Comparative dissolution study of drug and inert isomalt based core material from layered pellets

• Layered and coated pellets were prepared.
• Diclofenac sodium and isomalt were selected as model drug and as core material.
• Image analysis was applied to determine the swelling behavior of the pellets.
• Simultaneous dissolution of both the drug and isomalt was analyzed.
• Correlation was found between the dissolution profile of the drug and the isomalt.

Layered and coated pellets were formulated to control the release of the diclofenac sodium selected as model drug. A highly water soluble isomalt inert pellet core material was used to osmotically modulate the drug release through the swellable polyvinyl acetate coating layer. Image analysis was applied to determine the shape parameters and the swelling behavior of the pellets. UV-spectroscopy and liquid chromatography with refractive index detection were applied to measure the concentration of the model drug and the core materials. Simultaneous dissolution of both the diclofenac sodium and isomalt was observed. Relationship was found between the dissolution profile of the drug and the core material which linear correlation was independent on the coating level. The latter enables the modulation of drug release beside the permeability control of the swelled coating polymer.