Disintegrants are required to break up capsules, tablets and granules into primary powder particles in order to increase the surface area of the drug exposed to the gastrointestinal fluids. A tablet that fails to disintegrate or disintegrates slowly may result in incomplete absorption or a delay in the onset of action of the drug.
The compaction force used in tablet manufacture can affect disintegration: in general, the higher the force the slower the disintegration time. Even small changes in formulation may result in significant effects on dissolution and bioavailability. A classic example is that of tolbutamide, where two formulations, the commercial product and the same formulation but with half the amount of disintegrant, were administered to healthy volunteers. Both tablets disintegrated in vitro within 10 minutes meeting pharmacopoeial specifications, but the commercial tablet had a significantly greater bioavailability and hypoglycaemic response. [Aulton’s Pharmaceutics, 2nd ed]