Compressed tablets for disintegration in the colon comprising an active ingredient containing nucleus coated with a first layer containing microcrystalline cellulose which is coated with an enteric organic polymer coating

Claim 1

A compressed tablet for oral administration and disintegration in the colon which consists essentially of: (a) a microcrystalline cellulose-free compressed center piece containing an active agent; (b) a first coating layer amounting to between about 0.5% and about 10% by weight of that of the center, coating the compressed center piece and consisting essentially of a mixture of a pharmaceutically acceptable lower alkyl ether of a cellulose film-forming organic polymer material which is not deteriorated by a neutral or alkaline aqueous medium, and from about 30% to about 80% by weight of the first coating layer of microcrystalline cellulose; and (c) a second coating layer amounting to between about 2% to about 10% by weight of the center, coating the first coating layer and consisting essentially of a microcrystalline cellulose-free pharmaceutically acceptable enteric organic polymer coating material selected from the group consisting of cellulose acetylphthalate, hydroxypropylmethylcellulose phthalate, benzophenyl salicylate, cellulose acetosuccinate, copolymers of styrene and of maleic acid, formylated gelatin, salol, keratin, stearic acid, myristic acid, gluten, acrylic and methacrylic resins, and copolymers of maleic acid and phthalic acid derivatives; each of said coating layers containing a plasticizer selected from the group consisting of diethylphthalate, dibutylphthalate, propylene glycol, castor oil and mixtures thereof.