Why have I been prescribed this medication?

3,4-Diaminopyridine (3,4-DAP) is used in the treatment of Lambert-Eaton Myasthenic Syndrome (LEMS) and some congenital myasthenic syndromes (CMS). It is used to improve muscle strength.

How it works

Aminopyridines, such as 3,4-DAP, are types of medication that are able to block voltage-gated potassium channels. Potassium channels act as tunnels within our cells and allow the passage of potassium in and out. Potassium, and other elements in cells such as calcium, are responsible for a number of different roles, but in the case of myasthenia, the most important one is their ability to help nerves to function and muscles to contract.

In myasthenia, and specifically in the case of LEMS, the calcium channels in nerve cells are blocked, preventing passage of calcium, and reducing the amount of acetylcholine released in the space between nerve and muscle cells (a site called the neuromuscular junction). Without acetylcholine, muscles do not receive the message to contract and this can cause weakness at the joints. What 3,4-DAP does is to essentially extend the interval during which the calcium channel is open, and it does this by blocking the potassium channel.

How it is delivered

3,4-DAP is administered as a tablet. It can also be prepared as a suspension if you have difficulty swallowing if your dose is less than 5 mg.

When you have it and how long you will be taking it

3,4-DAP should be taken as and when your muscles will need it most. Your doctor may provide detailed instructions for when you should take it, and this should be followed. The length of time you will be taking 3,4-DAP for depends on your needs. Do not stop taking your medication unless your consultant neurologist tells you to, even if you feel unwell.

Side effects

All medicines can cause unwanted side effects, which usually improve as your body adjusts to the new medicine. 3,4-DAP is usually very well tolerated. In the early weeks of treatment, 3,4-DAP may cause tingling around the mouth and in the fingers and toes, but this usually disappears about an hour after taking the drug. Other side effects can include:

  • Diarrhoea
  • Blurred vision
  • Fatigue

Please check the patient information sheet supplied with your medication for a more detailed list of possible side effects. If any side effects disclosed concern you, seek reassurance from your doctor. If these symptoms persist, please contact your doctor. If you are worried about possible side effects and would like to talk to someone, you can also contact your doctor or the team at myaware who can help reassure you.

Known UK suppliers

Ascot Laboratories

FAQ (what else do I need to know?)

Before taking 3,4-DAP it is important to tell your doctor if you are pregnant or plan to become pregnant, as side effects for unborn babies is as yet unknown. This also applies if you are breastfeeding or planning to breastfeed.

Caution needs to be taken for people who have epilepsy and are being treated with 3,4-DAP. In addition, certain heart conditions can be affected by 3,4-DAP, and asthma can be exacerbated. If this concerns you, please discuss with your doctor the best route of treatment.