Successful drug therapy depends upon the selection of suitable drug as well as the selection of suitable composition. The research and development involved in the formulation of new product should develop a dosage form which is technically and biopharmaceutical optimal. Most of the drug formulations deliver the drug to systemic circulation which is not controlled by the dosage form.Over the past 40 years, as the expense and complications involved in marketing new drug entities have increased, with concomitant recognition of the therapeutic advantages of controlled drug delivery, greater attention has been focused on development of oral sustained or controlled release drug delivery systems. There are several reasons for the attractiveness of these dosage forms. The goal in designing sustained or controlled delivery system is to reduce the frequency of dosing or to increase the effectiveness of the drug.