How does lamotrigine work?
Lamotrigine is a type of anticonvulsant drug that acts by blocking sodium channels, reducing the amount of sodium released by nerves as they transmit messages to and from the brain. This can reduce or block some messages and thus reduce the sensation of pain.
Inflammation in the central nervous system leads to increased levels of nitric oxide and sodium, both of which can damage nerve cells. Lamotrigine's role in regulating the chemical processes within nerves has led to it being studied to see if it has a neuroprotective effect.
How do I take lamotrigine?
Lamotrigine is taken orally as tablets for the treatment of pain. Experimental doses range from 25–400mg per day. People start on a low dose that is gradually increased.
Side effects and contraindications
Side effects include rash, headache, stomach upsets, double vision, dizziness and ataxia (problems with coordination). Lamotrigine can stop some types of oral contraceptive pill from working, so this should be taken into account.
Lamotrigine has been studied to see if it can help stop damage to nerve cells and therefore prevent the further accumulation of disability – an approach known as neuroprotection.
In one phase II study, 120 people with secondary progressive MS received lamotrigine or placebo for two years. The trial measured the rate of change in the volume of the central area of the brain (known as the partial cerebral volume). In the first year, lamotrigine treatment appeared to be associated with greater volume loss than placebo. This loss reversed partially on discontinuation of treatment. Over the full 24 months of the trial, the effect of lamotrigine on cerebral volume did not differ from that of placebo. People in the lamotrigine group showed a slower deterioration of the timed 25-foot walk test, but other measures showed no difference with the placebo group.
Another phase II study of the neuroprotective effects of lamotrigine in combination with interferon beta 1a (Avonex) in people with relapsing remitting MS took place in Switzerland but is still to report any results.
- London: NICE; 2013. Full guideline Neuropathic pain: pharmacological management.
- Clinical Therapeutics 2007;29(9):2022–2030. Summary A randomized, double-blind, placebo-controlled, two-period, crossover, pilot trial of lamotrigine in patients with central pain due to multiple sclerosis.
- Lancet Neurology 2010;9(7):681–688. Summary Lamotrigine for neuroprotection in secondary progressive multiple sclerosis: a randomised, double-blind, placebo-controlled, parallel-group trial.