**4.1 Modified formulations of PTX**

Because of the unfavorable properties of PTX, it is urgent to develop a more effective strategy to improve its water solubility and selectivity towards tumor tissues (Maeda et al., 2009). Several approaches have been utilized to increase the therapeutic index of PTX. More water-soluble formulations of PTX have been investigated, including a nanoparticulate formulation (ABI-007), a polymeric micellar formulation (Genexol-PM), and a liposomal formulation and covalent linkage to macromolecule polymers that alter the pharmacokinetics of the parent drug (Ibrahim et al., 2002; Kim et al., 2004; Soepenberg et al., 2004).
