ABSTRACT RESEARCH ARTICLE Int J Pharm Sci Tech ( 2012) © Kinetics of drug release of a guar gum matrix formulation targeting colon, using ibuprofen as a model drug KHIDIR AGAB MOHAMMED HASSAN* Department of Pharmaceutics, Faculty of Pharmacy University of Science and Technology, Omdurman Sudan e-mail: khidiragab@yahoo.com, Mobile phone +249121463935 / + 249900606100, P.O. Box 477 Omdurman, Sudan Background: Concentration of a drug in blood fluctuates over successive administrations of conventional single unit dosage forms. The main reason for this is because conventional dosage forms are designed to release the complete dose of the drug immediately after administration (i.e. burst release effect). These fluctuating drug blood levels can be addressed by means of formulating dosage forms with predetermined drug release profiles. Specific targeting of drugs to the colon has several therapeutic advantages. Drugs which are destroyed by the stomach acid and/or metabolized by pancreatic enzymes are slightly affected in the colon, and sustained colonic release of drugs can be useful in the treatment of nocturnal asthma, angina and arthritis, ulcerative colitis, colorectal cancer and Crohn's disease. Methods: Matrix tablet formulations developed, using different percentages of guar gum, xanthan gum, and microcrystalline cellulose as chemo filler, using ibuprofen as a model drug, were subjected to in vitro drug release studies in simulated colonic fluids (4% w/v of rat caecal contents) obtained after oral treatment of rats for 7 days of 2% w/v guar gum (1 ml) after completing the dissolution study in 0.1 M HCl (2 h) and pH 7.4 phosphate buffer. To study the kinetic of drug release from the developed formulations, the tablets were subjected to a dissolution test at pH 7.4. The different kinetic equations (zero order, first order and Higuchi's equation) were applied to interpret the release rate from matrix system. Results: The best fit with higher correlation was found with Higuchi equation for formulation F19, F21 (r =0.998 and 0.993 respectively). Zero order for formulation F19, F21 (r =0.996 and 0.992 respectively), and first order for F21, F26 (r=0.986 and 0.975 respectively). Conclusion: Higher polymeric content of guar gum (70%) decreased the release rate of drug because of the increased swelling rate and decreased erosion rate Key words: drug targeting, matrix tablet, guar gum, drug release, in vitro-dissolution Vol-8, Issue - 2, July - December 2012 Vol-8, Issue - 2, July - December 2012