Croscarmellose Sodium

Croscarmellose sodium is a cross-linked polymer of carboxymethylcellulose sodium, engineered to swell rapidly on contact with water while remaining insoluble. This controlled insolubility is the key to its function as a super-disintegrant: the polymer absorbs water, swells to many times its dry volume and generates the internal pressure that breaks the tablet matrix apart within seconds.

Manufactured by cross-linking sodium carboxymethylcellulose with subsequent acid washing and drying, the resulting fibrous white powder retains a high degree of substitution (0.60–0.85) that drives the swelling mechanism. Unlike sodium starch glycolate, croscarmellose sodium does not form a viscous gel layer at typical use levels, which avoids any retardation of drug release.

It is effective at low concentrations — typically 2–5 % w/w — and can be incorporated both intragranularly and extragranularly for a dual disintegration effect. This versatility, combined with compatibility with most APIs, makes it one of the three super-disintegrants listed in every major pharmacopoeia (IP, BP/Ph. Eur., USP-NF).

Applications extend beyond standard tablets to orally disintegrating tablets (ODTs), capsule fills, granules and co-processed excipient systems. In each case, croscarmellose sodium ensures that the dosage form breaks down quickly enough for the API to dissolve and be absorbed within the therapeutic window.