Polyols as filler-binders for disintegrating tablets prepared by direct compaction

Although polyols are frequently used as tablet excipients in lozenges, chewing tablets, and orodisperse tablets, special directly compressible (DC) forms are recommended as filler-binder in common disintegrating tablets.

In this article, DC types of isomalt, lactitol, mannitol, sorbitol and xylitol are evaluated.

Tablets of both lubricated and unlubricated DC polyols and theophylline tablets were compressed at different forces using a compaction simulator or a motorized hydraulic press. Disintegration times (without disks) and dissolution rate were measured according to Ph.Eur.

Compaction profiles show that the DC forms of isomalt, mannitol and sorbitol have sufficient compactibility and a low lubricant sensitivity. The crushing strengths of tablets, prepared from DC lactitol and xylitol, are too low for practical use. Because of their reduced hygroscopicity and smaller capping tendency as compared with DC sorbitol, DC types of isomalt and mannitol seem to be the most convenient filler-binders. Because of their high water solubility, tablets prepared from polyols erode rather than disintegrate. Tablet formulations with theophylline as a test drug and DC isomalt or DC mannitol as filler-binder show that both products have their own limitations: DC mannitol gives more adhesion problems than DC isomalt. On the other hand, the disintegration time and drug dissolution rate for tablets containing DC mannitol is faster than for tablets containing DC isomalt.

Of the DC polyols investigated, both DC isomalt and DC mannitol are the most suitable filler-binders for disintegrating tablets, prepared by direct compaction.