The controlled release drug delivery system possessing the ability of being retained in the stomach is called gastro retentive drug delivery system. They can help in optimizing the oral controlled delivery of drug having “absorption window” continually releasing the drug prior to absorption window for prolong period of time, thus ensuring optimal bioavailability. A floating dosage unit is useful for drugs acting locally in the proximal gastrointestinal tract. These systems are also useful for drug that are poorly soluble or unstable in intestinal fluids. Floating tablets and floating microspheres are common examples of floating system. Microsphere are small spherical particles, with diameters in the micrometer range (typically 1 μm to 1000 μm). Microspheres are characteristically free flowing powders consisting of proteins or synthetic polymers which are biodegradable in nature and ideally having a particle size less than 200 μm. There are various approaches in delivering a therapeutic substance to the target site in a sustained controlled release fashion. One such approach is using microspheres as carriers for drugs.
Amul Mishra, Sweety Rathore, Deepak Marothia and Chauhan CS