Liposomal doxorubicin and free doxorubicin in vivo quantitation method developed on CE‐LIF and its application in pharmacokinetic analysis

Abstract As a novel drug delivery system, liposomes were used to improve pharmacokinetics/pharmacodynamics (PK/PD) characters, minimize toxicity, and enhance drug–target selectivity. However, heterogeneity of drug releasing process and liposome itself challenged traditional pharmaceutical analytical techniques, especially in vivo pharmacokinetic studies. In this study, a novel liposomal doxorubicin (L‐DOX) pharmacokinetic analysis strategy was developed with capillary electrophoresis coupled with laser‐induced fluorescence (CE‐LIF) detector. The background electrolyte (BGE) system was composed of borate and sodium dodecyl sulfate (SDS), which was optimized to successfully achieve simultaneous online separation and quantitative analysis of free DOX and liposome‐encapsulated DOX. The method was applied to the in vivo pharmacokinetic study of L‐DOX in rats. The results showed that the concentration of total DOX (T‐DOX) was gradually decreasing, while the concentration of L‐DOX was relatively stable, with a concentration of 31.6 ± 4.8 µg/mL within 24 h. It was the first time to achieve liposomal drugs in vivo analysis with CE‐LIF. CE‐LIF was proved as potential rapidly real‐time analytical methods for liposomal drugs in vivo occurrence monitoring.