Cyclosporin nanosphere formulation for ophthalmic administration

Cyclosporin A (CsA) is a widely used anti-inflammatory agent for the management of dry eye disease, and is available commercially as ophthalmic emulsion formulation (RESTASIS®). For increasing efficacy, and for reducing local toxicity including irritation to eyes, CsA nanosphere (CsA-NS) formulation was prepared and evaluated, in this work. CsA-NS formulation was prepared in a pre-concentrate form, which is a homogeneous solution of a CsA in a mixture of surfactants, lipids and solvents and provides nanosphere dispersion when added to aqueous medium. CsA-NS formulation was characterized and adjusted for particle size, pH, and osmolarity, suitable for ophthalmic administration. Thereafter, CsA-NS formulation was evaluated for parameters like irritation to eyes and penetrability of CsA in the rabbit eyes. Results obtained demonstrated that proposed CsA-NS formulation causes less irritation in rabbit eyes, with nearly same CsA penetration in the rabbit eyes in comparison to marketed emulsion formulation.