Disintegration Mechanisms of Tablets Containing Starches. Hypothesis About the Particle-Particle Repulsive Force

Abstract

The disintegration of a tablet immersed in a liquid appears to be essentially a mechanical phenomenon: penetration of liquid then destruction of compressed structure For a number of authors, the starch granule swelling is the mechanical force which destroys the tablet. Indeed, a study on a series of experimental carboxymethylstraches indicates that those that do not swell, show the same disintegration time to those that do swell. We can also notice that the carboxymethylstarches wich swell much less in a gastric medium, produce even shorter disintegration times in this medium. The destruction of the cohesion forces between the constitutive elements of the tablet under the action of water may be ascribed to the creation of a repulsive force when the elements of the tablet enter into contact with water, or to a simple annihilation of the hydrogen bonds or of the capillary cohesion forces. The hydrophilic nature of starch seems to be determinant: water penetrates into the tablet owing to hydrophilic porosity under the action of an important hydrostatic pressure.