Lamotrigine

💊 What is Lamotrigine used for?

• •Epilepsy, as add-on (adjunctive) treatment in people aged 2 years and older for partial-onset seizures, primary generalized tonic-clonic (PGTC) seizures, and generalized seizures of Lennox-Gastaut syndrome
• •Epilepsy, as a single medicine (monotherapy) in adults aged 16 years and older with partial-onset seizures who are switching from carbamazepine, phenytoin, phenobarbital, primidone, or valproate given as their only anti-epileptic drug
• •Maintenance treatment of bipolar I disorder, to delay the time until new mood episodes (depression, mania, hypomania, or mixed episodes) in people who were treated for an acute mood episode with standard therapy

How it works

How it is usually taken

• •The label describes lamotrigine as a tablet taken by mouth. The label says dosing depends on other medicines being taken, the condition being treated, and the person's age, and that the dose is changed in steps over time. The label also notes that the recommended starting dose and the steps for increasing the dose should not be exceeded, because this raises the risk of rash. Follow the instructions from your prescriber or pharmacist. Do not stop the medicine suddenly. The label says tapering over at least 2 weeks is recommended when stopping.

Comes as

• •25 mg orally disintegrating tablets: white, round, flat-faced, bevel-edged, marked "NT" on one side and "123" on the other
• •50 mg orally disintegrating tablets: white, round, flat-faced, bevel-edged, marked "EP" on one side and "191" on the other
• •100 mg orally disintegrating tablets: peach, round, flat-faced, bevel-edged, marked "E" on one side and "432" on the other
• •200 mg orally disintegrating tablets: white, round, flat-faced, bevel-edged, marked "EP" on one side and "433" on the other

⚠️ Lamotrigine side effects

🛑 Who should not take Lamotrigine, and who should be careful

The label says not to take it if

• 🚨You have had a hypersensitivity reaction to lamotrigine or any of its ingredients. The label lists examples as rash, swelling under the skin (angioedema), acute hives (urticaria), extensive itching, or mouth or other mucosal ulcers.

Tell your doctor before taking it if

• •Tell your healthcare provider about all of your health conditions, especially any heart problems.
• •Tell your provider if you have ever had an allergy or rash to other anti-epileptic drugs. The label says this can increase the risk of non-serious rash.
• •Tell your provider if you take valproate (valproic acid or divalproex sodium). The label says this raises the risk of serious rash.
• •Tell your provider if you take estrogen-containing products, including birth control pills. The label says doses often need to be adjusted when these are started or stopped.
• •The label says that people of Asian origin, mainly Han Chinese and Thai, may carry an HLA-B*1502 gene variant linked to serious skin reactions. Tell your provider about your background and any family history of serious skin reactions.
• •The label says that suicidal thoughts can come from causes other than medicines. Your provider may check for other causes if these symptoms appear.
• •The label says the medicine has names similar to other medicines. Check each prescription you receive against the tablet pictures in the Medication Guide, and ask your pharmacist to confirm it is the correct medicine.

🔀 Lamotrigine with other medicines, food and alcohol

The label says to discuss these with your doctor or pharmacist

• •Estrogen-containing oral contraceptives (the label mentions a product with 30 mcg ethinylestradiol and 150 mcg levonorgestrel): these can lower lamotrigine levels by about 50%.
• •Valproate: can raise lamotrigine levels to slightly more than twice the usual amount, and raises the risk of serious rash.
• •Carbamazepine: can lower lamotrigine levels by about 40%.
• •Phenytoin, phenobarbital, or primidone: can lower lamotrigine levels by about 40%.
• •Lopinavir/ritonavir: can lower lamotrigine levels by about 50%.
• •Atazanavir/ritonavir: can lower lamotrigine exposure by about 32%.
• •Rifampin: can lower lamotrigine exposure by about 40%.
• •Other strong or moderate enzyme inducers (CYP3A4): may speed up how the body clears lamotrigine. The label says doses may need adjusting for these medicines.

Alcohol and food

The label does not say.

🤰 Lamotrigine in pregnancy and breastfeeding

Pregnancy

The label says there is a pregnancy exposure registry for women taking anti-epileptic drugs, including lamotrigine, and encourages women who take lamotrigine during pregnancy to enroll (North American Antiepileptic Drug Pregnancy Registry, 1-888-233-2334). The label says registry and epidemiological studies have not found an increased frequency of major birth defects or a consistent pattern of birth defects compared with the general population. The label notes that most of this data comes from women with epilepsy. In animal studies, lamotrigine caused developmental toxicity at doses lower than those used clinically, and it lowered fetal folate levels in rats.

Breastfeeding

The label does not say.

🗓️ Storage, missed doses and taking too much

Storage

The label says to store the tablets at 20° to 25°C (68° to 77°F).

If a dose is missed

The label does not say.

If too much is taken

The label says overdoses of up to 15 grams have been reported, and some were fatal. Overdose can cause unsteady movement (ataxia), abnormal eye movements (nystagmus), seizures including tonic-clonic seizures, decreased consciousness, coma, and a heart conduction delay. There is no specific antidote. The label says hospitalization is advised after a suspected overdose, with general supportive care and close monitoring.

🗒️ Questions to ask about Lamotrigine

• Which of the rash warning signs should I watch for, and how quickly should I contact you if one appears?
• Am I at higher risk of serious rash because I take valproate, or because of my genetic background?
• Does my birth control pill or other estrogen product affect my lamotrigine dose?
• What should I do if I miss a dose, and how should I stop this medicine safely if needed?
• Which other medicines I take could lower or raise my lamotrigine levels?
• How will you check for mood changes, suicidal thoughts, or heart symptoms while I take this medicine?

❓ Lamotrigine: frequently asked questions