Extended release of ketotifen from silica shell nanoparticle-laden hydrogel contact lenses: in vitro and in vivo evaluation.

Ketotifen an anti-allergic drug delivered via eye drops has major limitations, including poor ocular bioavailability and poor patient compliance. The objective of the research work was to fabricate ketotifen loaded microemulsion laden hydrogels and silica shell nanoparticle-laden (prepared from microemulsion using octyltrimethoxysilane) hydrogels to achieve extended ocular drug delivery. The porous silica shell membrane was synthesized at the liquid interface of microemulsion, which facilitates the prolongation of drug release duration from hydrogels. Drug encapsulated microemulsion and silica shell nanoparticles were dispersed separately in pre-monomer mixture, and fabricated to hydrogel. For comparison, hydrogel with direct drug entrapment was also fabricated. Significant loss in transmittance and physical properties was observed in hydrogels with direct drug entrapment. While, microemulsion and silica shell nanoparticle-laden hydrogels did not show significant effect on transmittance and physical properties. The in vitro drug release data showed extended release of ketotifen from hydrogels in following order: direct loading<microemulsion<silica shell nanoparticles. The results of cytotoxicity and animal study confirmed the safety of hydrogels. The in vivo pharmacokinetic study showed extended ketotifen release for more than 10 days. The results demonstrated the translational potential of silica shell nanoparticles for extended drug delivery without compromising the critical lens properties.