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 2 h post application. Results confirm that spanlastics can be used to deliver drugs to the posterior segment of the eye. (C) 2011 Elsevier B.V. All rights reserved.