A liposomal formulation of doxorubicin, composed of hexadecylphosphocholine (HePC): physicochemical characterization and cytotoxic activity against human cancer cell lines

Abstract

The overall goal of this study was to prepare a novel liposomal formulation of doxorubicin, composed of hexadecylphosphocholine (HePC), as a combined formulation and to study its activity against cancer cells and peripheral blood mononuclear cells (PBMCs), in terms of efficacy and toxicity. Liposomes composed of HePC/egg phosphatidylcholine/stearylamine (HePC/EPC/SA) 10:10:0.1 (molar ratio) (1) and EPC/SA 10:0.1 (molar ratio) (2) were prepared and doxorubicin was encapsulated using the pH gradient method. Determination of lipids and doxorubicin has been achieved by high-performance thin-layer chromatography coupled with a flame-ionization detector. Prepared liposomes were characterized for their size distribution and their zeta-potential at each step of the preparation procedure. In vitro release studies have been evaluated in buffer and culture medium at 25 and 37 degrees C for 24 hours period. Liposomal formulations, free doxorubicin and HePC were tested against cancer cell lines and PBMCs, using sulforhodamine B (SRB) assay. Doxorubicin was encapsulated into the liposomes 1 and 2 at a drug to lipid molar ratio of 1.08 and 0.77, respectively, with an entrapping efficiency almost 100% in both cases. Doxorubicin was retained into liposome 1 up to 70% at 25 degrees C in TES, while up to 80% was released from 1 when liposomes were incubated at 37 degrees C either in culture medium or in the TES buffer at 24 hours. The activity of doxorubicin was retained or slightly improved when entrapped into liposomes 1 and 2, while liposomal formulation 1 encapsulating doxorubicin was found to be less toxic against normal cells (PBMCs). The combination of HePC and doxorubicin in one combined formulations justified as an improvement of the therapeutic index (TI) of doxorubicin in terms of efficacy and toxicity.