Indications/Uses

Monotherapy and adjunctive treatment of partial seizures and primary and secondary generalized tonic-clonic seizures, seizures associated with Lennox-Gastaut syndrome. It is also used in the prophylaxis of bipolar disorder in adults.

Dosage/Direction for Use

For Epilepsy: Monotherapy in adults and children >12 years: Initial adult dose as monotherapy is 25 mg once daily by mouth for 2 weeks followed by 50 mg once daily for 2 weeks; thereafter the dose is increased by a maximum of 50 to 100 mg every 1 to 2 weeks to usual maintenance doses of 100 to 200 mg daily, given as a single dose or in 2 divided doses. Some patients have required up to 500mg daily.
Add on therapy (without valproate): Adults: 50 mg once daily for 2 weeks followed by 50 mg twice daily for 2 weeks, thereafter the dose is increased by a maximum of 100 mg every 1 to 2 weeks to usual maintenance doses of 200 to 400 mg daily given in 2 divided doses. Some patients have required up to 700 mg daily.
Children 2 to 12 years: Initial dose is 600 mcg/kg body weight daily in 2 divided doses for 2 weeks followed by 1.2 mg/kg body weight in two divided doses for 2 weeks; thereafter the dose is increased by a maximum of 1.2 mg/kg body weight every 1 to 2 weeks to a usual maintenance dose of 5 to 15 mg/kg body weight given in 2 divided doses. Add on therapy (with valproate): Adults: Initial dose is 25 mg every other day for 2 weeks followed by 25 mg once daily for 2 weeks; thereafter the dose is increased by a maximum of 25 to 50 mg every 1 to 2 weeks to usual maintenance doses of 100 to 200 mg daily given as a single dose or in 2 divided doses.
Children: Initial dose is 150 mcg/kg body weight once daily for 2 weeks followed by 300 mcg/kg once daily for 2 weeks, thereafter the dose is increased by a maximum of 300 mcg/kg every 1 to 2 weeks to usual maintenance dose of 1 mg to 5 mg/kg body weight, which may be given once daily or in 2 divided doses. Or as prescribed by the physician.
Note: If the calculated dose for children lies between 1 and 2 mg then 2 mg may be given on alternate days for the first 2 weeks of therapy. Lamotrigine should not be administered if the calculated dose is less than 1 mg.
For Bipolar Disorder: As Monotherapy: The initial recommended dosage is 25 mg once daily which is gradually increased to 200 mg daily over 6 weeks. Dosages over 200 mg/day as monotherapy are not recommended.
For patients taking valproate: 25 mg every other day and the target dosage is 100 mg/day from week 6.
In recipients of carbamazepine (or other enzyme inducing drugs): the initial recommended dosage is 50 mg once daily which is gradually increased up to 400 mg/day from week 7. Dosages >50 mg/day can be given once daily or as two divided doses.

Administration

May be taken with or without food.

Contraindications

It is contraindicated in patients known to be hypersensitive to Lamotrigine.

Special Precautions

Lamotrigine should be given with caution to patients with hepatic or renal impairment. Patients receiving lamotrigine should be closely monitored, especially for changes in hepatic, renal and clotting functions. Children's body-weight should also be monitored. All patients should be warned to see a a doctor immediately if rashes or flu-like symptoms associated with hypersensitivity develop. The minimize the risk of developing serious skin reactions, dosage, recommendations should not exceeded. Particular care is needed in patients also receiving valproate.
Withdrawal: Withdrawal of Lamotrigine should be considered if rash, fever, flu-like symptoms, drowsiness, or worsening of seizure control occurs.
Care is required when withdrawing lamotrigine therapy. Abrupt withdrawal should be avoided unless serious skin reactions have occurred.

Adverse Reactions

Skin rashes may occur during therapy with lamotrigine, severe skin reactions including Stevens-Johnson syndrome and toxic epidermal necrolysis have been reported, especially in children, and usually occur within 8 weeks of starting lamotrigine. Symptoms such as fever, malaise, flu-like symptoms, drowsiness, lymphadenopathy, facial edema and, rarely hepatic dysfunction, leucopenia, and thrombocytopenia have also been reported in conjunction with rashes as part of a hypersensitivity syndrome.
Other adverse effects include angioedema and photosensitivity, diplopia, blurred vision, and conjunctivitis, and dizziness, drowsiness, insomnia, headache, ataxia, nystagmus, tremor, tiredness, nausea and vomiting, irritability and aggression, hallucinations, agitation and confusion.

Drug Interactions

There are complex interactions between antiepileptics and toxicity may be enhanced without a corresponding increase in antiepileptic activity. Such interactions are very variable and unpredictable and plasma monitoring is often advisable with combination therapy. The metabolism of lamotrigine is enhanced by the enzyme inducers carbamazepine, phenytoin, phenobarbital, primidone, and inhibited by valproate. Use with rifampicin significantly increased the clearance of lamotrigine.
Some estrogen-containing oral contraceptives have been shown to decrease serum concentrations of lamotrigine.

Storage

Store at temperatures not exceeding 30°C.

Action

Pharmacology: Pharmacokinetics: Lamotrigine is well absorbed from the gastrointestinal tract and peak plasma concentrations occur approximately 2.5 hours after oral administration. It is widely distributed in the body and is 55 % reported to be about 55% bound to plasma protein. It is extensively metabolized in the liver and excreted almost entirely in the urine, principally as glucuronide conjugate. It slightly induces it own metabolism and the half-life steady state is reported to be about 24 hours. Lamotrigine is distributed in the breast milk.

MedsGo Class

Anticonvulsants

LAMITOR 50 Lamotrigine 50mg Tablet 1's