Pectin-HPMC E15LV Vs pH sensitive polymer coating films for delayed drug delivery to colon: a comparison of two dissolution models to assess colonic targeting performance in-vitro

Summary.The study was designed to evaluate the in vitro dissolution characteristics comparatively between pH sensitive polymer coated tablets and natural polymer coated tablets in a various simulated fluids (pH values 1.2, 6, 6.8, 7.2, 5). The fabricated Mesalamine tablets were coated with pectin-HPMC(Hydroxy propyl methyl cellulose) E15LV (FC1-FC5) in combination and with Eudragit L100 ( FC6-FC10)separately. Different buffer conditions were chosen to mimic the pH changes of the terminal part of the ileum as well as the colon. Two in vitro studies were conducted separately in all the formulations. The impact of the pH changes on the coated tablets in normal pH condition and reduced pH condition (which occurs during inflammation in the colon) were compared. The results showed that the impact of pH changes on the release profile of Eudragit L100 coated tablets was significant in reduced pH condition. In pH sensitive polymer coated tablets, drug release characteristics and the rate were affected when compared to the pectin coated tablets. This study indicates that poly methacrylate polymers could not release the drug in predetermined rate in a variety of pH conditions. The present treatment methods of inflammatory bowel disease (IBD) mostly depend on pH sensitive polymers. These pH sensitive polymers based colonic devices may not serve the patient need successfully because the influence of colonic pH on pH sensitive polymers plays an important role in drug release. The lowered pH condition in diseased state could not trigger the drug release, as it was not the threshold pH of the particular coated polymer. Therefore, in such diseased conditions natural polymer (pectin)based devices serve better for the objective of the therapy. The study on the effect of pH changes on the drug release profile of natural polymer-based colonic devices revealed that there was no impact by pH changes on the devices since they release the drug by the effect of colonic bacteria and not by the pH sensitivity. Industrial relevance. Targeting the drugs to colon is the most important aspect of modern IBD therapy. The coating is the most widely used smple technique in the industry. The present coating techniques available for the colon targeting with pH sensitive polymers for colonic delivery can be successfully replaced by the pectin-HPMC E15 LV coating. This coating can be given by the usal coating machine used in the industry. The difficulty found in coating with polysaccrides polymers were successfully solved by the incorporation of HPMC premium polymer in the coating formula