The glass transition temperature (Tg) of liposomal suspensions, in which glucose, sucrose, mannitol and trehalose are used as cryoprotectants respectively, are measured by differential scanning calorimetry (DSC), the protective effect of the cryoprotectants added for liposomes during freeze - drying is investigated. The results show that the Tg of liposomal suspension with trehalose is the highest, while that with glucose is the lowest. Depending on the concentration, the vesicle size of liposomes with trehalose as cryoprotectant varies less,while the vesicle size of liposomes, with glucose as cryoprotectant varies bigger during the process of freeze - drying. The pharmaceuticals of water - soluble ftorafur and lipid - soluble vitamin A encapsulated in liposomes are freeze - dried. The retention rates of the encapsulated pharmaceuticals inside the liposomes are measured with a high performance liquid chromatography. The results indicate that the retention rate for liposomes with trehalose is the highest, and the leakage of the pharmaceuticals is less than that with glucose being cryoprotectant. Through a series of study, trehalose is identified as a better cryoprotectant and an optimized freeze- drying procedure for liposomes is obtained.%利用差示扫描量热仪(DSC)测量了以葡萄糖、蔗糖、甘露醇、海藻糖作为保护剂的脂质体悬浮液的玻璃化转变温度Tg,研究了冷冻干燥工艺对脂质体质量的影响,并讨论了上述保护剂对脂质体在冷冻干燥过程中的保护效果,结果表明:以海藻糖作为保护剂的脂质体的玻璃化转变温度Tg最高为-30.4℃,而以葡萄糖作为保护剂的Tg最低为-39℃;在冻结和冷冻干燥过程中,以海藻糖作为保护剂的脂质体的粒径变化最小,以葡萄糖为保护剂的脂质体粒径变化最大.还对脂质体包封水溶性药物喃氟啶和脂溶性药物维生素A进行了冻干研究,并利用WATERS高效液相色谱仪测量了冻干后脂质体对药物的包封率.结果显示:以海藻糖为保护剂的脂质体对药品的包封率较高,泄露少,而以葡萄糖为保护剂的脂质体对药品的包封率较低,泄露多.通过研究得出海藻糖是一种较好的保护剂,并优化了脂质体冷冻干燥工艺.
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