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Pharmaceutical tablet characterized by a showing high volume increase when coming into contact with biological fluids

  • US 5,780,057 A
  • Filed: 02/14/1997
  • Issued: 07/14/1998
  • Est. Priority Date: 02/19/1996
  • Status: Expired due to Term
First Claim
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1. A pharmaceutical tablet wherein the active ingredients are released at a controlled rate selectively in the first portion of the gastrointestinal tract, said tablet having a multi-layer structure and comprising:

  • a) a first layer, which considerably and rapidly swells in the presence of biological aqueous fluids, said swelling resulting in an increase by at least 50% of the total volume of the tablet when coming into contact with the gastric juice, said layer being formed by a compressed granular mixture of biocompatible hydrophilic polymers and at least one highly swellable (superdisintegrating) polymer selected from the group consisting of cross-linked polyvinylpyrrolidone, hydroxypropylcellulose and hydroxypropyl methylcellulose having molecular weight up to 150,000, cross-linked sodium carboxymethylcellulose, carboxymethyl starch, sodium carboxymethyl starch, potassium methacrylate-divinylbenzene copolymer, polyvinyl alcohols, amylose, cross-linked amylose, starch derivatives, microcrystalline cellulose and cellulose derivatives, alpha-, beta-and gamma-cyclodextrin and dextrin derivatives in general, said substances amounting to 1% to 90% of the layer weightb) a second layer, adjacent to the first and containing the active ingredient, made out of biodegradable and biocompatible polymeric materials and other adjuvants whereby the formulation can be formed by compression and the active ingredient may be released within a time interval that may be predetermined by preliminary tests in vitro;

    c) an optional third layer, formed by compression and applied to the second layer, comsprising erodible and/or gellable and/or swellable hydrophilic polymers and, being initially impermeable to the active ingredient, acting as a barrier modulating the release of the active ingredient contained in the adjacent 2nd layer, said third layer optionally being identical with the first layer in composition and functional characteristics.

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