| 摘要 |
<p>A coating or matrix material for medicaments, comprising a copolymer of (meth)acrylic acid and alkyl or hydroxyalkyl (meth)acrylate, will have the property of being resistent to gastric juice and dissolving or disintegrating only in the colon if the ratio of free carboxy groups to esterified carboxy groups in the copolymer is between 1:4.5 and 1:3 (the limiting values excluded). Such copolymers may be prepared either by direct copolymerisation of monomers in such proportions that a copolymer having the specified ratio is obtained, or else by starting with a copolymer having a ratio between 1:1 and 1:3 and partially esterifying the free carboxy groups therein to reach the specified ratio.</p> |
