Studies on Release Characteristics of Various Natural Polymers on Buccal and Colon Delivery Systems

Abstract

Polymers can be naturally occurring, synthetic or a combination of both. The natural polymers have the ability to act as substrates for the bacterial inhabitants of the colon together with their properties such as swelling, film forming, bio adhesion, biocompatibility and biodegradability. These properties have initiated their use as colon carrier and bio adhesive polymers. They are found in abundance with wider availability, inexpensive and available in a variety of structures and properties. They can be easily modified chemically, highly stable, safe, nontoxic, which suggests their use in various delivery systems. Oral administration of drugs have disadvantages such as hepatic first pass metabolism and enzymatic degradation within the GI tract that prohibit oral administration of certain classes of drugs especially proteins and peptides. The buccal route is a valid alternative to the oral one and offer many advantages. In particular, it improves the drug bioavailability due to avoidance of first pass metabolism and of degradation in the gastrointestinal tract. Buccal delivery necessitates the use of muco-adhesive polymer as an excipient in dosage form which ideally adheres to the mucosa and withstands salivation. Colon delivery system has gained importance due to less diversity and intensity of enzymatic activities and near neutral pH. In addition, the dosage form stays longer in the colon and avoids first pass metabolism. The best approach available for colon specific drug delivery is the use of carriers that are degraded exclusively by colonic bacteria. The present investigation was aimed to evaluate the suitability of various natural polymers for buccal and colon specific drug delivery and also to study the release characteristics of the polymers. For buccal delivery, various natural polymers such as flax seed polymer, locust bean gum, moringa gum were selected and chitosan was included at various weight ratios. Nifedipine and propranolol HCI were selected as model drugs since both exhibits higher first pass metabolism.