Evaluation of a cyclosporine A ophthalmic ointment in an experimental mouse model of dry eye

Purpose Dry eye syndrome is a common disease with multifactorial causes. Symptoms typically include irritation, dryness, burning and decreased or fluctuating vision. Anti-inflammatory drugs are widely used for the treatment of the inflammation produced by the disease with corticoid or cyclosporine A (CsA). Restasis® (Allergan), a CsA emulsion, was approved by the FDA but is not available in Europe. Here we propose to show the action of Optimmune® (MSD Animal Health) a marketed veterinary ophthalmic ointment that contains CsA in an experimental mouse model of dry eye induced by scopolamine, a tropane alkaloid drug with muscarinic antagonist effects. Methods Animals were divided in three groups of ten pigmented mice: Two groups were exposed to desiccating conditions (relative humidity <25%, air-flow 15 L/min, temperature 20-22°C) with transdermal scopolamine administration (0.5 mg/72 h) for 14 days. Animals were treated topically three times a day with 0.2% CsA ointment or vehicle. Controls were saline-treated animals placed in a normal environment. Tear production was measured with the phenol red thread test, corneal defects were examined by slit-lamp observation using blue light after 0.5% fluorescein eye drop. These examinations were performed in both eyes before exposure and on days 3, 7 and 14. A histological study was performed at the end of the study. Results Cyclosporine A eye ointment appeared to show efficacy in this model. Conclusions Cyclosporine A eye ointment significantly reduced clinical signs of dry eye by decreasing corneal defect more than cyclosporine A ophthalmic emulsion (internal studies).