Nanoparticle-coated microparticles: preparation and characterization.

The objective of the present work was to design and prepare new nanoparticle-coated drug-loaded inorganic microparticles by spray-drying using diclofenac as drug model. Previous works presented the process to dry drug-loaded polymeric nanoparticles using silicon dioxide as adjuvant, otherwise in the present proposition the drug is associated with the silicon dioxide and unloaded polymeric nanocapsule or nanosphere suspensions were used as organic coating. Eudragit S100 was chosen because of its gastric resistance. The potential application of polymeric colloidal suspensions as nanocoating for microparticles were evaluated in terms of process yields, encapsulation efficiencies, morphologic analyses and in vitro drug release profiles in buffered media (pH 1.2; 5.0 and 7.4). The results showed the technological feasibility of preparing controlled nanoparticle-coated drug-loaded inorganic microparticles. When the diclofenac was employed as a hydrophilic model, in this salt form, the powders prepared in two steps (core previously prepared) showed an adequate gastroresistance by the use of Eudragit S100. The use of diclofenac as a hydrophobic model (acid form) conducted to powders presenting good gastroresistance when the nanocapsules and triacetin were employed.