Gastric floating tablet was also known as gastric stranded film, floating administrat system or water dynamic equilibrium system. Davis1 proposed this new preparation concept the density was less than 1 and could drift on the fluid surface in order to overcome the seldom gas and nausea phenomenon when medication in 1968. Drug release of gastric floating in vitro could be described by variety dynamics formula, the most of which accorded to Higuchi formula and Korsemeyer Peppas (Mt/M~∞= ktn) empirical formula. At present the drug agents could be classified of floating gastric stranded system, bioadhesive floating gastric stranded system, gastric stranded system affected by floating and bioadhesive, high density gastric stranded system and obstructive stomach stranded system according to in the size, proportion and mechanism of agents in vivo. For floating time, the macromolecular material had a faster hydration speed than the small molecular material. For floating stranded time, the barriers viscosity of gel made by expansion of macromolecular materials was large and the dissolution was slow that was better to prolong the strand time and enhance the floating property. Prescription of aspirin gastric floating tablets(100 tablets dosage, g): aspirin 30, HPMC 12, CMC2Na 5, CaCO3 2, MgCO3 1.5, mannitol 1, magnesium stearate 0.5.
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