不同分子量葡聚糖-地塞米松连接物的体外靶向释药特性不同分子量葡聚糖-地塞米松连接物的体外靶向释药特性

目的筛选具有结肠靶向性的葡聚糖-地塞米松连接物,探讨葡聚糖分子量对连接物体外释药特性的影响。方法将不同分子质量葡聚糖-地塞米松连接物与大鼠胃肠道不同部位内容物稀释液一起孵育,采用反相高效液相色谱法检测地塞米松及地塞米松琥珀酸单酯的释放情况。结果在160 min孵育过程中,胃内容物中未检测到释放的地塞米松及地塞米松琥珀酸单酯;DexD26和DexD50在结肠及盲肠内容物中释放出地塞米松(包括地塞米松琥珀酸单酯)的总量分别是其在小肠近端及小肠远端内容物中释放总量的4.0和3.6倍;DexD2和DexD7.6在结肠及盲肠内容物中释放出地塞米松(包括地塞米松琥珀酸单酯)的总量分别是其在小肠近端及小肠远端内容物中释放总量 的2.0和1.9倍。结论葡聚糖分子质量对连接物的体外释药特性有明显影响,大分子质量葡聚糖-地塞米松连接物具有较大的结肠定位释放潜力。

Characteristics of drug-release in vitro of different dextran-dexamethasone conjugates

AIM: To evaluate the effects of molecular weight of dextran on drug-release of conjugate in vitro by screening colon-specific conjugates. METHODS: The conjugates, synthesized with different molecular-weight dextran and dexamethasone, were incubated in the contents of different parts of rat gastrointestinal tract at 37 degrees C. The release of dexamethasone(Dex) and dexamethasonehemisuccinate was determined by HPLC. The mobile phase consisted of 35% acetonitrile and 65% trisodium citrate (50 mmol.L-1, adjusted to pH 4.1 with phosphoric acid). RESULTS: There was no release of dexamethasone or dexamethasonehemisuccinate from conjugates in the stomach contents. The amount of Dex (including dexamethasonehemisuccinate) released from DexD26 in the contents of colon and cecum was shown to be 4.0 times higher than that released in the contents of proximal and distal small intestine while the amount of Dex (including dexamethasonehemisuccinate) released from DexD50 was shown to be 3.6 times higher. The amount of Dex (including dexamethasonehemisuccinate) released from DexD2 in the contents of colon and cecum and from DexD7.6 were 2.0 times and 1.9 times higher, respectively, than that released in contents of proximal and distal small intestine. CONCLUSION: The molecular weight of dextran showed marked effect on drug-release of the conjugate in vitro, and the conjugates with larger molecular-weight dextran have great potential in colon-specific delivery of dexamethasone.