About FIRDAPSE | FIRDAPSE® (amifampridine)

The only FDA-approved LEMS treatment for adults and pediatric patients 6 years of age and older^1,2

A UNIQUE COMPOUND

FIRDAPSE was the first FDA-approved therapy containing amifampridine, a voltage-gated potassium channel blocker that targets the presynaptic nerve terminal of neuromuscular junctions.^33-35*

Chemical structure of FIRDAPSE compound — Amifampridine phosphate
(3,4-diaminopyridine phosphate)

EXTENSIVELY TESTED

FIRDAPSE has been tested in more than 70 clinical and nonclinical studies, including two positive Phase 3 studies, over a 9‑year period.^2,36

In clinical trials, FIRDAPSE demonstrated clinically meaningful preservation in muscle strength and patient satisfaction^2-4:

Chemical structure of FIRDAPSE compound — Amifampridine phosphate
(3,4-diaminopyridine phosphate)

CHANGING LIVES

people in the US are living with the challenges of LEMS¹¹

people have put their lives back in motion with FIRDAPSE³¹

*The mechanism by which FIRDAPSE exerts its therapeutic effect in patients with LEMS has not been fully elucidated.
FIRDAPSE is a broad-spectrum potassium channel blocker.²

FIRDAPSE MECHANISM OF ACTION (MOA)

Illustrated rendering of FIRDAPSE MOA

SEE THE FULL MECHANISM OF ACTION (MOA) STORY FOR LEMS AND FIRDAPSE

Watch the full MOA animation video to better understand normal neuromuscular transmission, how LEMS disrupts this process, and how FIRDAPSE helps restore it.

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Indication and Important Safety Information

INDICATIONS AND USAGE:

FIRDAPSE is a potassium channel blocker indicated for the treatment of Lambert-Eaton myasthenic syndrome (LEMS) in adults and pediatric patients 6 years of age and older.

CONTRAINDICATIONS

FIRDAPSE is contraindicated in patients with:

A history of seizures
Hypersensitivity to amifampridine phosphate or another aminopyridine

WARNINGS AND PRECAUTIONS

Seizures: FIRDAPSE can cause seizures. Consider discontinuation or dose-reduction of FIRDAPSE in patients who have a seizure while on treatment.

Hypersensitivity: If a hypersensitivity reaction such as anaphylaxis occurs, FIRDAPSE should be discontinued and appropriate therapy initiated.

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.

Please see full Prescribing Information for additional Important Safety Information.

To report SUSPECTED ADVERSE REACTIONS, contact Catalyst Pharmaceuticals at 1-844-347-3277 (1-844-FIRDAPSE) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

References:

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Full Prescribing Information for FIRDAPSE (amifampridine). Catalyst Pharma; 2024.
Oh SJ, Scherbakova N, Kostera-Pruszczyk A, et al; LEMS Study Group. Amifampridine phosphate (FIRDAPSE®) is effective and safe in a phase 3 clinical trial in LEMS. Muscle Nerve. 2016;53(5):717-725.
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