Ruzurgi for Children and Adults With LEMS Returning to Canada

Federal appeals court restores Health Canada's 2020 approval of oral treatment

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by Mary Chapman |

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A decision by the Federal Court of Appeal of Canada is restoring the availability of Ruzurgi (amifampridine) to treat children and adults with Lambert-Eaton Myasthenic Syndrome (LEMS) in that country, Medunik Canada announced.

Specifically, the court returned for a second time the notice of compliance, or approval, given to Ruzurgi by Health Canada in August 2020 as an oral LEMS treatment for patients ages 6 and older. The treatment was developed by Jacobus Pharmaceuticals and marketed in Canada by Medunik.

That approval was challenged in Canada by Catalyst Pharmaceuticals, which developed Firdapse, an oral LEMS treatment for patients ages 17 and older, whose active ingredient also is amifampridine. Catalyst argued that Jacobus’ application was invalid because it drew on data generated in studies of Firdapse, also approved in Canada in August 2020 under terms giving it years of marketing exclusivity.

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Ruzurgi, approved for patients ages 6 and older, works to improve muscle strength

Likewise, Ruzurgi’s U.S. approval was successfully challenged by Catalyst on similar grounds, leading the U.S. Food and Drug Administration to vacate its 2019 decision favoring this pediatric and adult treatment.

Medunik announced that it is working to re-establish Canadian availability of Ruzurgi, an oral potassium channel blocker to improve muscle strength in LEMS patients.

In granting the compliance notice, the appeals court confirmed the “reasonableness” of Health Canada’s regulatory review, the company stated.

“Our position has always been that we were not at fault in these unique proceedings and have always been confident that the facts would result in a positive outcome,”  Éric Gervais, president of Duchesnay Pharmaceutical Group, said in the release. Medunik Canada is a division of that group.

Ruzurgi’s approval in Canada was first suspended in a court ruling in June 2021. It was then reinstated later that month before being withdrawn again in March 2022. The recent federal court ruling sets aside that March decision by a trial division court.

“We are very pleased by the Court of Appeal’s decision confirming that the Notice of Compliance for Ruzurgi had been rightly granted by Health Canada,” said Alain M. Leclerc, vice president of legal affairs at Medunik.

In LEMS, self-reactive antibodies target and destroy voltage-gated calcium channels found in nerve cell endings. These protein channels are required for the release of acetylcholine, a signaling molecule that that sets in motion a series of events resulting in muscle contraction.

Amifampridine binds to voltage-gated potassium channels, blocking them. This prevents nerve cells from resetting after a nerve signal has been sent, giving the remaining healthy calcium channels more time to remain open. Essentially, it increases the amount of acetylcholine released from nerve cell endings to help strengthen muscles.