盐酸米托蒽醌热敏脂质体的制备及评价

Preparation and evaluation of mitoxantrone hydrochloride thermosensitive liposomes

目的制备盐酸米托蒽醌长循环热敏脂质体(M-LTL),建立其含量及包封率测定方法,并对其体内外热敏性进行研究。方法薄膜分散及pH梯度法制备M-LTL,高效液相色谱法(HPLC)测定脂质体中盐酸米托蒽醌(MIT)的含量,微柱离心法测定包封率。测定不同温度下M-LTL的释药率。以荷H22肝癌小鼠为肿瘤模型,肿瘤生长曲线和抑瘤率为指标,评价M-LTL的抑瘤效果。结果:M-LTL粒径均一,平均粒径为92 nm,平均包封率为99.8%。辅料和溶剂不干扰主药含量测定,线性范围2～20.0μg/ml。体外释药表明,药物在37℃与42℃下30 min内释药率分别为5.7%和63.7%。体内实验中M-LTL加热组和M-LTL不加热组抑瘤率分别为81.5%和61.1%。结论所制备的M-LTL粒径均一,包封率高。含量及包封率测定方法简便快捷,准确可靠。M-LTL加热时能够快速释药,具有热敏性,与热疗相结合能够有效抑制肿瘤生长。

Objective To prepare mitoxantrone-loaded long-circulated thermosensitive liposomes（M-LTL）,establish the determination methods for the content and entrapment efficiency determination and study the thermosensitive characteristics in vitro and in vivo.Methods M-LTL were prepared by the thin film hydration method combined with pH gradient method.HPLC methods were established to determine the drug content.Liposomes and free drug were separated through Dextran G-50.Tumor-bearing mouse model was established by subcutaneous graft of H22 cancer cell.M-LTL heating-free group and mitoxantrone hydrochloride（MIT） injection group were taken as control groups,and the normal saline group as blank group.The tumor growth curve was obtained and the tumor inhibitory rate was calculated.Results M-LTL appeared uniform and mean particle size was 92nm.The average entrapment efficiency was 99.8%.The excipients and solvents did not interfere with the assay.A good linear relationship was found between peak area and the concentration of M-LTL in the range of 2-20.0 μg / ml（r = 0.9998）.The in vitro release test of M-LTL demonstrated that the drug release amount was not more than 5% at 37℃ in 15 min,while about 60% of the total drug released at 42℃ in 5 min.The in vivo test demonstrated that the tumor inhibitory rate of M-LTL heating group had significant difference（P 0.05） compared with M-LTL heating-free group,injection（M-I） and normal saline groups,with tumor inhibitory rates at 81.5%,61.1% and 40.1%,respectively.Conclusion High entrapment efficiency could be attached when pH gradient method was used for M-LTL preparation.The method is simple,accurate and reliable for the determination of the content and entrapment efficiency.M-LTL has an obvious thermosensitive characteristic both in vitro and in vivo.