The Food and Drug Administration’s (FDA) marketing approval of Jacobus Pharmaceutical’s Ruzurgi (amifampridine) for the treatment of Lambert-Eaton myasthenic syndrome (LEMS) in pediatric patients is no longer valid, according to a press release issued by Catalyst Pharmaceuticals.

In 2019, Catalyst filed a suit against the FDA regarding its approval of Ruzurgi, alleging that the FDA violated Catalyst’s statutory rights to Orphan Drug Exclusivity for Firdapse (amifampridine) for the treatment of LEMS. The FDA’s Orphan Drug Exclusivity blocks the approval of the same product for the same indication for 7 years.

On January 28, 2022, the US Court of Appeals for the 11th Circuit issued a mandate directing the District Court that heard Catalyst’s claim against the FDA to enter summary judgment in favor of the Company.

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Firdapse received FDA approval in November 2018 for the treatment of adults with LEMS. Amifampridine is a nonspecific, voltage-dependent, potassium channel blocker. 

To help transition patients currently being treated with Ruzurgi to Firdapse, Catalyst has provided a patient assistance team. Additional information is available by calling (833) 422-8259 or visiting

“The entire Catalyst patient assistance team has been preparing for this likely outcome since the decision of the US Circuit Court of Appeals for the 11th Circuit was reported”, said Patrick J. McEnany, Catalyst’s Chairman and CEO. “We have added additional care coordinators to our Catalyst Pathways team, and our entire patient-focused team is ready to assist LEMS patients that are currently being treated with Ruzurgi to provide a smooth, uninterrupted transition to Firdapse.”


  1. Catalyst Pharmaceuticals reports that the FDA marketing approval previously granted for Ruzurgi® is no longer valid. News release. Catalyst Pharmaceuticals, Inc. Accessed February 3, 2022.
  2. Catalyst Pharmaceuticals files federal lawsuit against US Food and Drug Administration. News release. Catalyst Pharmaceuticals, Inc. June 12, 2019. Accessed February 3, 2022.

This article originally appeared on MPR