Statins may increase the risk of myasthenia gravis and ocular myasthenia

A Health Canada safety review concluded that there is a possible link between statin (HMG-CoA reductase inhibitor) use and the risk of myasthenia gravis, including ocular myasthenia. This neuromuscular condition causes weakness of the voluntary muscles of the body, including those that control the eyes and eyelids. The safety review was triggered by a labelling update for all statin products by the European Medicines Agency. The Health Canada safety review included information provided by manufacturers, and from searches of the Canada Vigilance database, international databases and the scientific literature.A total of 31 cases (2 Canadian and 29 international) of myasthenia gravis and/or ocular myasthenia in patients taking statins were examined during the Health Canada safety review. Of the 31 cases, 27 (1 Canadian) were determined to be possibly linked to the use of statins, one was unlikely to be linked and three (1 Canadian) could not be assessed due to missing information. Of the possible cases, three had recurrence of symptoms of myasthenia gravis and/or ocular myasthenia when treated with different statins, which suggests a drug class effect for this risk.Health Canada also reviewed four studies published in the scientific literature. Despite the limitations of these studies, they provided evidence supporting a link between statins and worsening myasthenia gravis and/or ocular myasthenia. Evidence of a link between statins and new occurrence of myasthenia gravis and/or ocular myasthenia in published studies was limited; however, published case reports support a possible link.The safety review concluded that this is a class effect, applying to all marketed statins (atorvastatin, fluvastatin, lovastatin, pravastatin, rosuvastatin and simvastatin). Therefore, Canadian product monographs for all statin products are being updated to include the potential risk of myasthenia gravis and ocular myasthenia.Consumers and healthcare professionals are encouraged to report any side effects related to the use of statins to the Canada Vigilance Program (https://www.canada.ca/en/health-canada/services/drugs-health-products/medeffect-canada/canada-vigilance-program.html). Read: Pseudoephedrine: risk of PRES/RCVSThe occurrence of myasthenia gravis and ocular myasthenia with statins appears to be very rare, based on the very few number of case reports despite widespread statin use. Statins have been marketed in Canada since 1995. About 282 million prescriptions for statins were dispensed by Canadian retail pharmacies between 2018 and 2023. The Health Canada safety review and subsequent product monograph changes will draw attention to this possible adverse effect of statins and alert healthcare providers to recognize that it may occur. Reference1. Health Canada. Summary safety review - HMG-CoA reductase inhibitors (atorvastatin, fluvastatin, lovastatin, pravastatin, rosuvastatin and simvastatin) - statins - assessing the potential risk of myasthenia gravis, including ocular myasthenia. December 11, 2024. https://dhpp.hpfb-dgpsa.ca/review-documents/resource/SSR1732733593751 (accessed December 12, 2024). Keep up to date on potential drug risks by following Sandra Knowle’s ADVERSE REACTIONS column.

Statins may increase the risk of myasthenia gravis and ocular myasthenia

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