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Generic Name: amifampridine (AM i FAM pri deen)
Brand Name: Firdapse
Dosage Forms: oral tablet (10 mg)

Medically reviewed by on Feb 1, 2019. Written by Cerner Multum.

What is amifampridine?

Amifampridine is used to treat Lambert-Eaton myasthenic syndrome in adults.

Amifampridine may also be used for purposes not listed in this medication guide.

Important Information

Amifampridine can cause seizures, even if you have never had a seizure in the past. Stop taking amifampridine and call your doctor right away if you have a seizure.

Before taking this medicine

You should not use amifampridine if you are allergic to it, or if:

  • you have had a seizure in the past; or

  • you are allergic to dalfampridine.

Tell your doctor if you have ever had:

  • a seizure;

  • liver disease;

  • kidney disease; or

  • if you also take a form of amifampridine obtained from a compounding pharmacy (3,4-diaminopyridine or 3,4-DAP).

Tell your doctor if you are pregnant or breast-feeding.

How should I take amifampridine?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

You may take amifampridine with or without food.

Do not take more than 2 tablets at one time. Do not take more than 8 tablets in 24 hours.­

The amifampridine tablet may be split in half if needed.

Store at room temperature away from moisture and heat.

Throw away any amifampridine not used before the expiration date on the medicine label.

What happens if I miss a dose?

Skip the missed dose and use your next dose at the regular time. Do not use two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking amifampridine?

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Amifampridine side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Amifampridine can cause seizures, even if you have never had a seizure in the past.

Stop using amifampridine and call your doctor at once if you have a seizure.

Common side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Amifampridine dosing information

Usual Adult Dose for Lambert-Eaton Myasthenic Syndrome:

Initial dose: 15 mg to 30 mg orally daily in divided doses (3 to 4 times daily); dose may be increased by 5 mg daily every 3 or 4 days
-Maximum single dose: 20 mg
-Maximum daily dose: 80 mg/day
-If a dose is missed, patients should not take double or extra doses.

Use: For the treatment of Lambert-Eaton myasthenic syndrome (LEMS) in adults

What other drugs will affect amifampridine?

Amifampridine can cause seizures, especially if you also use certain medicines for infections, asthma, depression, mental illness, attention deficit disorder, or severe pain.

Many drugs can affect amifampridine. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here. Tell your doctor about all your current medicines and any medicine you start or stop using.

Frequently asked questions

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.