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Some exclusions apply.

What’s in FIRDAPSE®?

Each tablet of FIRDAPSE includes 18.98 mg of amifampridine phosphate that is the equivalent to 10 mg of amifampridine freebase as found in 3,4-diaminopyridine freebase (often called 3,4-DAP or DAP), which was available to some LEMS patients through a compassionate-use program for years.

FIRDAPSE Blister Pack and Pill Bottle

Why does FIRDAPSE have phosphate (salt) in it?

FIRDAPSE utilizes a phosphate salt in the amifampridine structure to stabilize the amifampridine molecule, allowing FIRDAPSE to be stored at room temperature for long periods of time without losing potency and keeping it safe for others.

When FIRDAPSE is taken, the drug quickly separates into amifampridine (3,4-DAP) freebase and phosphate salt ions in your bloodstream.

Calcium phosphate is an ingredient found in many other pharmaceuticals and vitamins but not in FIRDAPSE, and its action in the body works in a similar way, separating into calcium ions and phosphate salt ions in your bloodstream.

Each tablet of FIRDAPSE includes 1.5 mg of phosphate, an essential nutrient that the human body needs. The US Centers for Disease Control and Prevention recommends a 700 mg/day allowance of phosphorus; a maximum daily dose of FIRDAPSE provides only 12 mg per day.

Are there any other ingredients?

Yes—FIRDAPSE also uses inactive ingredients to help form a tablet that includes calcium stearate, colloidal silicon dioxide, and microcrystalline cellulose.

All of these inactive ingredients are classified by the FDA as “generally recognized as safe” (GRAS) for this use and are considered hypoallergenic. Additionally, FIRDAPSE is gluten free.

Some other pharmaceutical products sometimes contain sodium starch glycolate, which may cause a reaction in gluten-sensitive people, but FIRDAPSE does not contain sodium starch glycolate.

The only other approved product that contains amifampridine (approved for an indication distinct and separate from that of FIRDAPSE) has 10 mg of 3,4-DAP freebase but also contains inactive ingredients such as colloidal silicon dioxide, dibasic calcium phosphate dihydrate, magnesium stearate, microcrystalline cellulose, and sodium starch glycolate.

Want to stay up to date?

Receive the latest information about FIRDAPSE and Lambert-Eaton myasthenic syndrome (LEMS).

What is FIRDAPSE®?

FIRDAPSE is a prescription medicine used to treat adults 17 years of age or older with Lambert-Eaton myasthenic syndrome (LEMS). The safety and efficacy of FIRDAPSE in patients under the age of 17 has not been established.

IMPORTANT SAFETY INFORMATION

What is the most important information I should know about FIRDAPSE?

  • FIRDAPSE can cause seizures.
    • You could have a seizure even if you never had a seizure before.
    • Do not take FIRDAPSE if you have ever had a seizure.

Stop taking FIRDAPSE and call your doctor right away if you have a seizure while taking FIRDAPSE.

Do not take FIRDAPSE if you:

  • have ever had a seizure
  • are allergic to amifampridine phosphate, or another aminopyridine.

Before you take FIRDAPSE, tell your doctor about all of your medical conditions, including if you:

  • are taking another aminopyridine, such as compounded 3,4-diaminopyridine (3,4-DAP)
  • have had a seizure
  • have kidney problems
  • have liver problems
  • are pregnant or plan to become pregnant. It is not known if FIRDAPSE will harm your unborn baby. You and your doctor will decide if you should take FIRDAPSE while you are pregnant.
  • are breastfeeding or plan to breastfeed. It is not known if FIRDAPSE passes into your breast milk. Talk to your doctor about the best way to feed your baby while taking FIRDAPSE.

Tell your doctor about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

How should I take FIRDAPSE?

  • Take FIRDAPSE exactly as your doctor tells you to take it. Do not change your dose of FIRDAPSE.
  • Do not take more than 2 tablets of FIRDAPSE at one time or more than 8 tablets of FIRDAPSE in a 24-hour period.
  • FIRDAPSE can be taken with or without food.
  • If you miss a dose of FIRDAPSE, skip that dose and take your next dose at your next scheduled dose time. Do not double your dose to make up the missed dose.
  • Do not take FIRDAPSE together with other medicines known to increase the risk of seizures.
  • If you take too much FIRDAPSE, call your doctor or go to the nearest hospital emergency room right away.

What are the possible side effects of FIRDAPSE?

