Floor B J, Klein A E, Muhammad N, Ross D
J Pharm Sci. 1985 Feb;74(2):197-200. doi: 10.1002/jps.2600740219.
Simple and specific assays for etoposide, related impurities, and benzyl alcohol, as well as its degradation product, benzaldehyde, in injectable formulations were developed using high-performance liquid chromatography (HPLC). Etoposide, benzyl alcohol, benzaldehyde, and four etoposide impurities were determined with a mobile phase containing 26% acetonitrile in pH 4.0 acetate buffer with methyl p-aminobenzoate as the internal standard. Two etoposide precursors were additionally determined using 60% acetonitrile in the mobile phase with biphenyl as the internal standard. The assays were run sequentially. The etoposide assay had a total variability of less than 1% (RSD) and a recovery from placebo of 99.4%. Mean recovery of impurity standards spiked at the 2% level relative to the etoposide level was 98%. Recoveries for benzyl alcohol and benzaldehyde were 100.5% and 102.2%, respectively. Absorbance ratios generated from samples and compared with undegraded standards demonstrated specificity for etoposide. Similar response regression equations with correlation coefficients greater than 0.99 were obtained for etoposide and four impurities over the 2-8 micrograms/mL concentration range, indicating that an etoposide standard could be used to quantitate low impurity levels down to 0.2% relative to the etoposide injectable concentration. Benzaldehyde could be reliably detected at concentrations down to 0.5 micrograms/mL, equivalent to 0.16% of the benzyl alcohol level.
采用高效液相色谱法（HPLC）开发了用于测定注射剂中依托泊苷、相关杂质、苯甲醇及其降解产物苯甲醛的简单且特异的分析方法。依托泊苷、苯甲醇、苯甲醛和四种依托泊苷杂质采用含26%乙腈的pH 4.0醋酸盐缓冲液作为流动相，对氨基苯甲酸甲酯作为内标进行测定。另外两种依托泊苷前体采用流动相中含60%乙腈，联苯作为内标进行测定。这些分析依次进行。依托泊苷分析的总变异小于1%（相对标准偏差），从安慰剂中的回收率为99.4%。相对于依托泊苷水平在2%水平加标的杂质标准品的平均回收率为98%。苯甲醇和苯甲醛的回收率分别为100.5%和102.2%。样品产生的吸光度比值与未降解标准品相比显示了依托泊苷的特异性。在2 - 8微克/毫升浓度范围内，依托泊苷和四种杂质获得了相关系数大于0.99的相似响应回归方程，表明依托泊苷标准品可用于定量低至相对于依托泊苷注射剂浓度0.2%的杂质水平。苯甲醛在低至0.5微克/毫升的浓度下可可靠检测，相当于苯甲醇水平的0.16%。
