Effect of molecular structure variation on the disintegrant action of sodium starch glycolate

The effect of variation in the degree of cross-linkage and extent of carboxymethylation on the disintegration and dissolution properties of sodium starch glycolate has been examined. Samples of sodium starch glycolate were evaluated for particle size distributions and bulk and tapped densities. The bulk powders were also tested for sedimentation volumes, water uptake, and bulk swelling. Direct compression formulations containing aspirin and hydrochlorothiazide and varying concentrations of the modified starches were tableted on a rotary tablet press and evaluated for weight variation, hardness, disintegration, and dissolution. The results indicate that relatively small changes in molecular structure can cause substantial modification of disintegrant properties and suggest that the specifications for one commercially available sodium starch glycolate are within optimal specifications for both cross-linkage and degree of substitution.