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Diazepinium perchlorate-promoted acetylation of free as well as partially protected sugars, phenols, thiophenols, thiols, other alcohols and amines is described.

The present study was aimed towards the development of controlled release formulations of Losartan Potassium based on designed to enhance the bioavailability by prolonging its duration in the stomach via the floating dosage forms with controlled release. This study was intended to evaluate the influence of formulation variables like levels of polymer, amount of mannitol concentrations, and coating solution ratios of semi permeable membrane on the drug release from the developed formulations. Thus, there is a strong clinical need and market potential for a dosage form that will deliver Losartan Potassium in a controlled manner to a patient needing this therapy, thereby resulting in a better patient compliance. This study was designed to enhance the bioavailability of drug by prolonging its duration in the stomach via the floating dosage forms with controlled release. Floating matrix tablets of Losartan Potassium were prepared by the direct compression method, using locust bean gum and HPMC K 15M as polymers and Sodium bicarbonate as floating agent. The effect of the nature of polymers was studied by preparing various formulations of tablets. In all these formulations, a constant amount of drug (100 mg) was maintained. The blend was initially characterized for pre-compression and post- compression parameters. Pre-compression characterization was done for angle of repose, bulk density, tapped density, Carr’s index, and Hausner’s ratio. The results of pre-compression characterization were indicated good to excellent flow characteristics. Post-compression characterization includes thickness, hardness, friability, weight variation, drug content, buoyancy lag time, floating time and in-vitro drug release. All the results were satisfactory as per the guideline of pharmacopoeia. The in vitro drug release studies found that formulations LPFT4 showed best sustained release profile in 24 hrs. Among the nine formulations (LPFT1 to LPFT9) prepared formulations LPFT4 was found to be the best formulations in terms of sustained drug release. Drug release kinetics was performed by using various kinetic models such as Zero order, First order, Korsmeyer- Peppas and Higuchi’s equation and followed supercase II transport diffusion kinetic models. Keywords: Oral drug delivery system, Gastroretentive technology, losartan potassium, floating tablet, matrix tablet

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