胰岛素W/O型微乳液的制备及体外释药性能

制备了包封胰岛素(INS)的Tween 80-Span 80/乙醇/丁酸乙酯/水体系的W/O型微乳液。以最大增溶水量为指标,选择了合适的微乳液组分包封INS。考察了温度、盐度和pH对微乳液区域的影响。电导率法区分了微乳液的O/W、W/O和B.C.区域。动态光散射测定了微乳液的粒径和多分散度。125I同位素示踪法测定了INS微乳液体外释放效果。结果表明,微乳体系在水/乙醇(质量比为1.8∶1)的质量分数小于41%时形成W/O型微乳液,温度、盐度升高和pH降低使微乳区稍有减小。微乳液粒径和多分散度分别为35~45 nm和0.29~0.37。pH的降低对微乳液粒径影响不大,而药物的加入使微乳液粒径略有减小。载药微乳液粒径在制备3 d后突降,以后的27 d内保持在37 nm左右。该载药微乳液在7.5 h后进入缓释阶段,40 h时INS的释放率为66.20%。

Preparation and in vitro Release Test of Insulin Loaded W/O Microemulsion

The W/O microemulsion of Tween 80-Span 80/ethanol/butyl butyrate/H_2O to envelop insulin(INS) was prepared.By choosing the maximum solved water(solution) as the goal,the constituents of microemulsion to envelop INS were investigated,and the influences of temperature,salinity as well as the pH on microemulsion areas were also considered.To test some properties of the microemulsion,the conductance method was used to divide O/W,W/O and B.C.regions,the dynamic light scattering(DLS) to evaluate the particle diameters and polydispersity of the microemulsion,and the ~(125)I isotope tracing method to measure the release rate of INS loaded in W/O microemulsion.Results show that W/O microemulsion forms when water and ethanol(m(H_2O)∶m(ethanol)=1.8∶1) content is below 41% in the microemulsion system.The microemulsion region decreases slightly with the increase of temperature and salinity and the decrease of pH.DLS shows that the microemulsion has particle diameter between 35～45 nm with polydispersity between 0.29～0.37,and the particle diameter keeps almost unchanged with the decrease of pH but decreases a little with the addition of INS.The diameter of the prepared INS loaded W/O microemulsion decreases suddenly after 3 days but keeps to 37nm within a month.The INS loaded W/O microemulsion accesses the sustained release stage at 7.5 h and gives its release rate to 66.20% at 40 h.