New Cyclodextrin Hydrogels Cross-Linked with Diglycidylethers with a High Drug Loading and Controlled Release Ability

Purpose The goal of the study is to develop new hydrogels based on cyclodextrins cross-linked with ethyleneglycol diglycidylether (EGDE) under mild conditions, to be used as carriers of amphiphilic drugs. Also, it aims to characterize the cross-linking and the drug loading and release processes. Methods The cross-linking of hydroxypropyl-β-cyclodextrin (HPβCD) with EGDE, in the absence or presence of hydroxypropylmethylcellulose (HPMC) Methocel? K4M, was optimized applying oscillatory rheometry and Fourier transform infrared. Hydrogels were characterized regarding swelling in water, ability to load diclofenac, and release after different drying treatments. Results Solutions of HPβCD (14.28%), without or with HPMC (0.2–1.0%), provided firm and transparent hydrogels after cross-linking with EGDE (14.28%), in which around two thirds of the OH groups were cross-linked. The incorporation of HPMC progressively reduced the gel time and the swelling degree of hydrogels. HPβCD hydrogels efficiently loaded diclofenac and sustained the release for several hours. The presence of HPMC slowed the release from swollen hydrogels, but promoted it from hydrogels dried before the loading and also before the release. Conclusions HPβCD hydrogels with good mechanical properties and tunable loading and release ability can be obtained by direct cross-linking with EGDE. *The work described in this paper is the subject of patent applications filed by the University of Santiago de Compostela.