Cyclodextrin-containing hydrogels for contact lenses as a platform for drug incorporation and release.

Poly(2-hydroxyethyl methacrylate) hydrogels containing beta-cyclodextrin (pHEMA/beta-CD) have been investigated as a platform for sustained release of ophthalmic drugs. First of all, pHEMA/beta-CD hydrogel membranes and contact lenses were prepared by photopolymerization of HEMA, mono-methacrylated beta-CD (mono-MA-beta-CD) and trimethylolpropane trimethacrylate using a cast molding process. The hydrogels were characterized by Fourier transform infrared spectroscopy, equilibrium swelling ratio (ESR) and tensile tester. The results showed that the incorporation of beta-CD in the hydrogels increased the ESR and tensile strength. Then, puerarin was used as a model to evaluate drug loading and in vitro and in vivo release behavior of the pHEMA/beta-CD hydrogels. It was revealed that puerarin loading and in vitro release rate were dependent on beta-CD content in the pHEMA/beta-CD hydrogels. In rabbit eyes the pHEMA/beta-CD hydrogel contact lenses exhibited longer mean residence times (MRT(F)) of puerarin in tear fluid than that of pHEMA contact lenses and 1% puerarin eye drops. The puerarin concentration in the aqueous humor of rabbit reached a maximum of 0.81microg ml(-1) after wearing the pHEMA/beta-CD contact lens, which had been presoaked in 0.802mg ml(-1) puerarin solution for 4.81h. Also, the pHEMA/beta-CD contact lenses had a higher drug bioavailability in aqueous humor than puerarin eye drops. The data demonstrate that pHEMA/beta-CD hydrogel contact lenses can effectively deliver puerarin through the cornea.