Strategy to provide a useful solution to effective delivery of dihydroartemisinin: development, characterization and in vitro studies of liposomal formulations

Dihydroartemisinin is one of the most potent anticancer artemisinin-like compounds and induces cancer cell death by apoptotic pathways. Besides its effectiveness, it is a poorly water soluble drug with low bioavailability and low half-life (34-90 min), therefore, the development of new formulations of dihydroartemisinin that enable quick availability to the body is in great need. Conventional (P90G and cholesterol) and stealth liposomes (P90G; cholesterol and PE 18:0/18:0 PEG 2000) for dihydroartemisinin delivering to cancer cells were developed for the first time. Liposomes were prepared according to the film hydration method; both formulations show physical characteristics as drug carrier for parental administration and good values of encapsulation efficiency (71% conventional liposomes and 69% stealth liposomes). Physical and chemical stabilities were evaluated under storage condition and in presence of albumin. Cellular uptake efficiency of liposomes was determined by flow cytometry. Higher internalization occurred in the conventional formulation than in the stealth one suggesting that hydrophilic steric barrier of PEG molecules can reduce cellular uptake. Flow cytometry analysis was used also like alternative technique for rapid size determination of liposomes. Cytotoxicity studies in the cell line MCF-7 confirmed absence of toxicity in blank formulations and suggested that liposomes may be a suitable carrier for delivery of DHA avoiding the use of organic solvents. Cytotoxicity of DHA and its relative liposomal formulations was evaluated during a time course experiment in the same cell line and results confirmed the modified release from vesicles after cellular uptake.