SC.The results showed that HP-β-CD and SC could promote the absorption of drugs by opening the tight junction between cells..4.The results showed that each prescription had no irritation to the rectal mucosa,with an average retention time of more than 6 hours,and the absolute bioavailability of HP-β-CD and SC absorption enhancers in situ gel formulation was 72.05% and60.34%,respectively,and the absolute bioavailability without absorption enhancers was 38.45%,indicating that the absolute bioavailability of Anemoside B4 in situ gel was improved to varying degrees by adding appropriate absorption enhancers to the formulation.5.The results showed that each prescription of Anemoside B4 in situ gel could significantly improve the clinical symptoms of UC mice,such as weight loss,shortening of colon length,splenomegaly,etc.Among them,the therapeutic effect of adding absorption enhancers to the in situ gel prescription was relatively good.Conclusion:In this paper,Anemoside B4 was taken as the research object,combined with its physical and chemical properties and the route of administration,it was made into rectal in situ gel with absorption enhancers,and its in vivo and in vitro evaluation was carried out,which proved that rectal in situ gel with absorption enhancers could improve the bioavailability of Anemoside B4,and had a certain inhibitory effect on the symptoms of UC mice,fully reflecting the advantages of rectal in situ gel preparations,To lay the foundation for further research on clinical treatment of UC preparations.