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 (2012)

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. The coating not only used for targeting Mesalamine to colon but also used for targeting of many bio active compounds, harmones, proteins such as insulin,calcitonin,vasopressin,antibiotics, vaccines can also targeted to the colon by using Pectin-HPMCE15LV coating systems. Prophylaxis to nicotine addiction and treatment of colonic cancer also possible by this coating by targeting the suitable candidates to colon. The simple manufacturing of tablets with suitable drug or bio-active material or simply filling it in the capsule by using a capsule filling machine and coating them with the present natural coating systems by using regular coating technique and machine the scale up can be developed easily for the large scale manufacturing. Keywords. Colon; inflammatory bowel disease; pectin; Eudragit L 100; Mesalamine