Firdapse (amifampridine, Catalyst Pharmaceuticals) tablets have been approved by the FDA for the treatment of Lambert-Eaton myasthenic syndrome (LEMS) in adults. The rare autoimmune disorder affects the connection between nerves and muscles and causes weakness and other symptoms in affected patients.
Around three in one million individuals worldwide are believed to have LEMS. Patients suffer from significant weakness and fatigue that often causes great difficulties with daily activities. LEMS may be associated with other autoimmune diseases, but typically occurs in patients with cancer such as small cell lung cancer.
In two clinical trials, patients receiving amifampridine experienced a greater benefit than those taking placebo. The most common side effects reported were paresthesia, upper respiratory tract infection, abdominal pain, nausea, diarrhea, headache, elevated liver enzymes, back pain, hypertension, and muscle spasms. In addition, seizures have been observed in patients with no history of seizures.
The FDA granted amifampridine priority review, breakthrough therapy, and orphan drug designations.
Source: FDA, November 28, 2018