Application of Box–Behnken design for preparation of levofloxacin-loaded stearic acid solid lipid nanoparticles for ocular delivery: Optimization, in vitro release, ocular tolerance, and antibacterial activity

Abstract

The aim ofthe present study was to develop and optimize levofloxacin loaded solid lipid nanoparticles for

the treatment of conjunctivitis. Box–Behnken experimental design was applied for optimization of solid

lipid nanoparticles. The independent variables were stearic acid as lipid (X1), Tween 80 as surfactant (X2)

and sodium deoxycholate as co-surfactant (X3) while particle size (Y1) and entrapment efficiency (Y2)

were the dependent variables. Further in vitro release and antibacterial activity in vitro were also per- formed. The optimized formulation oflevofloxacin provides particle size of 237.82 nm and showed 78.71%

entrapment efficiency and achieved flux 0.2493 g/cm2/h across excised goat cornea. In vitro release

study showed prolonged drug release from the optimized formulation following Korsmeyer–Peppas

model. Antimicrobial study revealed that the developed formulation possesses antibacterial activity

against Staphylococcus aureus, and Escherichia coli equivalent to marketed eye drops. HET-CAM test

demonstrated that optimized formulation was found to be non-irritant and safe for topical ophthalmic

use. Our results concluded that solid lipid nanoparticles are an efficient carrier for ocular delivery of

levofloxacin and other drugs.