The high level of patient compliance in taking oral dosage forms is due to the ease of administration and handling of these forms [1]. Development of a successful oral controlled release formulation requires an understanding of three aspects: (a) gastrointestinal physiology (b) physiochemical properties of the drug and (c) dosage form characteristics [2]. In the development of oral controlled drug delivery system, one of the main challenges is to modify the GI transit time [1]. Using controlled release technology, oral delivery for 24 h(hours) is possible for many drugs; however, the substance must be well absorbed throughout the whole gastrointestinal tract. A significant obstacle may arise if there is a narrow window for drug absorption in the gastro intestinal tract (GIT), if a stability problem exists in gastrointestinal fluids, or the drug is poorly soluble in the intestine or acts locally in the stomach. Thus, the real issue in the development of oral controlled release dosage forms is not just to prolong the delivery of the drugs for more than 12 h, but to prolong the presence of the dosage forms in the stomach or somewhere in the upper intestine until the entire drug is released over the desired period of time [3].
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