Tableting of coated particles. II. Influence of particle size of pharmaceutical additives on protection of coating membrane from mechanical damage during compression process

Abstract

To compress coated particles into tablets without mechanical damage to the coating membrane during compression, the effect of the particle size of various pharmaceutical additives was investigated by comparing the dissolution rate and the membrane integrity of ethylcellulose coated theophylline powder. Results showed that smaller additive particle size was superior in protecting the membrane from damage, and thus additive particle size might he one of the most important factorS affecting the dissolution characteristics of compressed tablets containing coated particles. Twenty μm seemed to he the critical particle size for each kind of additive to obtain good protective effect. Up to this size, all additives played the role of cushioning and the coating membrane was almost perfectly protected from potential damage by the compression force.