摘要：

A sustained-release pharmaceutical composition which comprises microparticles comprising an active principle, said microparticles being coated with a coating mixture comprising ethyl cellulose and an acrylic resin which is a polymerizate of acrylic and methacrylic ester, having a molecular weight of at least 100,000 and comprising units of formula: ##STR1## wherein: R 1 is hydrogen or methyl, R 2 is methyl or ethyl, R 3 is methyl; and R 4 is --CH 2 --CH 2 N(CH 3 ) 3 Cl the resin containing 5% of trimethylammonium methacrylate chloride units by weight.

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