The brain and nerves are made up of many nerve cells that communicate with each other through electrical signals. These signals must be carefully regulated for the brain and nerves to function properly. When abnormally rapid and repetitive electrical signals are released in the brain, the brain becomes over-stimulated and normal function is disturbed. This results in fits or seizures.
Lamotrigine prevents epileptic fits by preventing excessive electrical activity in the brain. It does this by preventing sodium from entering nerve cells when they begin to fire rapid and repetitive electrical signals. A build up of sodium in the nerve cells is necessary for the electrical signal to build up and be passed on to other nerve cells. As lamotrigine prevents this, it helps stabilise the electrical activity in the brain.
Preventing the build-up of the electrical signal also prevents the release of a neurotransmitter called glutamate from the nerve cells in the brain. Neurotransmitters are chemicals that are stored in nerve cells and are involved in transmitting messages between the nerve cells. Glutamate is a neurotransmitter that acts as a natural 'nerve-exciting' agent. It is released when electrical signals build up in nerve cells and subsequently excites more nerve cells. It is thought to play a key role in causing epileptic seizures. Reducing the release of glutamate from the nerve cells in the brain is another way in which lamotrigine helps stabilise the electrical activity in the brain and prevent epileptic fits.
In addition to its licensed use for treating epilepsy, lamotrigine is used off-licence by specialists as a mood stabiliser for treating people with the psychiatric illness, bipolar affective disorder. This use is not licensed, but the medicine has been shown to be effective in people with bipolar disorder who have not responded to the traditional mood stabilisers (lithium, carbamazepine, valproate). Lamotrigine is used for treating episodes of high or low mood and for helping to prevent episodes of ill health in these people. It is not fully understood how lamotrigine works in this illness, but is thought to be to do with the reduction of glutamate in the brain.
A further unlicensed use of lamotrigine is in the treatment of a condition called trigeminal neuralgia, in which the facial nerves spontaneously send messages of pain to the brain. As lamotrigine stabilises electrical nerve activity, it prevents the nerve signals being sent inappropriately and relieves the pain of this condition.
Lamictal tablets should be swallowed whole with a drink of water. Lamictal dispersible tablets may be chewed, dispersed in a small volume of water (at least enough to cover the whole tablet) or swallowed whole with a little water.
