Formulation and In Vitro Evaluation of Floating Tablets of Losartan PotassiumY.S. Tanwar*, M. Jamini, and B. Srivastava
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Drugs that have narrow absorption window in the gastrointestinal tract (GIT) will have poor absorption. For these drugs, gastroretentive drug delivery systems offer the advantage in prolonging the gastric emptying time. Losartan potassium is prescribed to treat hypertension. Intragastric buoyant sustained-release tablets were prepared in this investigation by wet granulation method using hydrophilic polymer (Methocel), effervescent substance (sodium bicarbonate, citric acid) and drug (losartan potassium). Floating tablets of losartan potassium were evaluated for physico-chemical characteristics, floating lag time, total duration of floating and in vitro drug release. The addition of gel forming polymer Methocel K15, Methocel K100 with gas generating agent sodium bicarbonate was essential to achieve in vitro buoyancy. Stable and persistent buoyancy was achieved by trapping the gas in the gel formed by the hydration of high-viscosity Methocel. The drug release mechanism from floating tablets was found to be non-Fickian (i.e. anomalous diffusion) according to Korsmeyer-Peppas equation. This study showed that there was potential for intragastric floating tablets to remain in the stomach for a longer period of time with sustained drug release.
Keyword:
Gastroretentive drug delivery system, Floating tablets, Buoyancy, Losartan potassium.
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