Amifampridine: uses, dosing, side effects & brands
Amifampridine is a medicine sold in the U.S. under one brand, for lambert-eaton myasthenic syndrome. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Treats
- Lambert-Eaton Myasthenic Syndrome
- Available as
- Tablet
- Sold as
- Firdapse
- Prescription?
- Prescription only
- Generic available?
- Not in our catalog
How amifampridine is dosed
From the FDA label for Firdapse (application NDA208078). Other amifampridine products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
Administer orally in divided doses (3 to 5 times daily). ( 2.1 ) The recommended starting dosage for adults (any weight) and pediatric patients weighing 45 kg or more is 15 mg to 30 mg daily, in divided doses. ( 2.1 ) Dosage can be increased by 5 mg daily every 3 to 4 days. ( 2.1 ) The maximum single dose is 20 mg. ( 2.1 ) Dosage is not to exceed a maximum of 100 mg daily. ( 2.1 ) The recommended starting dosage for pediatric patients weighing less than 45 kg is 5 mg to 15 mg daily, in divided doses. ( 2.1 ) Dosage can be increased by 2.5 mg daily every 3 to 4 days. ( 2.1 ) The maximum single dose is 10 mg. ( 2.1 ) Dosage is not to exceed a maximum of 50 mg daily. ( 2.1 ) The recommended starting dosage for adult and pediatric patients with renal impairment, hepatic impairment, and in known N-acetyltransferase 2 (NAT2) poor metabolizers is the lowest recommended initial daily dosage ( 2.1 , 2.2 , 2.3 , 2.4 ) For patients with a dosage adjustment of less than 5 mg increments, or who have difficulty swallowing, or require feeding tube, a l mg/mL suspension can be prepared. ( 2.5 ) 2.1 Dosage Information The recommended oral dosage of FIRDAPSE for adults and pediatric patients 6 years of age and older is included in Table 1 . For pediatric patients, the recommended dosing regimen is dependent on body weight. Dosage should be increased every 3 to 4 days based on clinical response…
Amifampridine side effects
The following serious adverse reactions are described elsewhere in the labeling: Seizures [see Warnings and Precautions ( 5.1 )] Hypersensitivity [see Warnings and Precautions ( 5.2 )] 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. ( 6 ) 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 . 6.1 Clinical Trials Experience Adults Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. In controlled and uncontrolled clinical trials (Study 1 and 2) in patients with LEMS [see Clinical Studies ( 14 )] , 63 patients were treated with FIRDAPSE, including 40 patients treated for more than 6 months, and 39 patients treated for more than 12 months. In an expanded access program, 139 patients with LEMS were treated with FIRDAPSE, including 102 patients treated for more than 6 months, 77 patients treated for more than 12 months, and 53 patients treated for more than 18 months. In the expanded access program, patients were…
Who shouldn’t take amifampridine
FIRDAPSE is contraindicated in patients with: A history of seizures [see Warnings and Precautions ( 5.1 )] Hypersensitivity to amifampridine phosphate or another aminopyridine [see Warnings and Precautions ( 5.2 )] FIRDAPSE is contraindicated in patients with: A history of seizures ( 4 ) Hypersensitivity to amifampridine or another aminopyridine ( 4 )
Amifampridine drug interactions
Drugs that lower seizure threshold: Concomitant use may lead to an increased risk of seizures. ( 7.1 ) Drugs with cholinergic effects (e.g., direct or indirect cholinesterase inhibitors): Concomitant use may increase the cholinergic effects of FIRDAPSE and of those drugs and increase the risk of adverse reactions. ( 7.2 ) 7.1 Drugs that Lower Seizure Threshold The concomitant use of FIRDAPSE and drugs that lower seizure threshold may lead to an increased risk of seizures [see Warnings and Precautions ( 5.1 )]. 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. 7.2 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.
Every amifampridine product we track (1)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
Only one: Firdapse.
What amifampridine pills look like
Imprint codes, colour and shape from the FDA’s labelling data. Match the imprint on your pill — or search any imprint.
| Imprint | Strength | Colour | Shape | Maker |
|---|---|---|---|---|
| CATALYST;211;10 | 10 mg | white | round | — |
Can you crush or split amifampridine?
The amifampridine labels that address it permit crushing or splitting in the terms they state — quoted per product, because the instruction belongs to the form.
What each amifampridine label says about crushing, splitting and chewingWhat people report to the FDA about amifampridine
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 6 reports naming amifampridine, and the FDA flagged 100% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- asthenia3 reports
- diverticulitis3 reports
- dyspnoea3 reports
- abdominal abscess2 reports
- abdominal pain upper2 reports
- anaemia2 reports
- constipation2 reports
- deep vein thrombosis2 reports
Read these as a signal, not a rate. A report does not mean amifampridine caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.
Source: openFDA drug/event (FAERS), retrieved July 25, 2026.
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Frequently asked questions
What is amifampridine?
Firdapse (Amifampridine Phosphate) is a medication used to treat Lambert-Eaton Myasthenic Syndrome.
Can you take amifampridine with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run amifampridine against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What forms does amifampridine come in?
Across the brands we track, amifampridine is currently marketed as tablet, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic amifampridine?
We do not currently list a generic-labelled amifampridine product. That does not always mean none exists — it means none appears under a generic name in the FDA data we track. Ask your pharmacist.
Cite this page
- APA
- pharmaranks. (2026, July 24). Amifampridine: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/amifampridine
- MLA
- “Amifampridine: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/amifampridine.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for amifampridine on DailyMed (NIH) ↗.