The 11th Circuit Court of Appeals has denied Jacobus Pharmaceutical’s petition for rehearing of a prior ruling to overturn the FDA’s approval of Ruzurgi (amifampridine) for pediatric patients with the autoimmune disease Lambert-Eaton myasthenic syndrome (LEMS) based on the orphan drug exclusivity of Catalyst Pharmaceutical’s Firdapse.

Ruzurgi is a potassium channel blocker that has received an Orphan Drug designation from the FDA for treatment of LEMS in children age six to 16, but it has yet to be approved. Catalyst’s Firdapse has the same active ingredient as Ruzurgi and is approved for treating LEMS in adults.

In early October, a federal appeals court ruled that the FDA incorrectly approved Ruzurgi because Catalyst Pharmaceuticals already owned the rights to the drug.

Catalyst, which filed suit in the U.S. District Court for the District of Southern Florida in 2019, said it expects that the mandate to the District Court with instructions to enter summary judgment for Catalyst will be issued in the near future.