Official HCP Site | FIRDAPSE® (amifampridine)

Key insights regarding increased maximum daily dosing. Watch Video.

Key insights regarding increased maximum daily dosing. Watch Video.

The recommended first-line therapy for patients living with Lambert-Eaton myasthenic syndrome (LEMS)¹

Clinically proven to maintain muscle strength and mobility^2-4

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What is LEMS?

LEMS is a rare, immune-mediated neuromuscular disorder that results in progressive, debilitating muscle weakness and fatigue.^5,6

About FIRDAPSE

The only FDA-approved treatment for LEMS that’s clinically proven to maintain muscle strength and improve patient-reported sense of physical well-being vs placebo in clinical trials.^2-4,7

Discover Catalyst Pathways^®

Learn about all the ways that Catalyst programs and services support patients managing LEMS with FIRDAPSE.

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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:

Yoon CH, Owusu-Guha J, Smith A, Buschur P. Amifampridine for the management of Lambert-Eaton myasthenic syndrome: a new take on an old drug. Ann Pharmacother. 2020;54(1):56-63.
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.
Shieh P, Sharma K, Kohrman B, Oh SJ. Amifampridine phosphate (FIRDAPSE) is effective in a confirmatory phase 3 clinical trial in LEMS. J Clin Neuromuscul Dis. 2019;20(3):111-119.
Harms L, Sieb J-P, Williams AE, et al. Long-term disease history, clinical symptoms, health status, and healthcare utilization in patients suffering from Lambert Eaton myasthenic syndrome: results of a patient interview survey in Germany.J Med Econ. 2012;15(3):521-530.
National Organization for Rare Disorders (NORD) website. Rare disease database: Lambert-Eaton myasthenic syndrome. Accessed August 18, 2022. https://rarediseases.org/rare-diseases/lambert-eaton-myasthenic-syndrome/.
US Food and Drug Administration. Orange Book: Approved drug products with therapeutic equivalence evaluations. 44th ed. 2024:47, Amifampridine; p1944, U-2956.
Muppidi S, Wolfe GI, Barohn RJ. Diseases of the neuromuscular junction. In: Swaiman K, Ashwal S, Ferriero D, Schor N, eds. Pediatric Neurology: Principles and Practice. 5th ed. Philadelphia, PA: Elsevier; 2011:1549-1569.
Senanayake N, Roman GC. Disorders of neuromuscular transmission due to natural environmental toxins. J Neurol Sci. 1992;107:1-13.
National Organization for Rare Disorders (NORD) website. Rare disease database: Myasthenia gravis. Accessed December 9, 2022. https://rarediseases.org/rare-diseases/myasthenia-gravis/.
Sanders DB. Lambert-Eaton myasthenic syndrome: diagnosis and treatment. Ann NY Acad Sci. 2003;998:500-508.
Titulaer MJ, Lang B, Verschuuren JJ. Lambert-Eaton myasthenic syndrome: from clinical characteristics to therapeutic strategies. Lancet Neurol. 2011;10(12):1098-1107.
Gandhi L, Johnson BE. Paraneoplastic syndromes associated with small cell lung cancer. J Natl Compr Canc Netw. 2006;4(6):631-638.
Titulaer MJ, Wirtz PW, Willems LNA, et al. Screening for small-cell lung cancer: a follow-up study of patients with Lambert-Eaton myasthenic syndrome. J Clin Oncol. 2008;26(26):4276-4281.
Wirtz PW, Wintzen AR, Verschuuren JJ. Lambert-Eaton myasthenic syndrome has a more progressive course in patients with lung cancer. Muscle Nerve. 2005;32(2):226-229.
Wirtz PW, Smallegange TM, Wintzen AR, Verschuuren JJ. Differences in clinical features between the Lambert-Eaton myasthenic syndrome with and without cancer: an analysis of 227 published cases. Clin Neurol Neurosurg. 2002;104(4):359-363.
