FDA orders blindness risk warning to GLP-1 agonist labels

The FDA has ordered all GLP-1 receptor agonist manufacturers to add a warning to the label of their products for a rare eye condition – non-arteritic anterior ischemic optic neuropathy (NAION) – which can cause sudden blindness.

The warning affects top-selling drugs for weight-loss and type 2 diabetes from Eli Lilly and Novo and draws attention to the "acute, painless, decreased vision in one eye, including permanent vision loss," that can occur with NAION, sometimes called an 'eye stroke'.

NAION is caused by decreased blood flow to the front part of the optic nerve, but the underlying cause is not completely understood, according to the FDA's order notice. Risk factors may include smoking, diabetes, high blood pressure, sleep apnoea, anaemia, and kidney disease.

Last year, the EMA carried out a review of Novo Nordisk's GLP-1 agonist semaglutide – used in its Ozempic and Wegovy products – which concluded that NAION is a "very rare side effect" of the drug that may affect "up to 1 in 10,000 people" taking the drug for at least a year.

The FDA's review – which the agency said spanned "clinical trial data, animal data, and postmarketing data, including observational studies and case reports" – concluded that NAION cases have been reported for all of the currently marketed GLP-1 agonists, with a rate of approximately six in 100,000 users. That included Lilly's dual GIP/GLP-1-acting tirzepatide, which is sold under the Zepbound and Mounjaro brand names in the US.

Even at these relatively low rates, the sheer number of people taking GLP-1 agonist medicines for weight loss and diabetes around the world – 100 million, according to World Health Organization (WHO) estimates – means that thousands of people could be at risk of irreversible vision loss.

Novo said that patient safety is its top priority, and while it does not believe there is a clear cause-and-effect relationship between semaglutide and NAION, it recognises the seriousness of a condition that can have "a profound impact on patients and their families." It added that it remains "confident in the benefit-risk profile of our GLP-1 medicines."

Lilly, meanwhile, said it is "carefully evaluating the update and will respond to the FDA promptly," adding that it will also "continue to monitor the tirzepatide development programme for all indications to evaluate any new safety signals."

Both companies are facing lawsuits from patients who are claiming they suffered vision loss as a result of exposure to their GLP-1 medicines.

Photo by Maxim Tolchinskiy on Unsplash

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