The present study was undertaken with an aim to develop and evaluate gastroretentive floating tablets of Metronidazole that are designed to retain in the stomach for a long time and have developed as a drug delivery system for better eradication of Helicobacter Pylori in peptic ulcer diseases. The floating tablets of Metronidazole were made by direct compression method using polymer Carbopol 934 and sodium bicarbonate and citric acid as gas generating agent. The tablets were evaluated by pre and post compression parameters such as weight variation, thickness, friability, hardness, drug content, in-vitro buoyancy studies and in-vitro dissolution studies and results were within the limits. Hardness was found to be in the range of 7.6 ± 0.27 kg/ cm² to 7.9 ± 0.35 kg/cm², the percent friability was in the range of 0.48% to 0.52% w/w and the tablets showed 94% to 97% uniformity in drug content. The in-vitro dissolution studies were carried out in a USP type-II apparatus in 0.1N HCl. The formulations were able to within 2-7 minutes and showed buoyancy >12 hrs. The drug-polymer ratio, viscosity grades of Carbopol 934 and gas generating agents were found to influence the release of drug and floating characteristics from the prepared floating drug delivery system of Metronidazole. Kinetically, among the 4 assessed models the release pattern of Metronidazole from the tablets fitted best to Higuchi's and zero order indicated that diffusion is the predominant mechanism controlling the drug release.

a s i t e h o s t e d b y M e d k n o w P u ( w w w . m e d k n o w . c o m ) . Three simple, rapid and accurate visible spectrophotometric methods have been developed using Orange G dye for the quantitative estimation of citalopram hydrobromide, donepezil hydrochloride and rabeprazole sodium from respective tablet formulations. These developed methods are based on formation of chloroform-extractable coloured complex of drug and dye. The extracted coloured complex shows absorption maxima at 476 nm and linearity in the concentration range of 10-50 µ µ µ µ µg/ml for citalopram hydrobromide (method I); at 482 nm and linearity in the concentration range of 5-35 µ µ µ µ µg/ml for donepezil hydrochloride (method II) and at 477.4 nm with linearity in the concentration range of 10-70 µ µ µ µ µg/ml for rabeprazole sodium (method III). The results of analysis for all three developed methods were validated statistically and by recovery studies.

Alginate microspheres for a highly water soluble antidiabetic drug Metformin hydrochloride was prepared by ionic gelation method and investigated for its various physicochemical and release properties. To prevent a rapid drug release from alginate microspheres in simulated gastro-intestinal media, alginate microspheres were blended with polymers, hydroxy propyl methylcellulose, methylcellulose, chitin and chitosan and evaluated as additive polymers for controlling the drug release. Results indicated that quantity of polymer; gelating agent and time of cross-linking affected the shape, size and release characteristics from the prepared dosage forms. Use of polymers to retard the release of drug was effective. Drug release from the microspheres followed swelling and erosion. The selected batches sustained the release of the drug for more than 8 h. and showed drug entrapment efficiency up to 85%. As the polymer concentration in the formulation increased, the drug release generally decreased. HPMC-blended microspheres swelled but withstood the disintegration, showing an ideal linear release profiles. The zero order release was shown by all the formulations except when chitosan was incorporated. In comparison with chitosan-blended microspheres, HPMC-blended and MC blended alginate microspheres can be easily made and used for controlled drug delivery systems due to convenient process and better controlled drug release.

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