Chitosan as floating-mucoadhesive polymers in gastroretentive drug delivery

Oral drug delivery is limited by incomplete absorption in the digestive tract. The absorption of oral drugs in the stomach is affected by several factors, including gastric residence time, which causes the drug to be unable to be retained in the stomach for a long time, causing suboptimal drug absorption. One of the drug delivery systems that can prolong contact duration within the stomach is gastroretentive drug delivery system (GRDDS). GRDDS has various advantages, notably in improving the bioavailability of drugs. Several systems are involved in the GRDDS, including the floating and mucoadhesive systems. The floating system makes the drug float so it can be retained longer in the stomach. There are two mechanisms in the floating system: the effervescent and non-effervescent mechanisms. The mucoadhesive system works by adhering to the mucus or epithelial cells of the stomach. The mechanisms of mucoadhesive systems involves two stages: the contact and consolidation stages. The combination of the floating and mucoadhesive systems is aimed to improve the efficiency and effectiveness of a preparation for prolonged retention in the stomach. The choice of polymer is one of the crucial factors affecting this system. Chitosan is a natural polymer that has been evaluated for its potential in a gastroretentive floating beads delivery system. It has various advantageous properties, such as non-toxicity, biocompatibility, and biodegradability.