FIRDAPSE may cause serious side effects, including:

  • Seizures. See "What is the most important information I should know about FIRDAPSE?"
  • Serious allergic reactions, such as anaphylaxis. FIRDAPSE can cause serious allergic reactions. Stop taking FIRDAPSE and call your doctor right away or get emergency medical help if you have:
    • shortness of breath or trouble breathing
    • swelling of your throat or tongue
    • ­hives
  • The most common side effects of FIRDAPSE include:
    • tingling around the mouth, tongue, face, fingers, toes, and other body parts
    • upper respiratory infection
    • stomach pain
    • nausea
    • diarrhea
    • headache
    • increased liver enzymes
    • back pain
    • high blood pressure
    • muscle spasms

Tell your doctor if you have any side effect that bothers you or that does not go away.

These are not all the possible side effects of FIRDAPSE.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

How should I store FIRDAPSE?

  • Store FIRDAPSE at 68ºF to 77ºF (20ºC to 25ºC).
  • Safely throw away FIRDAPSE that is out of date or no longer needed.

Keep FIRDAPSE and all medicines out of the reach of children.

If you would like more information, talk to your doctor or pharmacist. You can ask your pharmacist or doctor for additional information about FIRDAPSE that is written for health professionals.

The active ingredient in FIRDAPSE is amifampridine. Inactive ingredients are calcium stearate, colloidal silicon dioxide, and microcrystalline cellulose.

Please see full Prescribing Information for additional Important Safety Information.

What is FIRDAPSE®?

FIRDAPSE is a prescription medicine used to treat adults 17 years of age or older with Lambert-Eaton myasthenic syndrome (LEMS). The safety and efficacy of FIRDAPSE in patients under the age of 17 has not been established.

IMPORTANT SAFETY INFORMATION

What is the most important information I should know about FIRDAPSE?

  • FIRDAPSE can cause seizures.
    • You could have a seizure even if you never had a seizure before.
    • Do not take FIRDAPSE if you have ever had a seizure.

Stop taking FIRDAPSE and call your doctor right away if you have a seizure while taking FIRDAPSE.

Do not take FIRDAPSE if you:

  • have ever had a seizure
  • are allergic to amifampridine phosphate, or another aminopyridine.

Before you take FIRDAPSE, tell your doctor about all of your medical conditions, including if you:

  • are taking another aminopyridine, such as compounded 3,4-diaminopyridine (3,4-DAP)
  • have had a seizure
  • have kidney problems
  • have liver problems
  • are pregnant or plan to become pregnant. It is not known if FIRDAPSE will harm your unborn baby. You and your doctor will decide if you should take FIRDAPSE while you are pregnant.
  • are breastfeeding or plan to breastfeed. It is not known if FIRDAPSE passes into your breast milk. Talk to your doctor about the best way to feed your baby while taking FIRDAPSE.

Tell your doctor about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

How should I take FIRDAPSE?

  • Take FIRDAPSE exactly as your doctor tells you to take it. Do not change your dose of FIRDAPSE.
  • Do not take more than 2 tablets of FIRDAPSE at one time or more than 8 tablets of FIRDAPSE in a 24-hour period.
  • FIRDAPSE can be taken with or without food.
  • If you miss a dose of FIRDAPSE, skip that dose and take your next dose at your next scheduled dose time. Do not double your dose to make up the missed dose.
  • Do not take FIRDAPSE together with other medicines known to increase the risk of seizures.
  • If you take too much FIRDAPSE, call your doctor or go to the nearest hospital emergency room right away.

What are the possible side effects of FIRDAPSE?

FIRDAPSE may cause serious side effects, including:

  • Seizures. See "What is the most important information I should know about FIRDAPSE?"
  • Serious allergic reactions, such as anaphylaxis. FIRDAPSE can cause serious allergic reactions. Stop taking FIRDAPSE and call your doctor right away or get emergency medical help if you have:
    • shortness of breath or trouble breathing
    • swelling of your throat or tongue
    • ­hives
  • The most common side effects of FIRDAPSE include:
    • tingling around the mouth, tongue, face, fingers, toes, and other body parts
    • upper respiratory infection
    • stomach pain
    • nausea
    • diarrhea
    • headache
    • increased liver enzymes
    • back pain
    • high blood pressure
    • muscle spasms

Tell your doctor if you have any side effect that bothers you or that does not go away.

These are not all the possible side effects of FIRDAPSE.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

How should I store FIRDAPSE?

  • Store FIRDAPSE at 68ºF to 77ºF (20ºC to 25ºC).
  • Safely throw away FIRDAPSE that is out of date or no longer needed.

Keep FIRDAPSE and all medicines out of the reach of children.

If you would like more information, talk to your doctor or pharmacist. You can ask your pharmacist or doctor for additional information about FIRDAPSE that is written for health professionals.

The active ingredient in FIRDAPSE is amifampridine. Inactive ingredients are calcium stearate, colloidal silicon dioxide, and microcrystalline cellulose.

Please see full Prescribing Information for additional Important Safety Information.