Drug release mechanisms from Kollicoat SR:Eudragit NE coated pellets.

Thin, free films based on Kollicoat SR:Eudragit NE blends were prepared by casting or spraying aqueous dispersions of these polymers, and were thoroughly characterized with respect to their water uptake behavior, water permeability, dry mass loss kinetics, mechanical properties and drug release patterns. A mechanistic mathematical model based on Fick's law of diffusion was used to quantify the experimentally measured release of metoprolol succinate from various types of systems. With increasing Eudragit NE content the films became more hydrophobic, resulting in decreased water permeability as well as water uptake rates and extents.