Diltiazem Release from Eudragit NE40 Coated Pellets and Effects of Thermal Treatment

A film coat for diltiazem pellets was applied with aqueous dispersion of Eudragit NE40 using bottom spray Fluidized-bed coater. The effects of thermal treatment, dissolution media and ionic strength of media on drug release from the pellets were evaluated. Coated pellets were treated at 37°C, 40°C, 50°C and 6Q°C for 24 hours. Thermally treated pellets showed slight reduction in the release rales at 50°C and 60°C compared to initial release profile at 37°C. Curing or thermal treatment of the coat at an appropriate temperature and length of time was found essential to achieve complete coalescence of the polymer particles such that the rate of drug release was stable during prolonged storage. Diltiazem release was fairly independent of pH and the ionic strength of the dissolution media. However, the release rates were slightly decreased with increasing molar concentrations of sodium chloride in the buffer media.