Purpose
Dry eye is a steroid responsive ocular surface inflammatory disease. Therapeutic efficacy of dexamethasone treatment with a controlled release nanowafer (Dex-NW) or drops was compared in a murine desiccating stress model of dry eye.
Methods
Carboxymethyl cellulose (CMC) nanowafers and phospho dexamethasone loaded CMC nanowafers (Dex-NW) were fabricated by hydrogel template strategy. The in vivo efficacy of the Dex-NW was evaluated in the experimental dry eye induced mouse model by measuring corneal barrier function to 70kDa Oregon green dextran (OGD) and expression of inflammatory genes by RT-PCR.
Results
The nanowafer drug delivery system was designed for sustained controlled delivery of dexamethasone to ocular surface tissues (cornea/conjunctiva) in a controlled fashion and in vivo efficacy was demonstrated in a 5-day experimental dry eye induced mouse model. Corneal epithelial barrier disruption was measured by intensity of staining with fluorescent Oregon green conjugated dextran (OGD). Dex-NW placed on the bulbar conjunctiva on days 1 and 3 was equally effective as dexamethasone drops instilled twice a day eye for five days (Figure 1). RT-PCR analysis revealed that the down regulation of drug target genes IL-1α, IL-1β, TNF-α, IFN-δ, and MMP-3, and MMP-9 by Dex-NW treatment was comparable to twice a day topically administrated dexamethasone eye drop formulation (Figure 2). In both these studies, the dexamethasone delivered by the eye drop treatment was 20 µg compared to 5 µg of the drug delivered by the nanowafer during the same treatment period.
Conclusions
The Dex-NW was equally effective in suppressing dry eye induced corneal inflammation as conventional dexamethasone eye drops, even at a 4-fold lower drug concentration and alternate day dosing frequency.