GLP-1 RA risk warning issued by TGA as specialists weigh prescribing evidence

The Therapeutic Goods Administration (TGA) has issued a safety update highlighting the association between glucagon-like peptide-1 receptor agonist (GLP-1 RA) medicines and non-arteritic anterior ischaemic optic neuropathy (NAION). However, ophthalmologists say the current evidence does not warrant widespread changes to prescribing practices.

The warning came after several GLP-1 RAs were linked to 36 cases of reported NAION in Australia, which is a rare but serious condition. Sometimes referred to as an ‘eye stroke’, it occurs when blood flow to the optic nerve is suddenly reduced or blocked. It can cause sudden and potentially permanent vision loss, and there is currently no treatment shown to improve visual acuity outcomes following NAION.

The TGA has updated the Product Information (PI) for GLP-1 RA medicines to include warnings about reported cases of NAION. Medicines currently marketed in Australia for type 2 diabetes and obesity include Trulicity (dulaglutide), Ozempic and Wegovy (semaglutide), Mounjaro (tirzepatide) and Saxenda (liraglutide).

The update comes as use of GLP-1 RA medicines has expanded rapidly across the nation. More than one million Australians have been dispensed a GLP-1 RAs over the past five years, fuelling the emergence of an exclusively private obesity treatment ecosystem. This is in addition to approximately 500,000 people who access these medicines for diabetes through the Pharmaceutical Benefits Scheme (PBS).

Evidence behind the safety update includes a recent meta-analysis involving more than 1.5 million patients, which found GLP-1 RA use was associated with an increased risk of NAION. Among GLP-1 RA users, the risk of NAION was 0.09%, representing an absolute risk difference of 0.037% and a number needed to harm of approximately 2,700.

Despite the regulatory update, the Royal Australian and New Zealand College of Ophthalmologists (RANZCO) said the available evidence does not support changing routine prescribing practices.

“Current data do not justify broad changes to prescribing practices for GLP-1 receptor agonists in Australia and New Zealand. The Neuro-Ophthalmology Society of Australia (NOSA) supports continued use of these agents according to established metabolic indications, alongside careful patient counselling, interdisciplinary collaboration and ongoing surveillance for rare neuro-ophthalmic adverse events,” said RANZCO is a position statement.

An anatomical predisposition, sometimes described as a ‘disc at risk’, may be identified by an optometrist or ophthalmologist. However, the safety update does not establish a requirement for routine screening of every asymptomatic person taking a GLP-1 RA. Any sudden vision loss, including partial loss of vision, requires urgent ophthalmological assessment.

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