Efficacy and safety of a novel naltrexone treatment for dry eye in type 1 diabetes

Background: Dry eye disease (DED) is a prevalent complication of diabetes and presents as reduced tear production and/or increased corneal surface sensitivity often with secondary ocular surface changes. This study examined the safety and efficacy of a proprietary new eye drop formulation for topical treatment of DED. Methods: Type 1 diabetes (T1D) was established in male Sprague-Dawley rats to study the efficacy and safety of the investigational compound that contained 20 μg/ml of naltrexone (NTX). Tear production was measured by the Schirmer's 1 test, and ocular surface sensitivity was measured using an aesthesiometer. Diabetic rats received twice daily applications of a single drop (~ 0.02 ml) of the proprietary formulation (NTX-001) or vehicle onto one eye. For comparison, some diabetic rats received eye drops containing NTX in sterile Vigamox®. Safety was monitored by assessment of ocular histopathology in naïve male rats and naïve male rabbits receiving twice daily treatment of two drops for 30 days. Results: Dry eye in T1D rats was reversed within hours of a single treatment of NTX-001, and over a period of 10 days NTX-001 restored corneal sensitivity and reversed dry eye relative to values measured in diabetic rats receiving vehicle. In comparison to NTX dissolved in Vigamox®, the proprietary NTX-001 was more effective at reversing dry eye. Safety studies in naïve rats and rabbits revealed no visible ocular pathology after 30 days of treatment. Conclusions: An investigational new eye drop containing 20 μg/ml NTX effectively reversed tear film deficits and restored corneal surface sensitivity in diabetic animals without causing toxic side effects.