Ocular drug targeting by liposomes and their corneal interactions

Topical drug delivery is preferred in the eye to avoid under or over medica tion and undesired side effects of systemic administraion. In order to main tain adequate drug levels in ocular tissues, frequent drug installation is necessary in vision threatening conditions like glaucoma, corneal ulcers du e to microbial infections, etc. Only a part of the installed drug reaches t he aqueous humor and the rest of it is drained by the nasolacrimal duct. Po sitively charged liposomes have been found to enhance the penetration of dr ugs into the cornea. The present study was conducted to Visualize the inter action of liposomes with the cornea. Briefly, positively charged liposomes entrapped with Carboxyfluorescein (CF), Propidium iodide (PI), Horseradish peroxidase (HRP), Biotin, Hydroxy benzimide (Hoechst No: 33258), and Ethoxy benzimide (Hoechst No: 33342) were prepared by sonication. Their size and shape were analysed by laser dynamic light spectra and electron microscopy, respectively. The liposome encapsulated and free materials in buffer were instilled, in a Volume of 20 mu l, into eyes of anesthetized albino rats. A fter 30 min and Ih, the eyes were enucleated and quickly processed for cryo sections of 3-5 mu m thickness. The interaction of liposome entrapped propi dium iodide and HRP was visualized on the outer epithelium of the cornea af ter specific processing.