-Conventional drug delivery systems have slight control over their drug release and almost no control over the effective concentration at the target site. This kind of dosing pattern may result in constantly changing, unpredictable plasma concentrations. Drugs can be delivered in a controlled pattern over a long period of time by the controlled or modified release drug delivery systems. They include dosage forms for oral and transdermal administration as well as injectable and implantable systems. For most of drugs, oral route remains as the most acceptable route of administration. Certain molecules may have low oral bioavailability because of solubility or permeability limitations. Development of an extended release dosage form also requires reasonable absorption throughout the gastro-intestinal tract (GIT). Among the available techniques to improve the bioavailability of these drugs fabrication of osmotic drug delivery system is the most appropriate one. Osmotic drug delivery systems release the drug with the zero order kinetics which does not depend on the initial concentration and the physiological factors of GIT. This review brings out new technologies, fabrication and recent clinical research in osmotic drug delivery. __________________________________________________________________________________________

The intracellular residence of the Leishmania parasite in the cells of the reticuloendothelial system--predominantly the liver and spleen--prompted the development of a polymeric, particulate, colloidal carrier system for the antileishmanial drug sodium stibogluconate. The system was pharmaceutically characterized for shape, size, structural integrity, electrokinetic properties and in vitro drug release. The relationship between such physical parameters as size, electrophoretic mobility and surface charge and the effectiveness of the system is discussed. Subsequent in vivo studies in rats revealed that the carrier system successfully vectored the drug to the site of infection.

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The aim of present study was to prepare buffered tablets of acid labile drug, Rabeprazole sodium for oral administration using buffering agents to protect a drug from gastric fluid. Rabeprazole belongs to a class of antisecretory compounds (substituted benzimidazole proton-pump inhibitors) that do not exhibit anticholinergic or histamine H2-receptor antagonist properties, but suppress gastric acid secretion by inhibiting the gastric H+, K+ATPase at the secretory surface of the gastric parietal cell. Rabeprazole blocks the final step of gastric acid secretion. The tablets were prepared by direct compression and wet granulation method. The formulations contain water soluble buffers such as sodium bicarbonate and trisodium phosphate as well as water insoluble buffers as magnesium oxide, magnesium hydroxide and calcium carbonate and crospovidone as superdisintegrant. Preformulation studies like angle of repose, bulk density, tapped density, Carr’s index, hausner’s ratios, DSC and drug/excipient compatibility study were conducted and evaluated for hardness, friability, weight variation, drug content, disintegration and in-vitro dissolution. In the present study, pH of F6 batch was found to be optimum and disintegration time is 42 sec. The drug release was found to show maximum drug release in case of F6 with 99.3% in 60 minutes. In case of stability studies study of the optimized batch, all the results were found to be satisfactory and within limits. There were no significant changes after the period of 1 month study. Keywords: Rabeprazole sodium, Proton-pump inhibitors, Buffered tablet, Superdisintegrants, Buffering agents