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 be one of the most omportant factors affecting the dissolution characteristics of compressed tablets containing coated particles. Twenty μm seemed to be 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.
