TABLETING OF CONTROLLED-RELEASE MULTIPARTICULATES, THE EFFECT OF MILLISPHERE SIZE AND PROTECTIVE OVERCOATING

Controlled release enalapril millispheres of different diameters were prepared and tableted with excipients in a 1:1 ratio on a Carver press . Drug release rate profiles showed that the microporous coaling on th e millispheres was severely damaged during the compression process. Ov ercoating of the microporous coating with hydroxypropyl methylcellulos e E5 (HPMC E5) protects the microporous coating during compression by absorbing and dissipating the compressional forces. This protection be comes more pronounced as the size of the millispheres is reduced. A no vel investigation of individual millisphere strength was conducted to identify the most favorable coating and size combination which would p reserve the controlled release properties of the millispheres. (C) 199 8 Elsevier Science B.V. All rights reserved.