💊 Lamotrigine

Lamotrigine is an antiepileptic drug (AED) and a mood stabiliser, often used as an add-on therapy or monotherapy for various seizure types and in bipolar disorder.

Lamotrigine primarily stabilises neuronal membranes by blocking voltage-gated sodium channels, thereby inhibiting the release of excitatory neurotransmitters like glutamate and aspartate. It may also have some effects on voltage-gated calcium channels. This action reduces neuronal excitability and prevents the spread of seizure activity.

Lamotrigine is indicated for focal (partial) seizures and generalised tonic-clonic seizures, as well as seizures associated with Lennox-Gastaut syndrome. It is also a first-line treatment for the prevention of depressive episodes in patients with bipolar disorder, particularly bipolar II. It is generally well-tolerated in pregnancy compared to other AEDs.

Absolute contraindications are few, mainly hypersensitivity to lamotrigine. Caution is advised in patients with pre-existing cardiac conditions due to potential effects on cardiac conduction. It should be used with caution in patients with renal or hepatic impairment, requiring dose adjustments.

The most common adverse effects include rash (which can be severe), dizziness, headache, and nausea. Serious but rare adverse effects include Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), aseptic meningitis, and blood dyscrasias. The risk of severe rash is higher with rapid dose escalation or concomitant valproate.

Clinical monitoring for the appearance of rash is paramount, especially during the initial titration phase. Liver function tests (LFTs) and renal function should be monitored at baseline and if clinically indicated. Therapeutic drug monitoring is generally not routinely required but may be considered in specific circumstances.

Emphasise the slow titration schedule to minimise the risk of rash. Counsel patients to report any rash, fever, or flu-like symptoms immediately and to stop the medication if a severe rash develops. Advise on potential interactions, particularly with valproate which increases lamotrigine levels, and enzyme inducers which decrease them.

Lamotrigine is known for its slow titration to minimise the risk of severe rash (SJS/TEN). It's a good option for focal and generalised seizures, and particularly useful for bipolar depression. It has a relatively better safety profile in pregnancy compared to valproate. Remember the interaction with valproate, which inhibits its metabolism.

SBA questions frequently focus on the characteristic rash associated with lamotrigine, its potential severity (SJS/TEN), and the importance of slow dose titration. Scenarios might describe a patient developing a rash and ask about the appropriate management. Questions may also test knowledge of its use in bipolar depression or its relatively favourable pregnancy profile compared to other AEDs.