Nanoparticle infiltration to prepare solvent-free controlled drug delivery systems.

The purpose of this work was to propose a drug delivery system based on a biodegradable porous membrane, whose surface is covered by a nanoparticle film, thus achieving a controlled drug release rate. Furthermore, due to the fact that the assembly of the system is performed in aqueous medium, contact with organic solvents is avoided. The method is performed in two steps: (i) preparation of biodegradable porous membranes (by a solvent casting and particulate leaching technique) and biodegradable nanoparticles (by the emulsification-diffusion method), extensively eliminating the solvent in both of them; (ii) infiltration into membranes of an aqueous solution of a model drug (carbamazepine) and a nanoparticle dispersion. In both cases, poly(DL-lactic-co-glycolic acid) (PLGA 50:50) was used as a biodegradable polymer. Carbamazepine adsorbed onto biodegradable porous membranes shows an immediate release behavior (95% released in <15 min). Infiltration of different amounts of nanoparticles (50, 100, 400 and 600 mg of nanoparticles/0.625 g of membrane) into biodegradable porous membranes shows a Fickian diffusion according to Peppas model, and fits Higuchi's model. This behavior was attributed to the diffusional barrier constituted by the nanoparticle film. As expected, the carbamazepine release rate was dependent on the amount of infiltrated/adsorbed nanoparticles into biodegradable porous membrane. DSC studies show molecular dispersion of the drug throughout the membrane.