Mechanism of Action of Starch as a Tablet Disintegrant III: Factors Affecting Starch Grain Damage and Their Effect on Swelling of Starch Grains and Disintegration of Tablets at 37°

Abstract

A study was undertaken to determine the effect of the tableting procedure on starch grain swelling and tablet disintegration. The swelling of damaged starch grains in simulated gastric fluid USP is demonstrated. Submersion of starch samples that had been ball milled from 10 to 48hr. produced increases in grain diameters of 40 to 80 percent. Damage to the grains resulting from compression of pure cornstarch is shown to be insignificant. The effect of compressional force and hardness of tablet ingredients was examined and in each formulation the starch grain damage increased with compressional force. There was no correlation between degree of starch grain damage and hardness of the tablet ingredients. It appeared that the crystalline form of the ingredient may have exerted a greater influence on starch damage than the hardness. There was no correlation between starch damage and stress produced by elastic recovery of the tablet. Contrary to what might be expected, there was an inverse relation between the amount of stress and the degree of starch grain damage for all of the formulations except aspirin. There was no evident relationship demonstrated between disintegration time and starch grain damage. Outside of compressional force, the inherent effect of the tablet ingredient was the only factor that appeared to affect disintegration. The long-accepted swelling mechanism of starch as a tablet disintegrant was not demonstrated in this study. The results of the investigation revealed no measurable correlations between starch grain damage and disintegration or between starch swelling and compressional force.