Firdapse (amifampridine) is the first FDA-approved medication to treat Lambert-Eaton myasthenic syndrome (LEMS), a rare, autoimmune condition that can cause muscle weakness. The medication can cause seizures as well as many other side effects.
Lambert-Eaton myasthenic syndrome (LEMS)
Firdapse (amifampridine) is a potassium channel blocker. It's not exactly known how this medication works to treat LEMS, but it's thought to target your muscles' nerve junctions to help with nerve signaling.
Source: DailyMed
Side effects that you should report to your care team as soon as possible:
Side effects that usually do not require medical attention (report these to your care team if they continue or are bothersome):
Works well to treat symptoms of LEMS (e.g., muscle strength, function, and mobility)
Can be taken with or without food
Can be used in pregnancy, if needed
Needs to be taken 3 to 4 times per day
Brand-name only, which can be expensive
Can't be used in children younger than 18 years old
Make sure to tell your provider about all the medications you're taking before starting Firdapse (amifampridine), especially if you take medications that raise your risk for seizures or cholinesterase inhibitors. These particular medications can raise your risk of seizures and other side effects from Firdapse (amifampridine). Don't start any new medications while taking Firdapse (amifampridine) without talking to your provider or pharmacist first.
Take Firdapse (amifampridine) with or without food.
If you forget to take Firdapse (amifampridine), skip the missed dose and take your usual dose at the next scheduled time. Don't double your dose or take extra doses to make up for the missed dose.
Read the medication guide for more information on Firdapse (amifampridine).
Firdapse (amifampridine) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Risk factors: History of seizures | Have medical conditions or take medications that raise the risk of seizures
Firdapse (amifampridine) can cause seizures. They can happen in people taking this medication at recommended doses who haven't had a seizure before and can happen at any time during treatment. But your risk is higher if you have medical conditions or take medications that raise your risk for seizures. If you have a seizure or any symptoms of a seizure while taking Firdapse (amifampridine), contact your provider.
The typical starting daily dose is 15 mg to 30 mg by mouth per day, divided into 3 to 4 doses throughout the day. The maximum single dose is 20 mg (or 2 tablets), and the maximum total daily dose is 80 mg (or 8 tablets).
Your provider will change your dose based on if you're having side effects and if it's helping your condition. Your dose might differ if you have kidney or liver problems. It might also differ if your body is unable to break down the medication well (based on genetic testing).
History of seizures
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