A REVIEW ON AN EMERGIN TREND BILAYER FLOATING DRUG DELIVERY SYSTEM

NDDS is advanced drug delivery system which improves drug potency, control drug release to give a sustained therapeutic effect, provide greater safety, finally it is to target a drug specifically to a desired tissue. Novel drug delivery system have been developed to overcome the limitation of conventional drug delivery systems, such as of gastric retention by decreasing fluctuations in the concentration of the drug in blood,resulting in the reduction in unwanted toxicity and poor efficiency. As compared to traditional dosage forms bilayer tablets are more efficient for sequential release of two drugs that can be different or identical. Bilayer tablet is also capable of separating two incompatible substances and also for sustained release. Gastro retentive drug delivery system retains the period of dosage forms in the stomach or upper gastro intes-tinal tract ,as to improve bioavailability and the therapeutic efficacy of the drugs. Mainly the bilayer drug delivery system is suitable for drugs whose therapethic windows are narrow in the gastrointestinal tract (GIT) and also they have low elimination half life: 3-4 h. The purpose of this review is to disclose the challenges faced during the formulation of bilayer tablets. Finally, the whole article is firmly analyzed in a concluding paragraph. KEYWORDS: Conventional drug delivery systems, Bilayer tablet, Gastro retentive, Bioavailability