1. Introduction
Lamotrigine is an antiepileptic medication (AED) and mood stabiliser primarily used to manage epilepsy and bipolar disorder. It works by inhibiting voltage-sensitive sodium channels, stabilising neuronal membranes, and reducing excessive neuronal firing.
2. Indications
- Approved Indications:
- Epilepsy:
- Focal (partial) seizures.
- Generalised tonic-clonic seizures.
- Lennox-Gastaut syndrome (adjunctive therapy).
- Bipolar disorder: Maintenance treatment to prevent depressive episodes.
- Epilepsy:
- Off-Label Uses:
- Trigeminal neuralgia.
- Neuropathic pain.
- Borderline personality disorder (symptom management).
3. Dosage
- Epilepsy:
- Adults and Children (≥12 years):
- Initial: 25 mg once daily for 2 weeks, then 50 mg daily for 2 weeks, followed by dose escalation based on clinical response.
- Maintenance: 100–400 mg daily, in one or two divided doses.
- Children (2–12 years):
- Dose depends on weight and whether adjunctive therapy is used. Typically 0.3 mg/kg/day initially, titrated to 1–15 mg/kg/day.
- Adults and Children (≥12 years):
- Bipolar Disorder:
- Adults:
- Initial: 25 mg once daily for 2 weeks, then 50 mg daily for 2 weeks, followed by titration to 100–200 mg daily.
- Elderly:
- Start with lower doses and titrate slowly.
- Adults:
- Dose Adjustments:
- Reduced dose required if taken with valproate (due to interaction).
- Increased dose needed with enzyme inducers (e.g., carbamazepine, phenytoin).
4. Administration
- Take orally, with or without food.
- Tablets should be swallowed whole or chewed (if chewable formulation is used).
- Consistency with timing is essential to maintain stable blood levels.
5. Forms Available
- Tablets: 25 mg, 50 mg, 100 mg, 200 mg.
- Dispersible/chewable tablets: 2 mg, 5 mg, 25 mg.
6. Side Effects
6.1. Common Side Effects
- Dizziness.
- Headache.
- Nausea or vomiting.
- Insomnia.
6.2. Less Common Side Effects
- Blurred vision or diplopia.
- Skin rash (mild).
- Tremors.
6.3. Rare but Serious Side Effects
- Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN).
- Aseptic meningitis.
- Severe hypersensitivity reactions (e.g., drug reaction with eosinophilia and systemic symptoms – DRESS).
- Suicidal ideation.
7. Warnings
- Skin Reactions: Risk of severe rashes (e.g., SJS/TEN) is higher with rapid dose escalation or use in children. Discontinue if rash appears.
- Suicidality: Monitor for suicidal thoughts or behaviours in patients.
- Valproate Interaction: Increases lamotrigine levels significantly, requiring dose adjustments.
8. Precautions
- Use cautiously in patients with:
- Hepatic impairment.
- Renal impairment.
- Depression or psychiatric conditions (monitor for mood changes).
- Avoid abrupt discontinuation to prevent rebound seizures or mood destabilisation.
9. Interactions
- Drug-Drug Interactions:
- Valproate: Increases lamotrigine levels (reduce dose).
- Enzyme inducers (e.g., carbamazepine, phenytoin): Decrease lamotrigine levels (increase dose).
- Hormonal contraceptives: Reduce lamotrigine levels; additional dose adjustments may be needed.
- Drug-Food Interactions:
- None significant.
10. Monitoring Parameters
- Seizure frequency and severity (for epilepsy).
- Mood stability (for bipolar disorder).
- Skin examination for rashes.
- Liver function tests (in patients with hepatic impairment).
11. Use in Children
- Approved for epilepsy in children ≥2 years and for bipolar disorder in children ≥18 years. Dose adjustments are weight-based.
12. Use in Pregnancy
- Category C: Can be used if benefits outweigh risks. Lamotrigine levels decrease during pregnancy due to increased clearance, so dose adjustments may be needed.
- Monitor for congenital malformations (low risk).
13. Use in Elderly
- Safe for elderly patients but requires cautious dose titration due to slower drug clearance.
14. Use in Kidney Disease
- Dose adjustments may be required in moderate to severe renal impairment due to altered clearance of the drug and its metabolites.
15. Use in Liver Disease
- Use cautiously in mild to moderate hepatic impairment. Reduce the maintenance dose by 50%–75% in severe hepatic impairment.
16. Patient Counselling Points
- Take lamotrigine exactly as prescribed and do not miss doses.
- Report any skin rash, fever, or flu-like symptoms immediately, as these may indicate a serious reaction.
- Do not stop taking lamotrigine suddenly; taper the dose as advised by your doctor.
- Inform your doctor if you become pregnant, as dose adjustments may be required.
- If using hormonal contraceptives, discuss potential dose changes with your doctor.
- Avoid activities requiring alertness (e.g., driving) if you experience dizziness or drowsiness.
17. Table of Brand Names, Manufacturers, and Prices
Brand Name | Manufacturer | Price (USD) |
---|---|---|
Lamictal | GSK | $100–150 (30 tablets, 100 mg) |
Generic Lamotrigine | Various manufacturers | $15–50 (30 tablets, 100 mg) |
18. FAQs (15 Questions)
- What is lamotrigine used for?
It is used to treat epilepsy and as a mood stabiliser in bipolar disorder. - How does lamotrigine work?
It reduces excessive neuronal firing by inhibiting sodium channels, stabilising brain activity. - How long does it take for lamotrigine to work?
Effects on mood may take several weeks. Seizure control usually improves within days to weeks. - Can lamotrigine cause side effects?
Yes, common side effects include dizziness, headache, and nausea. Rarely, it may cause severe skin reactions. - What is the most serious side effect of lamotrigine?
Severe skin reactions such as Stevens-Johnson syndrome or toxic epidermal necrolysis. - How should lamotrigine be taken?
Take it orally, with or without food, at the same time each day. - What should I do if I miss a dose?
Take it as soon as you remember, but skip it if it’s close to the next dose. Do not double the dose. - Can lamotrigine be used during pregnancy?
Yes, but dose adjustments are often needed due to changes in drug clearance. - Does lamotrigine interact with hormonal contraceptives?
Yes, contraceptives can lower lamotrigine levels, potentially requiring dose adjustments. - Can I stop lamotrigine suddenly?
No, sudden discontinuation can cause withdrawal seizures or mood destabilisation. - Is lamotrigine safe for children?
Yes, it is approved for epilepsy in children ≥2 years and for bipolar disorder in those ≥18 years. - Can lamotrigine cause weight gain?
Weight gain is uncommon. Some people may even experience mild weight loss. - How should lamotrigine be stored?
Store at room temperature, away from moisture and heat. - Can lamotrigine cause drowsiness?
Yes, drowsiness is a possible side effect, especially when starting treatment. - Can lamotrigine be taken with other epilepsy medications?
Yes, but dose adjustments may be required due to interactions with other antiepileptic drugs.