Preparation And In Vitro Release Study Of Rapamycin In Poly(lactic-co-glycolic )acid Microsphere For Topical Administration

Objective To effectively prevent immune rejection after composite tissue allotransplantation and reduce the dosage of sirolimus or other immunosuppressants which can cause side effects to the body, we prepare the sirolimus controlled release microspheres for local administration by an optimized method which loaded with poly(lactic-co-glycolic)acid. Apply high performence liquid chromatographic method (HPLC) to analyze the amount of sirolimus and the amount encapsulated the PLGA microparticles. Estimate the physical and chemical characteristics and determineof the particles and examine the release characteristics in vitro.Methods Using HPLC to estimated the standard substance of sirolimus and get the regression curve and equation along with intraday and interday RSD precision and recovery of sirolimus.PLGA microspheres was prepared with PLGA as carriers of sirolimus by the water-in-oil-in-water(W/ O/ W) emulsion solvent evaporation method. Using scanning electron miroscope (SEM) to exam the particle shape,size and surface morphology. The drug loading and encapsulation efficiency be estimated and in vitro release profile were determined by HPLC.Results The regression curve using to quantify sirolimus in micropaticles is A = 5.9614ρ+0.8166 r = 0.9999, SEM images of particles showed smooth surfurce morphology and the average size was calculated(121.18±27.83μm). HPLC data showed the drug loading and encapsulation efficiency were (14.39±1.32)% and (72.92±4.29)% perspectively. The cumulative in vitro release was up to 80% in 10 days. In the 20 th day the total release rate rise to 95%. From day 20 to day 23 the residue sirolimus released.Conclusions Satisfied recovery rate and low error to estimate sirolimus by HPLC indicate the accuracy and precision. Sirolimus PLGA microspheres was successfully prepared and the techonology was stable.The structure of particle is integrated and the surface is smooth. The drug loading and encapsulation efficiency in vitro release study showed the satisfied sustainable release has been achieved.