Characterization of supramolecular gels based on β-cyclodextrin and polyethyleneglycol and their potential use for topical drug delivery

Novel gels were prepared by blending p-cyclodextrin and polyethyleneglycol (PEG) in the presence of K2CO3. The objective of this study was thus to characterize the gels using rheology, modulated temperature differential scanning calorimetry (MTDSC), turbidity measurements, and hot stage microscopy, and then investigate the potential use of the gel for topical drug delivery. Two types of supramolecular gels, Gel(L) and Gel(H) were prepared at a low temperature (below 50 degrees C) and at a high temperature (above 70 degrees C), respectively. Both gels were thermoreversible. Upon heating, Gel(L) could turn to Gel(H). Nevertheless, upon cooling, Gels that was more stable than Gel(L) precipitated and Gek could not be reformed. Gel(L) may form through simple complexation of polyethyleneglycol (PEG) with p-cyclodextrin in the presence of K2CO3. However, Gel(H) may form a specific complex or a pseudopolyrotaxane gel. For pharmaceutical application, Gel(L) was investigated instead of Gel(H) because the forming temperature of this gel was close to the human body temperature. The interactions among diclofenac sodium (DS), a model drug, and the components of the gel were examined using FTIR These interactions may include ionic attraction and hydrogen bonds between the carboxylate groups of DS and the hydroxyl groups of PEG or beta-cyclodextrin and probably also the inclusion of the aromatic ring of DS into the cavity of beta-cyclodextrin. Furthermore, the release and permeation of diclofenac from Gel were significantly greater than those from a commercial gel. Therefore, Gek may be useful for the topical delivery of drugs. (C) 2015 Elsevier B.V. All ri ghts reserved.