Studies on Powdered Preparations. XX. Disintegration of the Aspirin Tablets containing Starches as Disintegrating Agent

Abstract

87 groups of tablets were made using 3 sieved fractions of aspirin and potato or corn starch varying formulation and compressional force. Disintegration of the tablet was investigated in detail by the thermal analysis reported previously. The relation between porous structure of tablet and disintegration was studied and the following conclusions were drawn from the results obtained. 1. The rate-determining step of the disintegration was the penetration of water into the porous structure of a tablet. 2. It was confirmed that starch can develop the capillary structure in aspirin tablet. This effect was observed when aspirin particles larger than starch grains were mixed with starch. The effect seemed to be larger at corn starch than potato starch. 3. There should be the critical amount of starch necessary for the disintegration depending upon the particle size or the specific surface area of ingredients. The smaller the particle size of aspirin, the more amount of starch was required for the tablet disintegration. The tablet of the smallest aspirin (11.9 μ in mean particle size) did not disintegrate by the addition of 20% of starch. 4. In the case of the tablets that disintegrated very rapidly and completely, the wall of the capillaries in the tablets was considered as starch. This may be the reason why the tablet with potato starch disintegraties more rapidly than with corn starch. 5. The model proposed for disintegration well explained why the tablet made from the medium aspirin particle (294 μ in mean volume-surface particle diameter) disintegrated more rapidly than that containing the largest aspirin (953 μ).