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NUCCA News - B Vitamin Derivative May Fight Diabetic Eye Damage Mon Feb 17,10:58 AM ET Add Health - Reuters to My Yahoo! By Amy Norton NEW YORK (Reuters Health) - A compound derived from the B vitamin thiamine has shown early promise in preventing diabetic retinopathy, a potentially blinding complication of diabetes. In experiments with diabetic rats, scientists found that the drug, called benfotiamine, completely prevented the blood vessel damage that marks retinopathy. Benfotiamine is a synthetic derivative of thiamine (vitamin B1) that has been prescribed in Europe for more than a decade for various conditions, including diabetes-related nerve damage. But the drug has never been formally tested in rigorous clinical trials. Now the new study provides a molecular mechanism by which benfotiamine might prevent diabetic retinopathy, and possibly other complications of the disease, according to lead author Dr. Michael Brownlee of Albert Einstein College of Medicine in New York. And what's "very exciting," he told Reuters Health, is that because people have already used the drug safely for years, its journey to clinical trials--and, if all goes well, to diabetics (news - web sites)--could be a relatively quick one. The findings are being published Tuesday in Nature Medicine's advance online edition. Diabetic retinopathy involves damage to the tiny capillaries that supply the retina, the light-sensitive tissue at the back of the eye. If it progresses to an advanced stage, abnormal new blood vessels grow in the retina, and--if not treated promptly--the disease can cause blindness. The blood vessel damage seen in retinopathy results from the chronically high blood-sugar levels that mark diabetes. Unlike most body cells, which can keep their internal sugar levels in check, the endothelial cells that line the body's blood vessels take on high sugar levels when blood sugar is elevated, Brownlee explained. But in their experiments, he and his colleagues found that benfotiamine is able to block the major molecular "pathways" by which high sugar levels damage blood vessel cells. It does so by activating an enzyme called transketolase, which is normally dependent on thiamine. The researchers tested benfotiamine rather than thiamine itself because the fat-soluble synthetic compound is far more "bioavailable" in the body. It boosts activity in transketolase by 200% to 300%, Brownlee said, as opposed to the 20% increase thiamine provides. Because there's no evidence that thiamine itself might fight diabetic retinopathy, he said, "I would caution people against taking thiamine supplements" for that purpose. Vascular damage is at the foundation of other major diabetes complications, including coronary artery disease and kidney failure. Because of this, Brownlee said there is "absolutely" potential for benfotiamine in the prevention of these complications as well--although much more work lies ahead. But the early results are exciting, he said, because "right now, there's absolutely no drug to prevent diabetic complications." SOURCE: Nature Medicine 2003;10.1038/nm834. http://story.news.yahoo.com/news?tmpl=story2&cid=571 |
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