Inorganic nanoparticles for oral drug delivery: opportunities, barriers, and future perspectives

Oral delivery is the preferred route of drug administration due to patient compliance and convenience. Despite this, nanomedicines have so far primarily been developed for the parenteral route. Inorganic nanoparticles hold great promise as theranostics for oral drug delivery. This is gaining importance especially for the local treatment of gastrointestinal (GI) diseases. However, successful oral delivery of inorganic nanoparticles is challenged by complex physiological conditions in the GI tract. We discuss the main GI barriers and their impact on nanoparticle biotransformation and toxicity. An improved understanding of the complex interplay of inorganic nanoparticles with the dynamic GI environment can facilitate the development of efficient oral nanomedicines.