Lamotrigine Dosage

This dosage information may not include all the information needed to use Lamotrigine safely and effectively. See additional information for Lamotrigine.

The information at Drugs.com is not a substitute for medical advice. ALWAYS consult your doctor or pharmacist.

Usual Adult Dose for:

Usual Pediatric Dose for:

Additional dosage information:

Usual Adult Dose for Seizure Prophylaxis

Added to an Antiepileptic Drug Regimen Containing Valproic Acid:
Weeks 1 and 2: 25 mg every other day
Weeks 3 and 4: 25 mg every day
Usual maintenance dose: 100 to 400 mg/day (1 or 2 divided doses). To achieve maintenance, doses may be increased by 25 to 50 mg/day every 1 to 2 weeks. The usual maintenance dose in patients adding lamotrigine to valproic acid alone ranges from 100 to 200 mg/day.

Added to Enzyme-Inducing Antiepileptic Drugs (Without Valproic Acid)
Weeks 1 and 2: 50 mg/day
Weeks 3 and 4: 100 mg/day in two divided doses
Usual maintenance dose: 300 to 500 mg/day (in two divided doses). To achieve maintenance, doses may be increased by 100 mg/day every 1 to 2 weeks.

For patients receiving enzyme-inducing AEDs but not valproate:
Initial dose: 50 mg orally once a day for 2 weeks, then increase to 50 mg orally twice a day for 2 weeks.
Maintenance dose: 150 to 250 mg orally twice a day.
Dose may be increased by 100 mg/day every week.
Maintenance doses as high as 700 mg/day have been used.


Escalation regimen for lamotrigine extended release:
For use in Primary Generalized Tonic-Clonic and Partial Onset Seizures

Treatment with lamotrigine is introduced based on concurrent medications.

Weeks 1 and 2:
For patients not taking Carbamazepine, Phenytoin, Phenobarbital, Primidone or Valproate: 25 mg daily
For patients taking Valproate: 25 mg every other day
For patients taking Carbamazepine, Phenytoin, Phenobarbital, or Primidone and not taking Valproate: 50 mg daily

Weeks 3 and 4:
For patients not taking Carbamazepine, Phenytoin, Phenobarbital, Primidone or Valproate: 50 mg daily
For patients taking Valproate: 25 mg daily
For patients taking Carbamazepine, Phenytoin, Phenobarbital, or Primidone and not taking Valproate: 100 mg daily

Week 5:
For patients not taking Carbamazepine, Phenytoin, Phenobarbital, Primidone or Valproate: 100 mg daily
For patients taking Valproate: 50 mg daily
For patients taking Carbamazepine, Phenytoin, Phenobarbital, or Primidone and not taking Valproate: 200 mg daily

Week 6:
For patients not taking Carbamazepine, Phenytoin, Phenobarbital, Primidone or Valproate: 150 mg daily
For patients taking Valproate: 100 mg daily
For patients taking Carbamazepine, Phenytoin, Phenobarbital, or Primidone and not taking Valproate: 300 mg daily

Week 7:
For patients not taking Carbamazepine, Phenytoin, Phenobarbital, Primidone or Valproate: 200 mg daily
For patients taking Valproate: 150 mg daily
For patients taking Carbamazepine, Phenytoin, Phenobarbital, or Primidone and not taking Valproate: up to 400 mg daily

Maintenance Range (Week 8 and onward):
For patients not taking Carbamazepine, Phenytoin, Phenobarbital, Primidone or Valproate: 300 mg to 400 mg daily
For patients taking Valproate: 200 mg to 250 mg daily
For patients taking Carbamazepine, Phenytoin, Phenobarbital, or Primidone and not taking Valproate: 400 mg to 600 mg daily

Dose increases at week 8 or later should not exceed 100 mg daily at weekly intervals.

As other drugs are subsequently introduced or withdrawn, the dose of lamotrigine may need to be adjusted.

Conversion from adjunctive therapy to monotherapy with lamotrigine extended-release:

The goal of the transition regimen is to attempt to maintain seizure control while mitigating the risk of serious rash associated with the rapid titration of lamotrigine extended-release.

The recommended maintenance dosage range of lamotrigine extended-release as monotherapy is 250 to 300 mg given once daily. The recommended initial dose and subsequent dose escalations for lamotrigine extended-release should not be exceeded.

