Oral drug delivery is the most widely utilized route of administration among all the routes that has been used for the systemic delivery of drugs via various pharmaceutical products of different dosage form. Nowadays most of the pharmaceutical scientists are involved in developing an ideal DDS, this ideal system should have advantage of single dose for whole duration of the treatment and it should deliver the drug directly at specific target site. Scientists have succeeded to develop a system that can be as near to an ideal system and it encourages the scientist to develop controlled release system. The design of oral sustained drug delivery system should be aimed to achieve the more predictability and reproducibility to control the drug release, drug concentration in the target tissue and optimization of the therapeutic effect of a drug by controlling its release in the body with lower and less frequent dose. For most of the drugs, conventional methods of formulation are quite effective. However some drugs are unstable and toxic and have a narrow therapeutic range, exhibit extreme solubility problems, require localization to a particular site in the body or long-term use. In such cases a method of continuous administration of drug is desirable to maintain fixed plasma drug levels[1]. To develop the ideal drug delivery system, two prerequisites is to be required. First, it would be single dose for whole duration of treatment, whether it is for days or weeks or for the lifetime of patient, as in hypertension or diabetes. Second, it should deliver the active entity directly to the site of action, thereby minimizing or eliminating adverse effects. This may necessitate delivery to specific receptors or to localization to cells or to specific areas of the body. Ideally a drug to provide desired therapeutic action should arrive rapidly at the site of action in optimum concentration, remain there for desired time and get removed from the site. One of the interesting results of pharmaceutical research is the fact by reducing the release rate of a drug from the dosage form its absorption rate can be decreased. The products so formulated are named as sustained action, sustained release, delayed action, prolonged action, depot, repository, retarded release and time release medication [2]