Lipid Nanocarrier: an Efficient Approach Towards Ocular Delivery of Hydrophilic Drug (Valacyclovir)

This research focuses on the fabrication and evaluation of solid lipid nanoparticles (SLNs) for improved ocular delivery of valacyclovir (VAC). Stearic acid and tristearin were selected as the lipid carrier while Poloxamer 188 and sodium taurocholate were used as surfactant and co-surfactant, respectively. The physiochemical properties of the optimized batch (SLN-6) fulfil the prerequisites needed for an ideal ocular formulation like submicron size (202.5 ± 2.56 nm), narrow PDI (0.252 ± 0.06), high zeta potential (-34.4 ± 3.04 mV) and good entrapment efficiency (58.82 ± 2.45%). The in vitro release study of SLN-6 exhibited a sustained release profile (>60% in 12 h). The ex vivo studies performed on excised cornea exhibited enhanced drug permeation of SLNs (22.17 ± 1.41 μg/cm² h) in comparison to the drug solution (3.78 ± 1.34 μg/cm² h). Apart, the corneal hydration studies, histopathology and Hen's Egg Test Chorio Allantoic Membrane (HETCAM) assay, confirmed the non-irritancy of SLNs. The in vivo study confirmed improved ocular bioavailability of VAC from SLN-6 (AUC_0-12: 856.47 ± 7.86 μg h/mL) in contrast to the drug solution (AUC_0-12: 470.75 ± 8.91 μg h/mL). Hence, the overall studies suggested the potential of SLNs in efficient ocular delivery of a hydrophilic molecule like VAC.