Conversion from adjunctive therapy with carbamazepine, phenytoin, phenobarbital, or primidone to monotherapy with lamotrigine extended-release: After achieving a dosage of 500 mg/day the concomitant enzyme-inducing AED should be withdrawn by 20% decrements each week over a 4-week period. Two weeks after completion of withdrawal of the enzyme-inducing AED, the dosage of lamotrigine extended-release should be decreased no faster than 100 mg/day each week to achieve the monotherapy maintenance dosage range of 250 to 300 mg/day.

Conversion from adjunctive therapy with valproate to monotherapy with lamotrigine extended-release: The conversion regimen involves 4 steps:
Step 1: Achieve a lamotrigine extended-release dosage of 150 mg/day according to dosing guidelines. Maintain established stable dose of valproate.
Step 2: Maintain lamotrigine extended-release dosage at 150 mg/day and decrease valproate dosage by decrements no greater than 500 mg/day/week to 500 mg/day and then maintain for 1 week.
Step 3: Increase lamotrigine extended-release dosage to 200 mg/day and simultaneously decrease valproate dosage to 250 mg/day and maintain for 1 week.
Step 4: Increase lamotrigine extended-release dosage to 250 or 300 mg/day and discontinue valproate.

Usual Adult Dose for Bipolar Disorder

Treatment with lamotrigine is introduced based on concurrent medications.

Weeks 1 and 2
For patients not taking carbamazepine (or other enzyme-inducing drugs) or valproate: 25 mg daily
For patients taking valproate: 25 mg every other day
For patients taking carbamazepine (or other enzyme-inducing drugs) and not taking valproate: 50 mg daily

Weeks 3 and 4
For patients not taking carbamazepine (or other enzyme-inducing drugs) or valproate: 50 mg daily
For patients taking valproate: 25 mg daily
For patients taking carbamazepine (or other enzyme-inducing drugs) and not taking valproate: 100 mg daily in divided doses

Weeks 5
For patients not taking carbamazepine (or other enzyme-inducing drugs) or valproate: 100 mg daily
For patients taking valproate: 50 mg daily
For patients taking carbamazepine (or other enzyme-inducing drugs) and not taking valproate: 200 mg daily in divided doses

Weeks 6
For patients not taking carbamazepine (or other enzyme-inducing drugs) or valproate: 200 mg daily
For patients taking valproate: 100 mg daily
For patients taking carbamazepine (or other enzyme-inducing drugs) and not taking valproate: 300 mg daily in divided doses

Weeks 7
For patients not taking carbamazepine (or other enzyme-inducing drugs) or valproate: 200 mg daily
For patients taking valproate: 100 mg daily
For patients taking carbamazepine (or other enzyme-inducing drugs) and not taking valproate: up to 400 mg daily in divided doses

As other drugs are subsequently introduced or withdrawn, the dose of lamotrigine may need to be adjusted.

Usual Pediatric Dose for Seizure Prophylaxis

Dosage depends on patient's concomitant medications (i.e., valproic acid, enzyme-inducing AEDs specifically phenytoin, phenobarbital, carbamazepine, and primidone), or AEDs other than carbamazepine, phenytoin, phenobarbital, primidone, or valproic aced. Patients receiving concomitant rifampin or other drugs that induce lamotrigine glucuronidation and increase clearance should follow the same dosing regimen as that used with anticonvulsants that have this effect (e.g., phenytoin, phenobarbital, carbamazepine, and primidone).

Added to an antiepileptic drug regimen therapy:
Children 2 to 12 years: Immediate release formulation: (only whole tablets should be used for dosing): children 2 to 6 years will likely require maintenance doses in the higher end of recommended range; patients weighing less than 30 kg may need as much as a 50% increase in maintenance dose, compared with patients weighing greater than 30 kg; titrate dose to clinical effect.

For patients taking enzyme-inducing antiepileptic drugs (AEDs) other than carbamazepine, phenytoin, phenobarbital, primidone, or valproic acid:
Weeks 1 and 2: 0.3 mg/kg/day in 1 to 2 divided doses; round dose down to nearest whole tablet.
Weeks 3 and 4: 0.6 mg/kg/day in two divided doses; round dose down to nearest whole tablet.
Maintenance dose: Titrate dose to effect; after week 4, increases dose every 1 to 2 weeks by a calculated increment; calculate increment as 0.6 mg/kg/day rounded down to the nearest whole tablet; add this amount to the previously administered daily dose; usual maintenance: 4.5 to 7.5 mg/kg/day in 2 divided doses.
Maximum dose: 300 mg/day

