Gastric residence time

Gastro retentive drug delivery system is benefited system in which dosage form retained in stomach prolong period of time and drug release long period of time. Floating system means that float over the surface of the gastric contents when the stomach is full but at the time stomach is empties and the tablet reaches the pylorus the buoyancy of the dosage may be decrease & bioadhesive system becomes dislodged from the stomach wall when the system is full but a floating -bioadhesive system would overcome these drawback of floating and bioadhesive system and improving the therapeutic effect of the drug involved.   So this Floating-bioadhesive dosage forms exhibit a unique combination of floatation and adhesion for prolonged residence in the Stomach. Currently this floating bioadhesive approach is not only used for tablets but also for microsphere, beads & other dosage forms. This review article focus on recently used combination approaches to deliver drug by gastrointestinal drug delivery like Bioadhesive and floating.

In the present study we have developed a non-effervescent gastro retentive dosage form containing pantoprazole sodium by emulsion solvent diffusion method. A 23 full factorial design was used for the optimization process and the various responses obtained were evaluated by fitting in the binomial equations. Formulations ERS 1-8 were made utilizing three independent variables such as amount of crospovidone (%), Eudragit®E100 (mg) and Eudragit®RS100 (mg) which were varied at low and high levels and are evaluated for percentage buoyancy, entrapment efficiency and cumulative drug release after 5 h in buffer pH 2.2. The experimental values of the optimized formulation ERS-O coincides well with the predicted values obtained from optimization technique. Design expert 9.0.3 predicts responses as % buoyancy of 75.04±0.05, % entrapment efficiency of 87.57±0.21 and cumulative drug release after 5 h of 97.93±0.15 which were close to the actual values validates the design. The optimized formulation were in size range 20-120 µm with spherical shape, internal hollow cavity and porous boundary wall, moreover only physical cross-linking occurred with zero order release pattern and the in vivo analysis through ethanol induced ulceration method gave better ulcer healing orally than the intravenous route.

In the recent years, scientific and technological advancements have been made in the research and development of novel drug delivery systems by overcoming physiological troubles such as short gastric residence times and unpredictable gastric emptying times. Several approaches are currently utilized in the prolongation of the gastric residence times, including floating drug delivery systems, swelling and expanding systems, polymeric bioadhesive systems, modified-shape systems, high-density systems and other delayed gastric emptying devices. This review entitled the detailed scenario related to Bilayer floating drug delivery system with their advantages over the conventional drug delivery system and also limitation, which are helpful in development of dosages form. Various types of techniques employed for development of this dosages form. Review focused on formulation aspect of effervescent floating drug delivery system with their evaluation techniques. The purpose of this comprehensive review is to compile the work going on this delivery system. Which provide the valuable information related to formulation aspect to achieve gastric retention and discussed the various factors affect and to overcome it

Gastric emptying is a complex process and makes in vivo performance of the drug delivery systems uncertain. Floating Bilayer drug delivery system is combined principle of bilayer tablet as well as floating mechanism. Floating drug delivery system provides advantages local delivery to specific region like stomach and proximal small intestine and it’s also shows better bioavailability and improved therapeutic activity. Floating Bilayer tablet is suitable for sequential release of two drugs in combination, separate two incompatible substances and also for sustained release tablet in which one Layer is immediate release as initial dose and second layer is maintenance dose. The purpose of this paper is to review the concept of Floating Bilayer drug delivery systems with the recent literature and current technology used in the development of Floating Bilayer drug delivery system as well as summarizes evaluation method and applications of various floating dosage forms. Key words: - Bilayer Floating drug delivery systems, Gastric residence time, Swelling index, Buoyancy