multiple units

The purpose of writing this review on floating drug delivery systems (FDDS) was to compile the recent literature with special focus on the principal mechanism of floatation to achieve gastric retention. The aim of writing this review on gastro retentive and floating drug delivery system was to compile the new literature with the principle mechanism of floatation to acquired gastric retention. The methodologies used in the development of FDDS by formulating effervescent and non effervescent floating tablets based on buoyancy mechanism. FDDS are of particular interest for drugs that are locally active and have narrow absorption window in stomach or upper small intestine, unstable in the intestinal or colonic environment, and exhibit low solubility at high pH values. This review article is in pursuit of giving detailed information on the pharmaceutical basis of their design, classification, advantages, in vitro evaluation parameters. Controlled release (CR) dosage forms have been extensively used to improve therapy with several important drugs. The recent developments of floating drug delivery systems (FDDS) including the physiological and formulation variables affecting gastric retention, approaches to design single-unit and multiple-unit floating systems, and their classification and formulation aspects are covered in detail. This review also summarizes the in vitro techniques, in vivo studies to evaluate the performance and application of floating systems. Floating dosage form can be prepared as tablets, capsules by adding suitable ingredients as well as by adding gas generating agent. In this review various techniques used in floating dosage forms along with current & recent developments of stomach specific floating drug delivery system for gastro retention are discussed.

  This review explains the recent advances in gastroretentive drug delivery systems with special focus on floating drug delivery systems. Oral controlled release (CR) dosage forms (DF) have been extensively used to improve therapy of many important medications. However, in the case of narrow absorption window drugs, this pharmaceutical approach cannot be utilized, as it requires sufficient colonic absorption of the drug (which contradicts the definition of narrow absorption window agents). On the other hand, incorporation of the drug into a CR delivery system, which releases its payload in the stomach over a prolonged time period, can lead to significant therapeutic advantages owing to various pharmacokinetic (PK) and pharmacodynamic aspects. Gastroretentive dosage forms (GRDFs) are a drug delivery formulation that are designed to be retained in the stomach for a prolonged time and release there their active materials and thereby enable sustained and prolonged input of the drug to the upper part of the gastrointestinal (GI) tract. This technology has generated enormous attention over the last few decades owing to its potential application to improve the oral delivery of some important drugs for which prolonged retention in the upper GI tract can greatly improve their oral bioavailability and/or their therapeutic outcome. This article reviews some of the latest developments in GRDF technology from a pharmaceutical point of view. It also highlights the PK and/or pharmacodynamic rationale for the development of GRDFs for certain drugs that are either absorbed in the upper GI tract or have local activity there.   Key words: Floating drug delivery systems, single unit, multiple units, gastric resident time, Expandable Systems