Drugs may also be administered to the eye for local effects on the eye.198 An example of the use of proteins for local effects on the eye is the family of growth factors, which has several applications in the ocular area. There are about 35 or more such growth factors; a prominent one is the epidermal growth factor (EGF). As the cornea is not a vascular tissue, the eye heals slowly following injury or surgery. The use of EGF can stimulate cell proliferation in the corneal epithelium, thus stimulating epithelialization during wound healing.199 Other growth factors that have a physiological role in corneal wound healing include platelet-derived growth factor,200 insulinlike growth factor,201 and transforming growth factor-p.202
Cyclosporin A is another peptide that may have a role in inhibiting the rejection of corneal grafts. Administration of 2% cyclosporin A in olive oil as eyedrops has been reported to result in a high concentration of the drug in the cornea and conjunctiva, but no intraocular penetration was observed. However, penetration into intraocular tissues can be achieved by formulation changes.203 204 Tissue plasminogen activator (tPA) is another protein that may find topical use to achieve clot lysis in the eye. Though tPA is approved by the FDA for lysis of thrombi in coronary arteries, its use in ophthalmology represents a nonapproved indication for an approved drug. In a study with ten patients who developed complications that threatened the successful outcome of anterior segment surgery, tPA completely or almost completely dissolved clots within 30 min to a few hours after tPA injection, and 100% resolution of fibrin and blood clots was observed at the first follow-up.205 Other peptides and proteins that may have a potential use following topical ocular delivery include calcitonin gene-related peptide,206 207 cholecystokinin,207 interleukin 6,208 g-inter-feron,209 substance P,210 and TRH.211
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Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...