Gastroretentive drug delivery systems: A review

Oral administration has only limited use for important drugs from various pharmacological categories, that have poor oral bio-availability due to incomplete absorption and/or degradation in the gastrointestinal tract (GIT). Drugs that are easily absorbed from the gastrointestinal tract (GIT) and have a short half-life are eliminated quickly from the blood circulation, so they require frequent dosing. To avoid this drawback, the oral sustained-controlled release formulations have been developed in an attempt to release the drug slowly into the gastrointestinal tract (GIT) and maintain an effective drug concentration in the serum for longer period of time. However, such oral drug delivery devices have a physiological limitation of gastric retention time (GRT), variable and short gastric emptying time can result in incomplete drug release from the drug delivery system (DDS) in the absorption zone (stomach or upper part of small intestine), leading to diminished efficacy of the administered dose. 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. This idealized objective points to the two aspects most important to the drug delivery; namely spatial placement and temporal delivery of a drug. Spatialplacement relates to targeting a drug to a specific organ or a tissue while temporal delivery refers to controlling the rate of drug delivery to that specific organ or a Tissue. Key words: Gastroretentive, drugdelivery, controlled.