pH-sensitive microparticles for oral drug delivery

This article shall give an overview on pH-sensitive microparticulate drug delivery systems with a main focus on their application in oral drug administration. It deals with the major therapeutic strategies to which such microparticles can be applied mainly based on the selective drug delivery towards specific areas in the gastrointestinal tract. Beside taste masking pH-sensitive microparticles have been used for the avoidance of gastric irritation. Most of the approaches described in literature however, aim for the increase of bioavailability of the entrapped drug. For the increase of oral bioavailability of fragile drugs, such as peptides or proteins, pH-sensitive microparticles are intended to protect the entrapped drug load against its degradation in the upper intestinal tract and to deliver it in a more advantageous environment. In a similar way, microparticles have proved their efficiency for oral vaccination. In addition to the above mentioned delivery strategies targeting the most promising absorption site, other therapeutic approaches aim for selective local drug delivery, especially for applications in inflammatory bowel disease. This overview of the different applications of pH-sensitive microparticles for oral administration emphasizes their versatility and underlines that they may be an interesting tool in order to open new therapeutic pathways for a large diversity of diseases.