This section provides specific dosing recommendations for patients aged 13 years and older. Specific dosing recommendations are provided depending upon concomitant AEDs or other concomitant medications.
b Drugs that induce lamotrigine glucuronidation and increase clearance, other than the specified antiepileptic drugs, include estrogen-containing oral contraceptives, rifampin, and the protease inhibitors lopinavir/ritonavir and atazanavir/ritonavir. Dosing recommendations for oral contraceptives and the protease inhibitor atazanavir/ritonavir can be found in General Dosing Considerations [see Dosage and Administration (2.1)]. Patients on rifampin and the protease inhibitor lopinavir/ritonavir should follow the same dosing titration/maintenance regimen used with antiepileptic drugs that induce glucuronidation and increase clearance [see Dosage and Administration (2.1), Drug Interactions (7), Clinical Pharmacology (12.3)].
c Dose increases at week 8 or later should not exceed 100 mg daily at weekly intervals.
|In Patients TAKING Valproatea||In Patients NOT TAKING Carbamazepine, Phenytoin, Phenobarbital, Primidone,b or Valproatea||In Patients TAKING Carbamazepine, Phenytoin, Phenobarbital, or Primidoneb and NOT TAKING Valproatea|
|Weeks 1 and 2||25 mg every other day||25 mg every day||50 mg every day|
|Weeks 3 and 4||25 mg every day||50 mg every day||100 mg every day|
|Week 5||50 mg every day||100 mg every day||200 mg every day|
|Week 6||100 mg every day||150 mg every day||300 mg every day|
|Week 7||150 mg every day||200 mg every day||400 mg every day|
|Maintenance range (week 8 and onward)||200 to 250 mg every dayc||300 to 400 mg every dayc||400 to 600 mg every dayc|
To avoid an increased risk of rash, 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 [see Boxed Warning].
Conversion from Adjunctive Therapy with Carbamazepine, Phenytoin, Phenobarbital, or Primidone to Monotherapy with Lamotrigine Extended-Release
After achieving a dose of 500 mg/day of lamotrigine extended-release using the guidelines in Table 1, the concomitant enzyme-inducing AED should be withdrawn by 20% decrements each week over a 4-week period.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 may be decreased no faster than 100 mg/day each week to achieve the monotherapy maintenance dosage range of 250 to 300 mg/day.
The regimen for the withdrawal of the concomitant AED is based on experience gained in the controlled monotherapy clinical trial using immediate-release lamotrigine.
Conversion from Adjunctive Therapy with Valproate to Monotherapy with Lamotrigine Extended-Release
The conversion regimen involves the 4 steps outlined in Table 2.
|Step 1||Achieve a dose of 150 mg/day according to guidelines in Table 1.||Maintain established stable dose.|
|Step 2||Maintain at 150 mg/day.||Decrease dose by decrements no greater than 500 mg/day/week to 500 mg/day and then maintain for 1 week.|
|Step 3||Increase to 200 mg/day.||Simultaneously decrease to 250 mg/day and maintain for 1 week.|
|Step 4||Increase to 250 or 300 mg/day.||Discontinue.|
After achieving a dosage of 250 to 300 mg/day of lamotrigine extended-release using the guidelines in Table 1, the concomitant AED should be withdrawn by 20% decrements each week over a 4-week period. No adjustment to the monotherapy dose of lamotrigine extended-release is needed.
Patients may be converted directly from immediate-release lamotrigine to lamotrigine extended-release tablets. The initial dose of lamotrigine extended-release should match the total daily dose of immediate-release lamotrigine. However, some subjects on concomitant enzyme-inducing agents may have lower plasma levels of lamotrigine on conversion and should be monitored [see Clinical Pharmacology (12.3)].
Following conversion to lamotrigine extended-release, all patients (but especially those on drugs that induce lamotrigine glucuronidation) should be closely monitored for seizure control [see Drug Interactions (7)]. Depending on the therapeutic response after conversion, the total daily dose may need to be adjusted within the recommended dosing instructions (see Table 1).
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