Liposomes with high encapsulation capacity for paclitaxel: Preparation, characterisation and in vivo anticancer effect.

Paclitaxel (PTX) is approved for the treatment of ovarian and breast cancer. The commercially available preparation of PTX, Cremophor EL(R) is associated with hypersensitivity reactions in spite of a suitable premedication. In general, the developed liposomal PTX formulations are troubled with low PTX encapsulation capacity (maximal content, 3 mol%) and accompanied by PTX crystallisation. The application of "pocket-forming" lipids significantly increased the encapsulation capacity of PTX in the liposomes up to 10 mol%. Stable lyophilised preparation of PTX (7 mol%) encapsulated in the liposomes composed of SOPC/POPG/MOPC (molar ratio, 60:20:20) doped with 5 mol% vitamin E had the size distribution of 180-190 nm (PDI, 0.1) with zeta-potential of -31 mV. Sucrose was found to be a suitable cryoprotectant at the lipid:sugar molar ratios of 1:5-1:10. This liposomal formulation did not show any evidence of toxicity in C57BL/6 mice treated with the highest doses of PTX (100 mg/kg administered as a single dose and 150 mg/kg as a cumulative dose applied in three equivalent doses in 48-h intervals). A dose-dependent anticancer effect was found in both hollow fibre implants and syngenic B16F10 melanoma mouse tumour models.