Design and in vitro evaluation of a novel poly(methacrylic acid)/metronidazole antibacterial nanogel as an oral dosage form

•Poly(methacrylic acid) (PMAA) nanogels were prepared to load metronidazole (MTZ).•MTZ/PMAA nanogels sustained the release of MTZ in simulated gastrointestinal medium.•MTZ/PMAA nanogel showed long-term antibacterial activity.•AM/PMAA nanogel showed slighter cytotoxicity than AM alone.

To overcome the undesirable side-effects of metronidazole (MTZ), ethylene glycol dimethacrylate is used as the cross-linker, and a series of poly(methacrylic acid) (PMAA) nanogels were prepared to load the MTZ. We investigated the morphology, size, in vitro release property in the simulated gastrointestinal medium, long-term antibacterial performance against Bacteroides fragilis, cytotoxicity, stability and activity of this novel MTZ/PMAA nanogel. The results indicate that the MTZ/PMAA nanogel sustained the release of MTZ in long-term antibacterial activity in the simulated gastrointestinal medium. This MTZ/PMAA nanogel exhibits less cytotoxicity than MTZ alone, suggesting that MTZ/PMAA nanogel is a more useful dosage form than MTZ for mild-to-moderate Clostridium difficile infections. The novel aspects of this study include the synthesis of a nanogel and the three-phase study of the release profile, which might be useful for other researchers in this field.

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