Study On Konjac Glucomannan And Carboxymethyl Konjac Glucomannan As Carrier Materials Used In Oral Colon-Specific Drug Delivery System

Oral colon-specific drug delivery systems(OCDDS) have been the hot spot of new oral drug delivery systems being investigated for the last two decades. OCDDS are designed to decrease drug release in the upper digestive tract and release mainly drug when they arrive at cecocolon, for the local treatment of bowel diseases and for improving systemic absorption of the drugs which are susceptible to enzymeatic digestion in the upper gastrointestinal tract (GIT). Four strategies are being pursued to achieve colon-specific drug delivery, which are pH-controlled, time-controlled, pressure-controlled and enzyme-controlled. Among them, the first three strategies are subject to the risks related to the variability in GIT conditions, such as pH, transit times and intestinal pressure, which can lead to premature and non-specific drug delivery in the colon. Enzyme-controlled systems are known as microbially controlled systems, which can be formulated utilizing some specific property of the colon, such as microflora becomes diverse and luxurian, in comparison to the other parts of the GIT, the microflora produces a vast number of enzymes. Because of the presence of these biodegradable enzymes only in the colon, enzyme-controlled systems seem to be a more site-specific strategy as compared to other strategies.Konjac glucomannan (KGM) is a high-molecular weight water-soluble non-ionic polysaccharide derived from tubers of Amorphophallus rivieri. It has been used in food and pharmaceutical industry etc. The resource and yield of Amorphophallus konjac in our country is the first of the world, but it is deficiency for its deep processing and application. So it is the key for utilizating its resource that how to develop its new application route. Since KGM can be degraded by β-glucosidase existed in cecal and colon, but not by digestive enzymes of the upper disgestive tract, it could be used as carrier materials to prepare OCDDS. But the selectivity of preparation categories were narrow because of the properties of KGM such as non-ionic and high swelling nature, so KGM was chemical modified to expand its selectivity.