RELEASE OF INDOMETHACIN FROM TABLETTED ETHYLCELLULOSE MICROCAPSULES

Indomethacin was microencapsulated in a coacervation process using eth ylcellulose as a wall material and polyisobutylene as a coacervation i nducing agent. Micronized sodium chloride was added as a pore former i nto the microcapsule wall. Microcapsules were tabletted with plastical ly deforming microcrystalline cellulose and fragmenting dicalcium phos phate as well as with their binary mixture. The effect of compression pressure on drug release was evaluated. The release of indomethacin wa s also studied after effective disintegration of the tablets by crossl inked sodium carboxymethylcellulose. Release of indomethacin from plai n microcapsules accelerated markedly when sodium chloride was added in the microcapsule wall. All the tablets without disintegrant stayed ne arly intact during the dissolution test. The tablets of microcapsules were composed of a porous ethylcellulose matrix in which the microcaps ules were separated from each other by easily wettable tablet adjuvant s. The drug release accelerated from the tablets due to the mechanical destruction of microcapsule wall, which was more clearly seen after d isintegration of the tablets to the multiple microcapsule units. The r upture of microcapsule films was most extensive with the tablets conta ining fragmenting dicalcium phosphate as a filler. The addition of sod ium chloride in the microcapsule wall seemed to make the polymer film firmer thus reducing the destructive effect of tablet adjuvants.