Polymer micelles solid dispersion method

The solid dispersion method (Fig. 2B) was used for solubilization of paclitaxel into PEG-poly(D,L-lactide) diblock copolymer micelles. Paclitaxel and the polymer were dissolved in acetonitrile followed by evaporation of the solvent under a stream of nitrogen at 60°C to obtain a gel-like polymer-drug matrix. Dissolution of the solid matrix in water at about 60° C with stirring led to formation of drug-loaded micelles. Because a heating is needed to completely dissolve the polymer-drug matrix, this method may not be not desirable for thermally unstable drugs. 

The nature of the interactions between polymers in a blend depends strongly on the physical state of the system. It is well known that polymers are generally incompatible in the solid state films cast from a solution containing a mixture of polymers are, in fact, usually opaque. It has been shown by microscope methods that incompatible pairs can, in certain cases, be included in a two-phase system [319]. One polymer tends to form a continuous phase while the other is dispersed in that continuous phase in the form of micelles of dimension (1—15) x 10 4 cm. The polymer blends described next have been obtained by freezedrying a solution of the mixture (Richards and Salter [320]) or by casting films from solutions (McNeill et al. [321—325]). Their physical state is, however, not defined. 

---