A recent study has identified an increased risk of a rare form of vision loss, known as non-arteritic anterior ischemic optic neuropathy (NAION), in patients using Novo Nordisk (NYSE:NVO) A/S's diabetes medication Ozempic. The research, which corroborates findings from a Harvard University study earlier this year, showed that users of Ozempic were more than twice as likely to be diagnosed with NAION compared to those on a different type of diabetes drug.
The study, which has not yet been peer-reviewed, was published on medRxiv on December 11 and involved an analysis of patient records from Denmark and Norway. The researchers, however, could not establish if Ozempic's sister drug Wegovy, used for obesity, had a similar effect due to insufficient data.
NAION is caused by reduced blood flow to the optic nerve and is most common in individuals over 50. While diabetes, heart disease, and sleep apnea can increase the risk of developing NAION, the condition remains very rare. In the study, there were only 1.4 additional cases of NAION per 10,000 years of patient observation among those who took Ozempic.
Despite the low incidence rate, NAION is a serious condition that can lead to irreversible and untreatable vision loss. The authors of the study, affiliated with the University of Southern Denmark, the Norwegian Institute of Public Health, and the University of Copenhagen, emphasized the importance of balancing the potential risk of NAION against the significant benefits of semaglutide, the active ingredient in both Ozempic and Wegovy.
Novo Nordisk has reviewed the study alongside its internal safety assessments and maintains that the risk-benefit profile of its products remains positive. The company reported very few cases of NAION in its own trials, with no significant disparity against its drugs.
Following the release of the study, Novo Nordisk's shares dropped by up to 3.7% on Friday, marking the most significant decline in about a month.
The research team compared the incidence of NAION among new users of semaglutide and those on older SGLT-2 inhibitor drugs, tracking over 44,000 Ozempic patients in Denmark and more than 16,000 in Norway from the start of 2018 until June 2024 in Denmark and May 2022 in Norway. They identified 32 cases of NAION across this patient group. The study did not provide conclusive results for Wegovy, which was introduced in Denmark in 2022 and Norway in early 2023, due to a lack of patient data.
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