Relaxation of paclitaxel/lipid monolayers at the air-water interface

Paclitaxel (Taxol((R))) is a novel antineoplastic drug of high potency against various cancers, especially ovarian and breast cancer. However, due to its poor water solubility, excipients such as Cremophor EL are needed for its clinical administration, which cause additional side effects. Liposomes (lipid bilayer vesicles) could be a better alternative system of promise. In this paper, the lipid monolayer at the air/water interface was used as a model membrane to characterize the molecular interactions between paclitaxel and lipids. The relaxation kinetics of pacitaxel/dipalmitoylphosphatidylcholine (DPPC) monolayers was investigated by measuring the surface area as a function of time at a constant surface pressure of 20mN/m. The data were then fitted to a theoretical model. The results showed that the relaxation process might be explained by the surfactant nucleation and growth mechanism.