Patients receiving AED regimens containing valproic acid:
Weeks 1 and 2: 0.15 mg/kg/day in 1 to 2 divided doses; round dose down to the nearest whole tablet; use 2 mg every other day for patients weighing greater than 6.7 kg and less than 14 kg.
Weeks 3 and 4: 0.3 mg/kg/day in 1 to 2 divided doses; round dose down to the nearest whole tablet.
Maintenance dose: Titrate dose to effect; after week 4, increase dose every 1 to 2 weeks by a calculated increment; calculate increment as 0.3 mg/kg/day rounded down to the nearest whole tablet; add this amount to the previously administered daily dose; usual maintenance: 1 to 5 mg/kg/day in 1 to 2 divided doses.
Maximum dose: 200 mg/day. Note: Usual maintenance dose in children adding lamotrigine to valproic acid alone: 1 to 3 mg/kg/day

For patients receiving AED regimens without valproic acid:
Weeks 1 and 2: 0.6 mg/kg/day in 2 divided doses; round dose down to the nearest whole tablet.
Weeks 3 and 4: 1.2 mg/kg/day in 2 divided doses; round dose down to the nearest whole tablet.
Maintenance dose: titrate dose to effect; after week 4, increase dose every 1 to 2 weeks by a calculated increment; calculate increment as 1.2 mg/kg/day rounded down to the nearest whole tablet; add this amount to the previously administered daily dose; usual maintenance dose is 5 to 15 mg/kg/day in 2 divided doses.
Maximum dose: 400 mg/day

Renal Dose Adjustments

Use with caution and consider lower maintenance doses on patients with renal dysfunction.

Liver Dose Adjustments

No dosage adjustments are needed in patients with mild hepatic dysfunction. Initial, escalation, and maintenance doses should generally be reduced by approximately 25% in patients with moderate and severe hepatic dysfunction without ascites and 50% in patients with severe liver impairment with ascites. Escalation and maintenance doses may be adjusted according to clinical response.

Dose Adjustments

The smallest available strength of lamotrigine chewable dispersible tablets is 2 mg, and only whole tablets should be administered. If the calculated dose cannot be achieved using whole tablets, the dose should be rounded down to the nearest whole tablet.

If the decision is made to restart a patient who has discontinued lamotrigine, the need to restart with the initial dosing recommendations should be assessed. The greater the interval of time since the previous dose, the greater consideration should be given to restarting with the initial dosing recommendations. If a patient has discontinued lamotrigine for a period of more than five half-lives, it is recommended that initial dosing recommendations and guidelines be followed. (Please note that the half-life of lamotrigine is affected by concomitant medications).

Discontinuing therapy: Children and Adults: Do not rapidly discontinue; when discontinuing lamotrigine therapy, gradually decrease the dose by about 50% per week and taper over at least 2 weeks unless safety concerns require a more rapid withdrawal. Note: If discontinuing other anticonvulsants and maintaining lamotrigine therapy, keep in mind that discontinuing carbamazepine, phenytoin, phenobarbital, primidone, or other drugs, such as rifampin, that induce lamotrigine glucuronidation should be expected to prolong the half-life of lamotrigine; discontinuing valproic acid should shorten the half-life of lamotrigine; monitor patient closely; dosage change may be needed.

Dialysis

Lamotrigine is removed an average of 20% in 4 hours of hemodialysis.

Other Comments

When discontinuing therapy, a stepwise reduction of dose over at least two weeks is recommended unless safety concerns require a more rapid withdrawal.

Lamotrigine extended-release should not be chewed, crushed, or divided.

If discontinuing other anticonvulsants and maintaining lamotrigine therapy, it should be noted that discontinuing carbamazepine, phenytoin, phenobarbital, primidone, or other drugs, such as rifampin, that induce lamotrigine glucuronidation should prolong the half-life of lamotrigine. Discontinuing valproic acid should shorten the half-life of lamotrigine. The patient should be closely monitored for any necessary dose changes.

Chewable Dispersible Tablets:
Lamotrigine chewable dispersible tablets may be swallowed whole, chewed, or dispersed in water or diluted fruit juice. If the tablets are chewed, a small amount of water or diluted fruit juice should also be consumed to aid in swallowing. To disperse lamotrigine chewable dispersible tablets, add the tablets to a small amount of liquid (one teaspoon, or enough to cover the medication). Approximately one minute later, when the tablets are completely dispersed, swirl the solution and consume the entire quantity immediately. No attempt should be made to administer partial quantities of the dispersed tablets.

Orally Disintegrating Tablets (ODT):
Lamotrigine orally disintegrating tablets should be placed onto the tongue and moved around in the mouth. The tablet will disintegrate rapidly, can be swallowed with or without water, and can be taken with or without food.

Lamotrigine may be taken with or without food.

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