Mucoadhesive niosomal in situ gel for ocular tissue targeting: in vitro and in vivo evaluation of lomefloxacin hydrochloride

Eradication of ophthalmic infections depends on increasing transcorneal permeation and localizing antibiotics at ocular surface. This study aimed at formulating lomefloxacin HCl (LF) in the form of niosomes and evaluating the in vivo performance of best formula in rabbits' eyes. Vesicles were developed by mixing three surfactants at three molar ratios of 1: 1, 1: 2 and 1: 3 of surfactant to cholesterol. Size, zeta potential, release percentage, transcorneal permeation parameters, stability studies, cytotoxicity and antibacterial activity of niosomes were determined. Niosomes showed encapsulation efficiency of more than 78%, particle size below 500nm and zeta potential below -43.6. The produced vesicles showed significantly higher amounts of drug permeated across cornea (166%) compared to LF solution. The in vivo study showed 2-5 folds increase in drug concentration in ocular fluids and tissues following administration of niosomes compared to marketed formula (from 3.75 to 10.31 mcg/mL in the cornea). Microbiological studies showed 35 folds increase in the antibacterial activity of LF niosomes compared to free drug; where MBC decreased from 31.25 mcg/mL in case of LF solution to 0.97 mcg/mL for niosomal gel. The formulated niosomes enhanced the ocular bioavailability of LF through increasing transcorneal permeation and localizing drug at site of action.