Optimization and formulation of cyclosporine-loaded nanostructured lipid carriers (NLCs) for the management of dry eye syndrome by using centre composite design approaches.

The quality of life of patients with Dry Eye Syndrome (DES), a multifactorial ocular surface disease, is significantly affected by symptoms such as increased inflammation, ocular pain, and tear-film instability. Among the therapeutic agents used, Cyclosporine A (CsA) plays a critical role in modulating immune-mediated inflammation associated with DES. Conventional CsA formulations, like oil-in-water emulsions (e.g., Restasis®), fail to perform as well in the healthcare setting because they fail to disintegrate well in water, fail to distribute to the eye well, take a long time to work, and can irritate patients. This study focuses on the optimization, development, and assessment of a nanostructured lipid carrier (NLC)-based delivery system for Cyclosporine A, designed to address the limitations of traditional therapies and enhance treatment outcomes in dry eye syndrome (DES). CsA-loaded NLCs were further optimized using the Design Expert 12 Vision Response Surface methodology with a Central Composite Design and were formulated via hot homogenization. Their distinctive features included significant physicochemical properties. Factors such as particle size, zeta potential, polydispersity index (PDI), encapsulation efficiency, drug loading, and transmission electron microscopy (TEM) are included. Drug release was studied in vitro using simulated tear fluid, and permeation was assessed using Franz diffusion cells. The optimized NLCs demonstrated a particle size of 196.9 ± 3.4 nm, a PDI of 0.406 ± 2.1, and a Zeta potential of -24.1 ± 1.8 mV. The entrapment efficiency was measured at 85.6 ± 2.8%, indicating a high level of effectiveness. The particle size was measured under 200 nm, as indicated by TEM analysis. At 12 h, the cumulative drug permeation from the CsA-NLCs reached 47.5 ± 1.5 µg/cm