Preparation Of Microemulsion And Vesicle And The Study Of Their Application In Insulin Medicine

Microemulsion and spontaneous xesicle system which were used as insulin(INS) drug delivery system were prepared. The two W/O microemusion of Tween80-Span80/ethanol/Butyl butyrate/H2O(Ⅰ) and Tween80-Span80/ n-Butylalcohol/ethyl-oleate/H2O(Ⅱ)to envelop INS were studied. By choosing the maximum solved water (solution) as the goal, the compositions of microemulsion to envelop INS were chosen. The conductance method was used to divide O/W, W/O and B.C. regions of (Ⅰ)and(Ⅱ). The Dynamic Light Scattering (DLS) to evaluate the particle diameters and the polydispersity of (Ⅰ)and(Ⅱ), the influences of temperature, salinity as well as the pH on(Ⅰ)and(Ⅱ) microemulsion areas were also considered. Viscosity measurements were performed using a model viscosimeter and fluorescence scanning was used to determine the molecular localization and state of insulin in the microemulsion. Based on the study of our group, spontaneous vesicle systems in aqueous solution of mixture of cationic surfactants dicetyl dimethyl ammonium chloride (DCDAC) and tri-(dodecyl-dimethyl dydroxy-propyl ammonium chloride) phosphate (PTA) with sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS) were studied respectively, and the influences of temperature, salinity as well as the pH on different vesicle systems were studied. The entrapment efficiency of INS in microemulsion and spontaneous vesicle systems were measured with the 125I Isotope tracing method and dialysis bag-Ultraviolet Spectrophotometer respectively.Results shows that W/O microemulsion forms when water content below 41% in the(Ⅰ),while below 50% in the(Ⅱ). The two microemulsion region changed slightly with the change of temperature, salinity and the pH. DLS also showed that the (Ⅰ)had its particle diameter between 35～45nm with polydispersity between 0.29～0.37, and that the particle diameter kept almost unchanged with the decrease of pH but decreased a little with the addition of INS. The diameter of the INS loaded W/O microemulsion prepared after 3 days decreases suddenly but kept with 37nm within a month. The diameter of the INS loaded W/O microemulsion prepared after 5 days increased suddenly but kept with 68.6nm within a month. However, the viscosity measurements along certainly selected dilution lines to the microemulsion indicate that no phase invert occurred when water content below 50% in the(Ⅱ). There was no insulin emission spectrum in the INS -microemulsion fluorescence spectrum. in the(Ⅱ) Spontaneous vesicles were formed in certain molar proportion and total surfactant concentration. we choose the proper system of PTA/SDS=3/7,PTA/SDS=2/8 and DACDAC/SDBS=1/9 which keep stable within different temperature, salinity and the pH to envelop INS. The entrapment efficiencies were 29.57%,18.87% and 19.49% with the total concentration 5.0×10-3mol/L,5.0×10-3mol/L and 8.0×10-4mol/L respectively. The INS loaded(Ⅰ)W/O microemulsion accessed to the sustained release stage at 7.5h and gave its release rate to 66.20% at 40h,and the INS loaded(Ⅱ)W/O microemulsion gave its release rate to 24.69% at 50h. The INS loaded W/O microemulsion possessed eminent sustaining release efficiency and the assay of cytostatic and cytotoxic indicated that the microemulsion can be used as drug delivery at low concentration.