Liposomal formulation for co-delivery of paclitaxel and lapatinib, preparation, characterization and optimization.

Paclitaxel (PTX) is one of the most promising natural anticancer agents with a wide therapeutic range which is limited by its hydrophobic nature, low therapeutic index and more importantly, the emergence of multidrug resistance (MDR). Lapatinib (LPT) is a dual tyrosine kinase inhibitor with a significant potential to inhibit p-glycoproteins which form one of the main groups of proteins responsible for efflux pump mediated MDR. To overcome the PTX related MDR, a novel liposomal formulation was optimized for co-delivery of PTX and LPT by applying the D-optimal response surface methodology. The encapsulation efficiency (EE%) of the optimized formulation for LPT and PTX was 52 ± 3% and 68 ± 5, respectively. The optimized formulation showed a narrow size distribution with the average of 235 ± 12 nm. The transmission electron microscopy image showed that liposomes were round in shape and discrete. The release profile exhibited 93% and 71% drug release for PTX and LPT after 40 h in the sink condition. The differential scanning calorimetry analysis indicated the conversion of both drugs from crystalline state to molecular state in the optimized lyophilized formulation. The cytotoxicity of the prepared formulation was studied against 4T1 murine mammary cells. The liposomal formulation showed better cytotoxicity in comparison to the binary mixture of free drugs.