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FDA Approves Firdapse for Rare Autoimmune Disorder

FDA news release; 2018 Nov 28

The US Food and Drug Administration (FDA) has approved Firdapse (amifampridine) tablets for the treatment of Lambert-Eaton myasthenic syndrome (LEMS) in adults. LEMS is a rare autoimmune disorder that affects the connection between nerves and muscles and causes weakness and other symptoms in affected patients. This is the first FDA approval of a treatment for LEMS.

The FDA granted the approval of Firdapse to Catalyst Pharmaceuticals, Inc., headquartered in Coral Gables, FL.

Indications: Firdapse is a potassium channel blocker indicated for the treatment of

LEMS in adults.

Dosage/administration: The recommended starting dosage is 15 mg to 30 mg daily taken orally

in divided doses (3 to 4 times daily). Starting dosage is 15 mg daily for patients with renal impairment, hepatic impairment, and in known N-acetyltransferase 2 (NAT2) poor metabolizers. Dosage can be increased by 5 mg daily every 3 to 4 days, but is not to exceed a maximum of 80 mg daily. The maximum single dose is 20 mg.

Adverse reactions: The most common (> 10%) adverse reactions are: paresthesia, upper

respiratory tract infection, abdominal pain, nausea, diarrhea, headache, elevated liver enzymes, back pain, hypertension, and muscle spasms.


FDA approves first treatment for Lambert-Eaton myasthenic syndrome, a rare autoimmune disorder. [news release]. Coral Gables, Florida: Catalyst Pharmaceuticals, Inc. November 28, 2018. Accessed November 30, 2018.

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