Floating microspheres as drug delivery system: newer approaches.

A controlled drug delivery system with prolonged residence time in the stomach can be of great practical importance for drugs with an absorption window in the upper small intestine. The main limitations are attributed to the inter- and intra-subject variability of gastro-intestinal (GI) transit time and the non-uniformity of drug absorption throughout the alimentary canal. Floating drug delivery systems (FDDSs) are expected to remain buoyant in a lasting way upon the gastric contents and consequently to enhance the bioavailability of drugs. The various buoyant preparations include hollow microspheres, granules, powders, tablets, capsules, pills and laminated films. Floating microspheres are specially gaining attention due to their wide applicability in the targeting of drugs to stomach. These floating microspheres have the advantage that they remain buoyant and distributed uniformly over the gastric fluid to avoid the vagaries of gastric emptying and release the drug for prolonged period of time. A major drawback of low-density floating drug delivery systems is that their performance is strongly dependent upon the gastric emptying process of stomach. Multiparticulate low-density particles can successfully prolong the gastric retention time of drugs. This article is a review of two important approaches utilized to prepare and improve the performance of floating microspheres.