Lamotrigine

How it works

It stabilises neuronal membranes by inhibiting voltage-gated sodium channels, reducing the release of excitatory neurotransmitters such as glutamate.

Prescribing in practice

• The most important paediatric concern is the risk of serious, potentially life-threatening skin reactions (including Stevens-Johnson syndrome and toxic epidermal necrolysis), which is higher in children and is strongly linked to rapid dose escalation and concomitant valproate, so titration must be slow and any rash assessed urgently.
• Initial doses and titration schedules differ substantially depending on whether the child also takes valproate (which raises lamotrigine levels) or enzyme-inducing antiepileptics; always confirm against a children's formulary.
• Withdrawal should be gradual to avoid rebound seizures, and parents should not stop the drug abruptly.

Monitoring

Monitor for rash and hypersensitivity (especially in the first weeks), seizure control and behavioural changes; routine plasma-level monitoring is not generally required but may help in specific situations.

Counselling the patient

• Seek urgent medical advice for any rash, mouth ulcers, fever, blistering or facial swelling, particularly in the first eight weeks.
• Do not stop the medicine suddenly, and give it at the same times each day.
• Tell the prescriber about any change in other medicines, as this can affect lamotrigine levels.

Evidence & guidelines

MHRA guidance highlights the dose-related risk of serious skin reactions with lamotrigine, and its paediatric use is supported by NICE epilepsy guidance.