Mechanism of Action of Starch as a Tablet Disintegrant I: Factors that Affect the Swelling of Starch Grains at 37°

Abstract

A study was initiated to determine if starch grains swell at 37° and what environmental conditions may influence swelling. To determine the extent of swelling which starch undergoes in various media, individual grain dimensions were measured microscopically. Full factorial experiments were conducted, and analyses of variance were calculated to determine whether significant differences in the mean grain sizes could be demonstrated when environmental conditions were changed. Potato, corn, and arnioca starches and moisture content showed significant swelling in distilled water and simulated gastric fluid U.S.P. This was postulated as due to initial size difference of the grains being maintained during the experiment. Variation in pH had very little effect on swelling; however, evidence was obtained to show that the less acid medium produced more swelling than the media of lower pH. Salts did affect swelling, and results indicated that salts of polyvalent cations produced more swelling than the salts of monovalent cations. Analysis of the effect of time on swelling indicated that. any swelling of the starch grains is apparently instantaneous.