Towards elucidation of the drug release mechanism from compressed hydrophilic matrices made of cellulose ethers. III. Critical use of thermodynamic parameters of activation for modeling the water penetration and drug release processes

Arrhenius plots of caffeine release (a) and water uptake (b) from HMPC 2910 compressed matrices. The low apparent activation energy values can be assigned to the exothermic dissolution of water in the initially dry HPMC and to the dimensional change of the hydrophilic system during the drug release and swelling processes.134