Applied Design
Applied Design
Because the bacteria need to survive in people’s colon, we need to make sure that the bacteria are able reach there without breakdown. Therefore, in our project we designed a capsule with our product in mind. For this aim, the bacteria need to be protected from absorption and injury in the gastrointestinal tract upstream of the colon. Subsequently, the bacteria need to be released immediately. There are various approaches such as designing a capsule coating that can be degraded at above-neutral pH, or that will be degraded after a predetermined time. According to previous studies, some plant polysaccharides such as amylose, inulin, pectin and guar gum are able to withstand the chemical insults of the gastrointestinal tract so that we can deliver the bacteria to the colon more easily. What’s more, because the pH of the gastrointestinal tract is gradually higher, the pH value can also be a control factor in our coating design. Time-dependent drug delivery is also an acceptable method, but there are some drawbacks. Because the time until foods passes through the digestive system and reaches colon is about 6 hours, and this time will change when people eat different foods, people need to control the food type they eat when they are taking our bacteria. Therefore, coating with pH-sensitive polymers is a better choice. We found a previous study that used acrylic resin as main material for pill coatings. The more hydroxy groups there are, the higher the pH value the coating can withstand, because the hydroxy groups will not be dissolved at low pH values. When the pH increases, the polymers are ionized and dissolved. This way, we can achieve successful colonic delivery.
Reference
M. K. Chourasia, S. K. Jain, Pharmaceutical approaches to colon targeted drug delivery systems , J Pharm Pharmaceut Sci, 33-66, 2003.
