Pectin/chitosan/Eudragit RS mixed-film coating for bimodal drug delivery from theophylline pellets: preparation and evaluation.

Pellets containing theophylline as a model drug and microcrystalline cellulose, in a ratio of 6:4, were prepared by the extrusion-spheronization method. The pellets were coated with Eudragit RS aqueous dispersions, containing various amounts of pectin-chitosan complex and different coating mass gains, using a fluidized-bed apparatus. Twelve formulations were developed, which differed in two factors: coating mass gain (10, 15 and 20%, m/m) and the amount of pectin-chitosan complex (5, 10, 15 and 20%, m/m).