Liposomal formulation of doxorubicin has been widely applied in clinic for treatment of various cancers. The separation and measurement of free drug (drug which is not entrapped in liposomes) and liposomal drug in the plasma after injection of liposomal doxorubicin is of prime importance due to toxicity and activity concerns. In this study, a rapid and convenient method was developed to isolate and determine the non-liposomal and liposomal drugs in plasma. Plasma samples were prepared by solid phase extraction (SPE) using Oasis HLB cartridges. Liposomal doxorubicin (L-DOX) was collected in the aqueous eluate with its internal standard (IS), metformin; and non-liposomal doxorubicin (NL-DOX) and its isotope labelling IS were eluted from the cartridge by methanol containing 0.5% formic acid. After SPE separation, L-DOX and NL-DOX were subsequently quantified by a validated sensitive LC–MS/MS method individually. The calibration curves were found to be linear for L-DOX in the range of 0.156–40.0 μg/mL and for NL-DOX in the range of 3.13–200 ng/mL. The extraction recovery was about 97% for L-DOX and about 65% for NL-DOX. This method was further applied to investigate the pharmacokinetics of doxorubicin in Beagle dogs after an intravenous dose of 1.0 mg/kg Doxil^®. After injection of Doxil^®, L-DOX was the predominant component circulating in plasma, whose amount was about 1000-fold higher than that of NL-DOX. The analytical method might be helpful in pharmacokinetics and toxicity assessment of liposomal formulation.

阿霉素的脂质体制剂已在临床上广泛用于治疗各种癌症。注射脂质体阿霉素后，血浆中游离药物（未夹带脂质体的药物）和脂质体药物的分离和测量至关重要。在这项研究中，开发了一种快速方便的方法来分离和确定血浆中的非脂质体和脂质体药物。使用Oasis HLB柱通过固相萃取（SPE）制备血浆样品。脂质体阿霉素（L-DOX）以其内标（IS）二甲双胍收集在水溶液中。非脂质体阿霉素（NL-DOX）及其同位素标记IS由含有0.5％甲酸的甲醇洗脱。SPE分离后，L-DOX和NL-DOX随后分别通过经过验证的灵敏LC-MS / MS方法进行定量。发现L-DOX在0.156–40.0μg/ mL范围内和NL-DOX在3.13–200 ng / mL范围内均呈线性关系。对于L-DOX，提取回收率约为97％，对于NL-DOX，提取回收率约为65％。将该方法进一步应用于研究静脉注射剂量为1.0 mg / kg的Doxil后阿霉素在比格犬中的药代动力学^®。阿霉素的注射后^®，L-DOX是主要成分在血浆中循环，其量为约1000倍比NL-DOX的更高。该分析方法可能有助于脂质体制剂的药代动力学和毒性评估。