Controlled release of Ibuprofen from dealuminated faujasites

Four dealuminated faujasite samples have been employed as matrices for Ibuprofen adsorption and in vitro drug delivery with the aim of adapting the pore size to the size of the drug molecule and to study the influence of Al content upon the drug delivery. Ca. 15 wt% of Ibuprofen is adsorbed in the zeolite cavities. FTIR shows that the zeolite hydroxyl groups interact with Ibuprofen and, in addition, carboxylate species bonded to extraframework Al species are detected in the most dealuminated samples. Two stages are observed in the Ibuprofen delivery. In the first hours, the release is governed by a diffusion process, showing a similar delivery rate independently of the Al content. However, after this stage, the Al content is determinant in drug delivery, being the release faster when the framework Si/Al ratio increases up to 22, and then decreases for Si/Al=62. The behaviour of the highly dealuminated material is probably due to the predominance of Van der Waals interaction between the drug and the siliceous zeolite framework.