A tablet for Lambert-Eaton myasthenic syndrome
Amifampridine
A specialist tablet used to improve muscle strength in Lambert-Eaton myasthenic syndrome.
What is Amifampridine?
Amifampridine is a specialist medicine used to treat Lambert-Eaton myasthenic syndrome, a rare condition where the nerves cannot pass signals to the muscles properly, causing weakness. It works by helping nerves release more of the chemical that tells muscles to contract, improving strength. It is taken by mouth, spread through the day. A common, harmless effect is tingling around the mouth and in the fingers. Its most important risk is that it can lower the threshold for seizures, so it is used with care, especially in people prone to fits.
Education and reference only. This is a plain-language guide to Amifampridine — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Amifampridine is a medicine used to treat the muscle weakness of Lambert-Eaton myasthenic syndrome, a rare condition in which the body's immune system disrupts the way nerves signal to muscles. As a result, muscles tire and weaken, often affecting the legs and the ability to walk. Amifampridine helps restore some of that nerve-to-muscle signalling, improving strength and stamina. It is taken by mouth, usually in several small doses through the day, and is prescribed and supervised by a specialist neurology team.
How it works
In Lambert-Eaton myasthenic syndrome, nerve endings release too little of a chemical messenger called acetylcholine, which is needed to tell muscles to contract. Amifampridine blocks tiny channels (potassium channels) in the nerve endings, which keeps the nerve active for longer and prompts it to release more acetylcholine. With more of this messenger reaching the muscle, the muscle contracts more strongly, improving weakness. Because the effect lasts only while the medicine is in the body, it is taken several times a day, and the dose is built up gradually to find the right balance.
Company & origin
Originated / developed by: Specialist manufacturer.
A specialist medicine used in the UK to treat the muscle weakness of Lambert-Eaton myasthenic syndrome.
Practical use
How to take Amifampridine
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it by mouth as prescribed, usually in several small doses spread through the day.
- Build up the dose gradually exactly as your specialist directs, rather than increasing it on your own.
- Do not be alarmed by tingling around the mouth or in the fingers, which is common and usually harmless.
- Tell your team about any history of fits or heart-rhythm problems before starting.
- Keep to the timing of your doses, as the effect wears off between them.
Weighing it up
Advantages & disadvantages of Amifampridine
Advantages
- Improves muscle strength and stamina in Lambert-Eaton myasthenic syndrome.
- Taken by mouth as tablets.
- Can make a meaningful difference to walking and daily activities.
Disadvantages
- Can lower the seizure threshold, so it is used with care in people prone to fits.
- Commonly causes tingling around the mouth and in the hands and feet.
- Needs to be taken several times a day and built up gradually.
Practical use
Good to know
A very common and harmless effect of amifampridine is tingling or pins-and-needles, especially around the mouth and in the fingers and toes; this often eases and is usually a sign the medicine is working rather than something to worry about. The most important safety point is that it can make seizures (fits) more likely by lowering the seizure threshold, so it is used with extra care in anyone with epilepsy or a history of fits, and the dose is built up slowly. It can also occasionally affect the heart's electrical rhythm, so the team may check this, particularly if other medicines are involved. Doses are spread through the day and the timing matters, so keeping to the schedule helps. The specialist team adjusts the dose to get the best improvement in strength with the fewest side effects.
Who should not take it / use with caution
- People who have had a serious allergic reaction to amifampridine should not take it.
- It is not suitable for people with epilepsy or seizures that are not well controlled.
- It is used with care in people with certain heart-rhythm problems or those taking medicines that affect the heart rhythm.
- It should only be used under specialist neurology care, with the dose built up gradually.
Monitoring
- Reviewing how much muscle strength and stamina improve.
- Watching for any seizures, especially as the dose is increased.
- Checking the heart's rhythm where appropriate, particularly with other relevant medicines.
Side effects
- Tingling or pins-and-needles around the mouth and in the fingers and toes, which is common.
- Stomach upset, such as nausea or tummy pain.
- A lowering of the seizure threshold, making fits more likely at higher doses.
- Occasionally, changes in the heart's electrical rhythm.
Key interactions
- Care is needed with other medicines that can lower the seizure threshold or that affect the heart rhythm.
- Tell your team about all your medicines, as some can interact with amifampridine.
- Other treatments for the condition may be used alongside it under specialist guidance.
Available as: Tablets taken by mouth.
Answers
Amifampridine: frequently asked questions
What is amifampridine used for?
It is used to treat the muscle weakness of Lambert-Eaton myasthenic syndrome, a rare condition where nerves cannot signal properly to the muscles.
Why do I get tingling around my mouth?
Tingling or pins-and-needles around the mouth, fingers and toes is a common and usually harmless effect that often eases with time.
Can it cause fits?
It can make seizures more likely by lowering the seizure threshold, especially at higher doses, so it is used with care in anyone prone to fits and built up slowly.
Why do I take it several times a day?
Its effect wears off between doses, so it is spread through the day to keep your muscle strength more even.
How is the right dose found?
The dose is built up gradually under your specialist's guidance to get the best improvement in strength with the fewest side effects.
Authoritative sources
- BNF
- NICE CKS
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