Novo Nordisk obesity drug linked to rare cause of sight loss

Novo Nordisk's GLP-1 agonist semaglutide, used to treat diabetes and obesity, may cause a serious eye condition that can lead to the loss of vision, according to the EU medicines regulator.

After a review that started last December, the EMA's PRAC safety committee has concluded that the Danish pharma group's Wegovy, Ozempic, and Rybelsus products – all based on semaglutide – have a condition known as non-arteritic anterior ischaemic optic neuropathy (NAION) as a "very rare side effect."

The EMA is the first regulatory authority to conclude that there is a link between the drug and NAION, and has estimated it may affect "up to 1 in 10,000 people" taking the drug for at least a year.

In April, a US man who lost his sight due to NAION filed a lawsuit against Novo Nordisk, claiming that the use of Ozempic for his type 2 diabetes was responsible. He was prescribed Ozempic around August 2023 and diagnosed with NAION in December 2023. Meanwhile, a class action suit filed in Pennsylvania is reported to be representing more than 1,000 claimants.

NAION is a rare eye condition that is nonetheless the second-leading cause of optic nerve blindness after glaucoma.

Various papers have pointed to a link between the condition and semaglutide, including an observational study published in the journal JAMA Ophthalmology last year, which looked at registry data involving more than 17,000 Mass Eye and Ear patients treated over the six years since semaglutide was first launched.

"Results from several large epidemiological studies suggest that exposure to semaglutide in adults with type 2 diabetes is associated with an approximately two-fold increase in the risk of developing NAION compared with people not taking the medicine," said the EMA in a statement on the PRAC deliberations.

The agency has recommended that semaglutide's labelling be updated to include a warning that if patients experience a sudden loss of vision or rapidly worsening eyesight during treatment with semaglutide, they should contact their doctor without delay.

Barclays analyst Emily Field told Reuters that NAION "has been reported as a potential risk for some time, so I think the clinical community is relatively aware of it. I don't see this as making any major difference to prescribing patterns."

Novo Nordisk's share price was unaffected by the report, actually strengthening in the wake of the PRAC announcement, suggesting investors share that sentiment.

Photo by Manuel bonadeo on Unsplash