A REVIEW OF ORAL MATRIX TYPE CONTROLLED DRUG DELIVERY SYSTEM M. Hareesh Reddy *1 , Dr. A. Sambasiva Rao

The goal in designing sustained or controlled delivery systems is to reduce the frequency of the d osing or to increase effectiveness of the drug by localization at the site of action, reducing the dose required or p roviding uniform drug delivery. Polymers which are used as release retarding materials in the design of controlled release drug delivery sy stems (CRDDS) play a vital role in controlling the delivery of drug from these systems. The success of controlled release drug delivery systems depends on how well the polymer regulates the release of drug from the system. In conventional drug therapy, a tablet provides only a single and transient burst of drug .It doesn’t maintain drug blood level with in therapeutic range for extended period of time. The short duration of action is due to the inability of conventional dosage form to control the temporal delivery. As long as the amount of drug is above the minimum effective concentration, a pharmacological response is observed. Problems occur when the therapeutic range is very narrow or when the peak is beyond the upper limit of range. The oral route is th e route most often used for administration of drugs. Tablets are the most popular oral formulations available in the market and are preferred by patients and physicians alike. In long - term therapy for the treatment of chronic disease conditions, convention al formulations are required to be administered in multiple doses and therefore have several disadvantages. Sustained release dosage forms have been demonstrated to improve therapeutic efficiency by maintenance of a steady drug plasma concentration. The us e of polymers in controlling the release of drugs has become an important tool in the formulation of pharmaceutical dosage forms. Sustained release can be achieved by formulating drugs as matrix devices using HPMC, Sodium CMC and other swellable polymer. A lso the matrix tablets are easy to prepare and they are cost effective and exhibit predictable release behavior. Key Words : Controlled drug delivery systems ( CRDDS) , Matrix tablet, HPMC, Sodium CMC, Swellable polymer