羟基喜树碱脂质体的制备及其包封率测定

Preparation of hydroxycamptothecin liposomes and its encapsulation rate determination

目的：制备符合肺靶向要求的羟基喜树碱脂质体并测定其包封率。方法：采用薄膜分散一冻融法制备羟基喜树碱脂质体；用凝胶柱色谱法分离游离药物；高效液相色谱法测定包封率。采用ZORBAXSB-C18柱（4．6mm×250mm，5μm），以75mmol·L^-1醋酸铵-5mmol·L^-1三乙胺（冰醋酸调pH至5．6）缓冲液／乙腈（75：25）为流动相，流速1mL·min^-1，检测波长383nm，柱温30℃。结果：制得的脂质体平均粒径大于2μm，包封率大于70％。在选定的色谱条件下，羟基喜树碱与辅料能完全分离，在0．2～20mg·L^-1范围内，药物浓度与峰面积呈良好的线形关系（r=0．9998）。结论：薄膜分散-冻融法适用于制备肺靶向羟基喜树碱脂质体；凝胶柱-高效液相色谱法操作简单，准确，重复性好，可用于测定羟基喜树碱脂质体的含量和包封率。

OBJECTIVE To prepare lung targeting hydroxycamptothecin liposomes and to establish HPLC method for determination of hydroxycamptothecin and its encapsulation rate. METHODS The hydroxycamptothecin liposomes were prepared by thin film method with freeze-thawing steps, Unloaded hydroxycamptothecin was separated by Sephadex-G50 chromatogra- phy. HPLC method was used to determine the encapsulation rate of hydroxycamptothecin liposomes. The chromatographic procedure was carried out on a ZORBAX SB-C48 column（4. 6 mm×250mm,5μm） ,using the mixture of 0. 075 mol·L^-1 ammonium acetate-0. 005 mol·L^-1 triethylamine buffer solution （pH 5.6）/acetonitrile （75：25） as mobile phase with a flow rate of 1 mL·L^-1 and UV detection wavelength set at 383 nm. The column temperature was maintained at 30 ℃. RESULTS The encapsulation rate of hydroxyeamptothecin liposomes was more than 70%, The average size was more than 2 μm Hydroxycamptothecin had a good linear relation within the range of 0. 2 - 20 mg·L^-1 with the correlation coefficient of 0. 999 8. CONCLUSION Thin film method with freeze-thawing steps could be used to prepare lung-targeting hydroxycamptothecin liposomes. The Sephadex G50-chromatography-HPLC method was convenient, accurate and suitable for determination of hydroxycamptothecin and the encapsulation rate of hydroxycamptothecin liposomes.