Spray-drying of poly(anhydride) nanoparticles for drug/antigen delivery

Gantrez AN nanoparticles can be obtained by desolvation of the poly(anhydride) with an aqueous medium, followed by a purification step and freeze-drying. In order to simplify this method, a spray-drying procedure was evaluated here. For this purpose, suspensions of nanoparticles were mixed with carbohydrates before their drying. Lactose, in a saccharide/polymer ratio of 2, was found to be the most suitable excipient regarding the physicochemical characteristics and stability of the resulting nanoparticles. These conditions can be successfully applied to the preparation of conventional, combined cyclodextrin/polyanhydride or pegylated nanoparticles. The capabilities of the new procedure were also studied by the characterization of nanoparticles loaded with either an antigenic extract (HS from Brucella ovis) or atovaquone. In all cases, the new formulations displayed similar physico-chemical characteristics to those of nanoparticles obtained by lyophilization. In summary, the spray-drying procedure can be an adequate alternative to lyophilization in the preparative process of poly(anhydride) nanoparticles.