Brain Activity and Ions
Epilepsy and bipolar disorder are two different diseases that are categorized by abnormal brain activity. Abnormal brain activity can be the result of unusual electrical activity. Nerve cells in the brain (also known as neurons) are electrically active. When a neuron gets stimulated, special channels get opened in the neuron that allow positively charged particles to flow into the cell. This causes a momentary positive electrical charge, which opens other channels in the neuron. When an electrical charge progresses from one end of the neuron to the other, it causes the release of special chemicals (called neurotransmitters) that can stimulate other nearby neurons. As a result, the electrical activity of just a few neurons can have a significant effect on many other neurons throughout the brain.
Lamotrigine and Sodium Channels
As Medline explains, lamotrigine is an anticonvulsant medication, which means that it works to prevent abnormal electrical activity in the brain. One of the main functions of lamotrigine is to block sodium channels in neurons. Sodium is a positively charged ion that is present in high concentrations outside of neurons. When sodium channels in a neuron open, sodium rushes in and causes a positive charge to occur in the neuron, which starts an electrical signal. Because lamotrigine blocks these channels, it works to prevent stimulation of neurons. Epilepsy is marked by abnormal neuronal electrical activity. Thus, by making it harder for neurons to get stimulated, lamotrigine works to relieve the symptoms of epilepsy.
An article in the Journal of Child Neurology notes that lamotrigine may have other ways in which it affects the brain. This is because lamotrigine is effective at treating many different kinds of seizures, unlike other sodium channel blockers (including carbamazepine and phenytoin). The fact that lamotrigine is more versatile than other sodium channel blockers hints that it has other effects on neurons and potentially blocks other kinds of channels. Regardless, lamotrigine's ability to inhibit electrical activity allows it to treat epilepsy as well as work as a mood stabilizer, which is useful for the treatment of bipolar disorder.