Generic drug: amifampridine
Brand name: Firdapse
What is Firdapse (amifampridine), and how does it work?
Firdapse is a prescription medicine used to treat Lambert-Eaton myasthenic syndrome (LEMS), an autoimmune disease, in adults.
It is not known if Firdapse is safe or effective in children.
What are the side effects of Firdapse?
Firdapse may cause serious side effects, including:
- Seizures.
- 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 FDAat 1-800-FDA-1088.
What is the dosage for Firdapse?
- The recommended starting dosage of Firdapse is 15 mg to 30 mg daily, taken orally in divided doses (3 to 4 times daily).
- The dosage canbe increased by 5 mg daily every 3 or 4days.
- The maximum recommended total daily dosage is 80 mg.
- The maximum single dose is 20 mg.
- If a dose is missed, patients should not take double or extra doses.
Patients With Renal Impairment
- The recommended starting dosage of Firdapse in patients with renal impairment (creatinine clearance 15 to 90 mL/min) is 15 mg daily, taken orally in 3 divided doses. No dosage recommendation for Firdapse can be made for patients with end-stage renal disease.
Patients With Hepatic Impairment
- The recommended starting dosage of Firdapse in patients with any degree of hepatic impairment is 15 mg daily, taken orally in 3 divided doses.
Known N-acetyltransferase 2 (NAT2) Poor Metabolizers
- The recommended starting dosage of Firdapse in known N-acetyltransferase 2 (NAT2) poor metabolizers is 15 mg daily, taken orally in 3 divided doses.
Administration Instructions
- Firdapse can be taken without regard to food.
What drugs interact with Firdapse?
Drugs That Lower Seizure Threshold
The concomitant use of Firdapse and drugs that lower seizure threshold may lead to an increased risk of seizures. The decision to administer Firdapse concomitantly with drugs that lower the seizure threshold should be carefully considered in light of the severity of the associated risks.
Drugs With Cholinergic Effects
The concomitant use of Firdapse and drugs with cholinergic effects (e.g., direct or indirect cholinesterase inhibitors) may increase the cholinergic effects of Firdapse and of those drugs and increase the risk of adverse reactions.
Is Firdapse safe to use while pregnant or breastfeeding?
- There are no data on the developmental risk associated with the use of Firdapse in pregnant women.
- There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to Firdapse during pregnancy. Physicians are encouraged to enroll pregnant patients, or pregnant women may register themselves in the registry by calling 855-212-5856 (toll-free), using the Fax number 877-867-1874 (toll-free), by contacting the Pregnancy Coordinating Center at [email protected], or by visiting the study website www.firdapsepregnancystudy.com
- There are no data on the presence of Firdapse in human milk, the effects on the breastfed infant, or the effects on milk production.
- The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for Firdapse and any potential adverse effects on the breastfed infant from Firdapse or from the underlying maternal condition.

QUESTION
Lupus is an infection. See AnswerSummary
Firdapse is a prescription medicine used to treat Lambert-Eaton myasthenic syndrome (LEMS), an autoimmune disease, in adults. It is not known if Firdapse is safe or effective in children. Serious side effects of Firdapse include seizures and serious allergic reactions (anaphylaxis).
Multimedia: Slideshows, Images & Quizzes
-
16 Foods That Boost and Improve Your Immune System
Help fight colds, flu, as well as viruses like coronavirus with foods that boost and improve your immune system. Reach for...
-
Top 15 Immune System Boosters
Immune system boosters include foods, supplements, and lifestyle habits to help you fight off infections. A healthy immune system...
-
Cold, Flu, and Cough: Things That Suppress Your Immune System
A strong immune system is your best protection against infections and illnesses. Find out what can weaken that defense.
-
How Your Immune System Functions
What is the immune system and its function? Your immune system finds and kills germ invaders when you are sick from a cold, the...
Related Disease Conditions
-
Is Dermatographia an Autoimmune Disease?
The exact cause of dermatographia is unknown. However, it appears to be an autoimmune disease in nature because autoantibodies to certain skin proteins have been found in some patients. Dermatographia can be linked to the inappropriate release of the chemical histamines.
-
Primary Immunodeficiency Disease (PIDD)
Primary immunodeficiency disease or PIDD is a group of over 250 genetic diseases that involve the immune system. Symptoms of primary immunodeficiency diseases depend upon the specific disease, but some may include: Enlarged spleen Abnormal blood counts Recurrent skin infections Digestive problems Frequent hard-to-treat infections Treatment for primary immunodeficiency disease depend upon the cause.
-
What Are the Different Autoimmune Disorders?
An autoimmune disorder occurs when a person’s immune system mistakenly attacks their own body tissues such as the skin or joints considering them as foreign.
Treatment & Diagnosis
Medications & Supplements
Prevention & Wellness
Health News
- Weed-Friendly Posts on Social Media Get Teens Using Cannabis
- Deer Carry COVID Variants No Longer Seen in People
- Working Gets Tough When Grieving a Lost Spouse
- Obamacare Helped Women in Some Southern States Get Better Breast Cancer Care
- AHA News: Pregnancy Complications Could Increase Woman's Stroke Risk at Earlier Age
More Health News »
Health Solutions From Our Sponsors

Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.