Tarr TB, Wipf P, Meriney SD. Synaptic pathophysiology and treatment of Lambert-Eaton myasthenic syndrome. Mol Neurolbiol. 2015;52(1):456-463.
Lehnerer S, Herdick M, Stegherr R, et al. Burden of disease in Lambert-Eaton myasthenic syndrome: taking the patient’s perspective. J Neurol. 2024;271:2824–2839.
Maddison P, Lang B, Mill K, Newsom-Davis J. Long term outcome in Lambert-Eaton myasthenic syndrome without lung cancer. J Neurol Neurosurg Psychiatry. 2001;70(2):212-217.
Merino-Ramírez MÁ, Bolton CF. Review of the diagnostic challenges of Lambert-Eaton syndrome revealed through three case reports. Can J Neurol Sci. 2016;43(5):635-647.
Gilhus NE. Lambert-Eaton myasthenic syndrome; pathogenesis, diagnosis, and therapy. Autoimmune Dis. 2011;2011:973808.
Kesner VG, Oh SJ, Dimachkie MM, Barohn RJ. Lambert-Eaton myasthenic syndrome. Neurol Clin. 2018;36(2):379-394.
Lipka AF, Boldingh MI, van Zwet EW, et al. Long-term follow-up, quality of life, and survival of patients with Lambert-Eaton myasthenic syndrome. Neurology. 2020;94(5):e511-e520.
Referenced with permission from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Small Cell Lung Cancer (V.1.2025). © National Comprehensive Cancer Network, Inc. 2024. All rights reserved. Accessed September 10, 2024. To view the most recent and complete version of the guideline, go to NCCN.org.
Young JD, Leavitt JA. Lambert-Eaton myasthenic syndrome: ocular signs and symptoms. J Neuroophthalmol. 2016;36(1):20-22.
Titulaer JM, Wirtz PW, Wintzen AR, et al. Lambert-Eaton myasthenic syndrome with pure ocular weakness. Neurology. 2008;70(1):86-87.
Gordon LK. Paraneoplastic syndromes in neuro-ophthalmology. J Neuroophthalmol. 2015;35(3):306-314.
Quartel A, Turbeville S, Lounsbury D. Current therapy for Lambert-Eaton myasthenic syndrome: development of 3,4-diaminopyridine phosphate salt as first-line symptomatic treatment. Curr Med Res Opin. 2010;26(6):1363-1375.
Wirtz PW, Verschuuren JJ, van Dijk JG, et al. Efficacy of 3,4-diaminopyridine and pyridostigmine in the treatment of Lambert-Eaton myasthenic syndrome: a randomized, double-blind, placebo-controlled, crossover study. Clin Pharmacol Ther. 2009;86(1):44-48.
Ivanovski T, Miralles F. Lambert-Eaton myasthenic syndrome: early diagnosis is key. Degener Neurol Neuromuscul Dis. 2019;9:27-37.
Bain PG, Motomura M, Newsom-Davis J, et al. Effects of intravenous immunoglobulin on muscle weakness and calcium-channel autoantibodies in the Lambert-Eaton myasthenic syndrome. Neurology. 1996;47(3):678-683.
Chalk CH, Murray NM, Newsom-Davis J, O’Neill JH, Spiro SG. Response of the Lambert-Eaton myasthenic syndrome to treatment of associated small-cell lung carcinoma. Neurology. 1990;40(10):1552-1556.
Oh SJ, Sieb J-P. Update on amifampridine as a drug of choice in Lambert-Eaton myasthenic syndrome. US J Neurol.2014;10(2):83-89.
Strupp M, Teufel J, Zwergal A, et al. Aminopyridines for the treatment of neurologic disorders. Neurol Clin Pract. 2017;7(1):65-76.
Lindquist S, Stangel M. Update on treatment options for Lambert-Eaton myasthenic syndrome: focus on use of amifampridine. Neuropsychiatr Dis Treat. 2011;7:341-349.
Data on file, Catalyst Pharmaceuticals.
Verschuuren J, Strijbos E, Vincent A. Neuromuscular junction disorders. Handb Clin Neurol. 2016;133:447-466.
Dodson PD, Forsythe ID. Presynaptic K+ channels: electrifying regulators of synaptic terminal excitability. TINS. 2004;27(4):210-217.
Jacob S, Muppidi S, Guidon A, et al; International MG/COVID-19 Working Group. Guidance for the management of myasthenia gravis (MG) and Lambert-Eaton myasthenic syndrome (LEMS) during the COVID-19 pandemic. J Neurol Sci. 2020;412:116803.