According to Zhitong Finance, a small study published in the American Medical Association Journal on Wednesday indicated that Novo Nordisk's best-selling weight loss drugs Ozempic and Wegovy may be associated with an increased risk of non-arteritic anterior ischemic optic neuropathy (NAION), a rare visual loss. Dragged down by this news, stocks related to weight loss drugs fell on Wednesday. Shaodi Biology and Novo Nordisk both fell nearly 3%, Altimmune and Viking Therapeutics fell over 2%, and Eli Lilly and Co. fell nearly 1%.

NAION refers to a reduction in blood flow to the optic nerve, which is the pipeline for transmitting visual signals from the eye to the brain. In people over 50, this is the most common cause of sudden optic nerve damage, affecting an estimated 10 in every 100,000 people.

Ozempic, which is used to treat diabetes, and Wegovy, which is used for weight loss, both contain the active ingredient semaglutide, a glucagon-like peptide-1 (GLP-1) receptor agonist that stimulates insulin secretion, suppresses glucagon secretion to slow gastric emptying, and reduces appetite, ultimately achieving the goal of lowering blood sugar and losing weight. Semaglutide, together with tirzepatide, Lilly's dual GIP and GLP-1 receptor agonist, dominates the market for hypoglycemic and weight-loss drugs in the United States.

Studies have shown that overweight or obese patients who receive GLP-1 drug semaglutide as treatment have more than seven times the likelihood of developing NAION than patients receiving non-GLP-1 drugs. At the same time, the risk of NAION for people with diabetes treated with semaglutide increased more than fourfold.

Researchers analyzed data from more than 16,000 patients undergoing treatment at the Massachusetts Eye and Ear hospital at Harvard University. Doctors found that patients using these drugs were significantly more likely to develop NAION than those using other drugs. They focused on 710 and 979 patients with diabetes or obesity/overweight who received GLP-1 and non-GLP-1 drugs as treatment options.

However, scientists noted that their study only focused on existing data and emphasized that more research is needed to confirm their findings. This study is limited in scope, based solely on patient records from Massachusetts Eye and Ear Hospital, and involves only 37 cases of eye disease, so its statistical power is limited. Therefore, Harvard University researchers and other experts say that the current research results are not enough to prove that these drugs are the direct cause of eye complications and that larger-scale verification is needed in more hospitals.