Research subject: Contact lens-based drug delivery is expected to be more efficient due to sustained release of drug and increased residence time in the tear film. In particular, hydrogel has been applied in contact lenses due to impressive function such as biocompatibility, wettability and optical transparency. Nevertheless, hydrogel lenses suffer from low oxygen permeability. To reduce the shortage of oxygen supply, the silicone-based polymers were used to improve the oxygen permeability. Vitamin E as a diffusion barrier could be introduced into silicone hydrogel contact lenses to extend drug release due to its lipophilic barrier.
Research approach: In this research, poly(3-(methacryloyloxy)propyltris(trimethyl-siloxy) silane-co-2-hydroxyethyl methacrylate) (poly(TRIS-co-HEMA)) copolymers were synthesized in order to evaluate the potential of these copolymers to be used as contact lens materials. The obtained copolymers were characterized using Fourier transform infrared spectroscopy, transmittance analysis, contact angle measurement and water content. The vitamin E was incorporated into copolymer films and the effect of vitamin E loading on extended drug delivery for diclofenac sodium were examined.
Main results: The equilibrium water content (EWC) of the synthesized poly(TRIS-co-HEMA) copolymers were proportional to the hydrophilic PHEMA content. The maximum value of surface hydrophilicity was 56.4°, corresponding to an equilibrium water content of 39%. Poly(TRIS-co-HEMA) films exhibited high transparency in the visible light wave range. Incorporation of vitamin E did not have significant impact on the wettability, EWC and transparency of the copolymer films. The results showed that with vitamin E loading in the copolymer film, the diclofenac release time could be increased to 90 h, which was a 3 fold increase compared to the diclofenac release duration by copolymer film without vitamin E loading. The vitamin E loaded poly(TRIS1-co-HEMA8) copolymer films could be very useful vehicles for extended drug delivery of diclofenac.