The role of disintegrants in hard-gelatin capsules

Experiments were designed to investigate the efficacy of various disintegrants on hydrochlorothiazide dissolution from soluble (lactose) and insoluble (dicalcium phosphate) fillers at various lubricant concentrations and compression forces. Capsule fill weights as well as slug hardness appeared to be influenced by the addition of disintegrants. Disintegration times were not always in rank order agreement with dissolution data. Analysis of the dissolution data by 3-way analysis of variance revealed that all the main factors (disintegrant, compression force, lubricant and/or diluent) and their interactions were significant. The presence of interactions limits the conclusions to be drawn; however, an assessment of the averaged effect of each factor separately revealed several important relationships. A compression force effect was evident in most cases at the lower disintegrant concentration, and lower lubricant concentrations or a more soluble filler appeared to require lesser amounts of disintegrant. The magnitude and order of effectiveness of the disintegrants were altered when the filler system was changed from lactose to dicalcium phosphate.