Spanlastics--a novel nanovesicular carrier system for ocular delivery.

The work describes usefulness of a novel, surfactants based elastic vesicular drug carrier system (spanlastics), for targeting topically applied drug(s) to the posterior segment of the eye. The system constituted span 60 and a edge activator (tween 80). Ketoconazole, a lipophilic drug with a large molecular weight of 531.44 Da and a limiting solubility of 0.04 mg/ml is expected to show a poor transport across the cornea; hence no ocular formulations are available. Developed spanlastics were of nanosize and elastic in nature. They showed 2 times better corneal permeation (p ≤ 0.001) in comparison to correspondingly prepared niosomal formulation. The system was tested for stability for 2 months under refrigerated conditions. It was found to be safe in terms of genotoxicity (Ames test), cytotoxicity (MTT assay; Normal human gingival fibroblast), acute dermal/eye irritation/corrosion and chronic eye irritation/corrosion tests (OECD guidelines). Safety was an important issue considering that the system is novel (Indian Patent Application 2390/DEL/2008; 1447/DEL/2010) and is totally surfactant based (spans plus edge activators). Fluorescent vesicles labeled with 6-carboxyfluorescein when applied topically to the rabbit eye were observed intact in vitreous and the internal eye tissues 2h post application. Results confirm that spanlastics can be used to deliver drugs to the posterior segment of the eye.