Sinking-magnetic microparticles prepared by the electrospray method for enhanced gastric antimicrobial delivery

A targeted oral drug delivery system is useful to improve the treatment of gastrointestinal diseases. A high density sinking dosage form can sink to the bottom of the stomach near the pylori sections to enhance gastric retention. However, it is difficult to achieve a high density sinking system using the traditional technology. In the current study, novel stomach-specific sinking magnetic microparticles (SMMPs) were prepared via the monoaxial electrospray method for enhanced gastric antimicrobial delivery. The size of SMMPs was approximately 5 μm, and the Fe3O4 nanoparticles were observed in the SMMPs by transmission electron microscopy (TEM). The density of SMMPs increased as the concentration of Fe3O4 nanoparticles in the electrospray inlet flow increased, with the maximum true density of approximately 3.52 g/cm(3). The SMMPs displayed strong magnetism in vitro and in vivo. They can settle down in water within 120 s in vitro, and the settling time decreased to 20 s under a magnetic field. Furthermore, an in vivo γ scintigraphy study demonstrated that (131)I labeled SMMPs were retained in the stomach for over 8 h, and an external permanent magnet can increase their gastric retention time even further. Using Helicobacter pylori as a model bacterium, amoxicillin-loaded SMMPs exhibited a significantly greater eradication of H. pylori compared to the free drug, in vivo. Our results suggested that electrospray is an effective technique to prepare the high density gastroretentive dosage forms. We have shown that stomach-specific SMMPs can supply better treatment for H. pylori infections and have the potential to be used in clinical practice.