Muscle-relaxant OrfenAce 100 mg tablets recalled because of nitrosamine impurity

Issue

SteriMax Inc. is recalling OrfenAce 100 mg tablets after testing identified a nitrosamine impurity above what is considered acceptable if the drug were to be taken over a lifetime. OrfenAce (a brand name for orphenadrine citrate) is an over-the-counter muscle relaxant used to relieve muscle spasms.

The nitrosamine impurity found in OrfenAce is called NMOA (N-methyl-N-nitroso-2-[(2 methylphenyl) phenylmethoxy]ethanamine). Nitrosamine impurities are possible or probable human carcinogens. This means that long-term exposure to a level above what is considered safe may increase the risk of cancer.

We are all exposed to low levels of nitrosamines through a variety of foods (such as smoked and cured meats, dairy products and vegetables), drinking water and air pollution. Health Canada does not expect that a nitrosamine impurity will cause harm when exposure is at or below the acceptable level. For example, no increase in the risk of cancer is expected if exposure to the nitrosamine impurity below the acceptable level occurs every day for 70 years.

Health Canada is advising that there is no immediate risk to patients taking this medication since the potential risk of cancer is with long-term (every day for 70 years) exposure to nitrosamine impurities that exceeds safe levels, which is not what is expected to occur with patients taking the affected medication for a short period of time. Patients should seek an alternative muscle relaxant to relieve their muscle spasms.

Health Canada is monitoring the effectiveness of the recall and the company’s implementation of any necessary corrective and preventative actions. Should any additional recalls be deemed necessary, Health Canada will update the table below and inform Canadians.

Products affected

The recall affects all lots within expiry on the market:

• Seek an alternative muscle relaxant to relieve your muscle spasms at your earliest convenience.
• Talk to your healthcare provider if you have taken a recalled product and have concerns about your health.
• Contact SteriMax Inc. at medinfo@sterimaxinc.com or by calling 1-800-881-3550, extension 5, if you have questions about the recall.
• Report any health product-related side effects or complaints to Health Canada.

Health Canada has been working to address the issue of nitrosamine impurities found in certain medications since the summer of 2018. Companies were directed to complete detailed evaluations of their manufacturing processes by the end of March 2021, and are testing products if their reviews identified a potential for nitrosamine formation. As this work progresses, additional products may be identified and recalled as appropriate. Health Canada continues to work closely with international regulatory partners and companies to address the issue and will continue to keep Canadians informed. More information on Health Canada’s work to address nitrosamines in medications is available on Canada.ca