ORAL SUSTAINED RELEASE DOSAGE FORM: A REVIEW

Oral drug delivery system is the most prominent and convenient route of administration of drugs.The maintenance of concentration of drug in plasma within therapeutic index is very critical for effective treatment. Factors associated with conventional dosage forms like wide range of fluctuation in drug concentration in the bloodstream and tissues with consequent undesirable toxicity, poor efficiency in treatment, repetitive dosing and unpredictable absorption leads to the concept of oral Sustained release drug delivery systems. Sustained release (SR) products provide an advantage over conventional dosage forms by optimizing biopharmaceutics, pharmacokinetic and pharmacodynamic properties of drugs in such a way that it reduces dosing frequency to an extent that once daily do therapeutic management through uniform plasma concentration providing maximum utility of drug with reduction in local and systemic side effects and cure or control condition in shortest possible time by smallest quantity of drug to assure greater patient compliance. Developing oral sustained release matrix tablets for drugs with constant release rate has always been a challenge to the pharmaceutical technologist. Drug release through matrix system is determined by water penetration, drug dissolution, drug diffusion and matrix erosion. Highly water soluble drugs like Deltiazem, Metformin, and Ranitidine has been formulated as sustained release matrix tablets. This article contains the basic information regarding designing and different approaches for sustained release drug delivery systems. Key Words: Oral drug delivery systems, sustained release, Matrix type systems, patient convenience.