A REVIEW ON GASTRO RETENTIVE DRUG DELIVERY SYSTEM (GRDDS) WITH SPECIAL EMPHASIS ON FORMULATION AND DEVELOPMENT OF FLOATING MICROSPHERES Review Article

The goal of any drug delivery system is to provide a therapeutic amount of drug to the proper site in the body to achieve promptly and then maintain the desired drug concentration. The most convenient and commonly employed route of drug delivery is by oral ingestion. But drugs that are easily absorbed from the GIT and having a shorter half-life are eliminated quickly from the blood circulation. To avoid these problems oral controlled drug delivery systems have been developed as they release the drug slowly into the GIT and maintain a constant drug concentration in the serum for longer period of time. However, incomplete release of the drug and a shorter residence time of dosage forms in the upper gastrointestinal tract, a prominent site for absorption of many drugs, will lead to lower bioavailability. Therefore efforts to improve oral drug bioavailability have grown in parallel with the pharmaceutical industry. Gastro retentive dosage forms, which prolong the residence time of the drugs in the stomach and improve their bioavailability, have been developed. They are primarily controlled release drug delivery systems, which gets retained in the stomach for longer periods of time, exhibiting an absorption window and thus useful for the spatial and temporal delivery of many drugs. The present review describes the Gastro Retentive Drug Delivery System (GRDDS) with special emphasis on Floating Microspheres, its preparation methods, advantages as a drug delivery system and useful formulation ingredients.