PVA Hydrogels Containing β-Cyclodextrin for Enhanced Loading and Sustained Release of Ocular Therapeutics

The purpose of this work is to develop poly(vinyl alcohol) (PVA) hydrogels incorporating large amounts of beta-cyclodextrin (beta-CD) in order to improve ocular drug loading and to sustain drug release. First, the mono-methacrylated-beta-CD monomer (MA-beta-CD) and the methacrylated-PVA macromer (PVAMA), with a substitution degree of 7%, are synthesized and characterized. Then, the poly(methacrylated-PVA-co-mono-methacrylated-beta-cyclodextrin) (pPVA-beta-CD) hydrogels are prepared by UV-induced polymerization of MA-beta-CD and PVAMA. The highest amount of beta-CD incorporated into the hydrogels is 30 wt%. The hydrogels are further characterized by transmittance, FT-IR, equilibrium swelling ratio (ESR), tensile tests and protein deposition. The results show that pPVA-beta-CD hydrogels possess good transmittance, while the incorporation of beta-CD in the hydrogels improves the tensile strength and decreases the ESR and protein deposition. Finally, puerarin and acetazolamide are used as models to evaluate the drug loading and in vitro release behavior of the pPVA-beta-CD hydrogels. The results indicate that the amount of drug loaded into the pPVA-beta-CD hydrogels progressively increases, while the release rate decreases with increasing beta-CD content. In particular, incorporation of beta-CD efficiently decreases the initial burst release of acetazolamide, while the release, which is almost linear, is sustained for 15 days. The pPVA-beta-CD hydrogels have potential applications as biomedical devices for sustained release of ocular drugs.