In-vitro and in-vivo evaluation of enteric-coated starch-based pellets prepared via extrusion/spheronisation

Pellet cores containing modified starch (high-amylose, crystalline and resistant starch) as the main excipient were enteric-coated with an Eudragit ® L30 D-55 based dispersion. The polymer weight gain was from 15% to 30% (w/w). Pellet cores were prepared using piroxicam (2.5% w/w, poor water solubility) and anhydrous theophylline (2.5% and 25% w/w, coarse and micronised powder, medium water solubility) as model drugs. Next to the water solubility, particle size and concentration of the model drugs, the influence of sorbitol (0% and 10%, w/w) and drying method (oven and fluid-bed) on pellet yield, size (Feret mean diameter), sphericity (aspect ratio, AR and two-dimensional shape factor, e R), friability, surface morphology and drug release were evaluated. Binder (HPMC) and granulation liquid (water) concentration were optimised to obtain maximum yield (size fraction between 900 and 1400 μm) and acceptable sphericity (AR < 1.2). Pellet friability was