Characterization of enteric-coated tablets and pellets by two in vitro dissolution methods and by scanning electron...

The in vitro dissolution rates of enteric-coated pellets and tablets containing dexchlorpheniramine maleate (DCPM) were obtained using the USP XXI paddle and a flow-through method. Pellets were produced by extrusion and spheronization. Tablets were produced by direct compaction, and by wet granulation. The products were coated with different amounts of Eudragit L30D using fluid-bed technology. Onset of release, determined by fitting of the Weibull function, was the only factor found to be affected by the amount of coating of the tablets. For pellets, both onset of release and dissolution rate showed significant differences. Scanning electron microscopy was used to study the effect of different dissolution media on the coating. Acidic medium was found to alter the coating surface, but the coating did not rupture during the time used in this study.