Structure and dry binding activity of different polymers, including Kollidon VA 64

The dry binding activity of copolyvidone (Kollidon VA 64), povidone (Kollidon 30), microcrystalline cellulose (Avicel PH-101), hydroxypropylmethylcellulose (HPMC) 2910 (Pharmacoat 606), and maltodextrin (Maldex 18) was investigated using a variety of formulations and methods. The effect of the dry binders in direct tableting and compaction was studied using a dicalcium phosphate formulation (water-insoluble ingredients) and a vitamin C formulation (water-soluble ingredients) applying three compression forces. The binder content was varied between 5% and 15% in both formulations, and the tablet properties were determined. All the tablets showed an improvement in mechanical properties (hardness, friability) with increasing dry binder concentration, with Kollidon VA 64 showing by far the greatest binding efficacy. A significant influence (prolongation) on drug release was observed only with HPMC 2910. The drying binding properties were analyzed for correlations with various powder and material properties. Especially, particle size, surface/surface structure, and plasticity were found to influence binding activity. The ideal dry binder should have small particles, high plasticity, and a large surface area.