A study of the swelling of tablet excipients using video recording

Abstract

A video recording technique was used to study microscopically the swelling characteristics of individual tablet disintegrant particles in water. Feret's diameter, projected area and dimensionless shape factors such as elongation ratio, bulkiness factor and surface factor of various particle profiles were determined. Hydrated particles of cross-linked sodium carboxymethylcellulose (Ac-Di-Sol) and low substituted sodium carboxymethylcellulose (Nymcel ZSB10 and ZSD16) had high Feret's diameter and projected areas. Swelling in their case was due to the hydration of macromolecules. Hydrated microcrystalline cellulose (Avicel PH101) particles had a narrow distribution of both Feret's diameter and projected area. The low degree of swelling in these particles was due to entry of water into particle pores. Fibrous particles of Nymcel ZSB10 retained their elongated shape even after swelling fully. Ac-Di-Sol and Nymcel ZSD16 particles however swelled appreciably along their breadth also and assumed a less elongated profile than when dry. The order for increase in projected area diameter after hydration was Ac-Di-Sol > Nymcel ZSB10 > ZSD16 > Avicel PH101.