Lamotrigine (Page 3 of 12)

2.3 Epilepsy—Conversion From Adjunctive Therapy to Monotherapy

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 tablets.

The recommended maintenance dose of lamotrigine tablets as monotherapy is 500 mg/day given in 2 divided doses.

To avoid an increased risk of rash, the recommended initial dose and subsequent dose escalations for lamotrigine tablets should not be exceeded [see Boxed Warning].

Conversion from Adjunctive Therapy with Carbamazepine, Phenytoin, Phenobarbital, or Primidone to Monotherapy with Lamotrigine Tablets

After achieving a dose of 500 mg/day of lamotrigine tablets using the guidelines in Table 1, the concomitant enzyme-inducing AED should be withdrawn by 20% decrements each week over a 4-week period. The regimen for the withdrawal of the concomitant AED is based on experience gained in the controlled monotherapy clinical trial.

Conversion from Adjunctive Therapy with Valproate to Monotherapy with Lamotrigine Tablets

The conversion regimen involves the 4 steps outlined in Table 4.

Table 4. Conversion From Adjunctive Therapy With Valproate to Monotherapy With Lamotrigine Tablets in Patients Aged 16 Years and Older With Epilepsy

Lamotrigine Tablets

Valproate

Step 1

Achieve a dose of 200 mg/day according to guidelines in Table 1.

Maintain established stable dose.

Step 2

Maintain at 200 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 300 mg/day and maintain for 1 week.

Simultaneously decrease to 250 mg/day and maintain for 1 week.

Step 4

Increase by 100 mg/day every week to achieve maintenance dose of 500 mg/day.

Discontinue.

Conversion from Adjunctive Therapy with Antiepileptic Drugs other than Carbamazepine, Phenytoin, Phenobarbital, Primidone, or Valproate to Monotherapy with Lamotrigine Tablets

No specific dosing guidelines can be provided for conversion to monotherapy with lamotrigine tablets with AEDs other than carbamazepine, phenytoin, phenobarbital, primidone, or valproate.

2.4 Bipolar Disorder

The goal of maintenance treatment with lamotrigine tablets is to delay the time to occurrence of mood episodes (depression, mania, hypomania, mixed episodes) in patients treated for acute mood episodes with standard therapy [see Indications and Usage (1.2)].

Patients taking lamotrigine tablets for more than 16 weeks should be periodically reassessed to determine the need for maintenance treatment.

Adults

The target dose of lamotrigine tablets is 200 mg/day (100 mg/day in patients taking valproate, which decreases the apparent clearance of lamotrigine, and 400 mg/day in patients not taking valproate and taking either carbamazepine, phenytoin, phenobarbital, primidone, or other drugs such as rifampin and the protease inhibitor lopinavir/ritonavir that increase the apparent clearance of lamotrigine). In the clinical trials, doses up to 400 mg/day as monotherapy were evaluated; however, no additional benefit was seen at 400 mg/day compared with 200 mg/day [see Clinical Studies (14.2)]. Accordingly, doses above 200 mg/day are not recommended.

Treatment with lamotrigine tablets is introduced, based on concurrent medications, according to the regimen outlined in Table 5. If other psychotropic medications are withdrawn following stabilization, the dose of lamotrigine tablets should be adjusted. In patients discontinuing valproate, the dose of lamotrigine tablets should be doubled over a 2-week period in equal weekly increments (see Table 6). In patients discontinuing carbamazepine, phenytoin, phenobarbital, primidone, or other drugs such as rifampin and the protease inhibitors lopinavir/ritonavir and atazanavir/ritonavir that induce lamotrigine glucuronidation, the dose of lamotrigine tablets should remain constant for the first week and then should be decreased by half over a 2-week period in equal weekly decrements (see Table 6). The dose of lamotrigine tablets may then be further adjusted to the target dose (200 mg) as clinically indicated.

If other drugs are subsequently introduced, the dose of lamotrigine tablets may need to be adjusted. In particular, the introduction of valproate requires reduction in the dose of lamotrigine tablets [see Drug Interactions (7), Clinical Pharmacology (12.3)].

To avoid an increased risk of rash, the recommended initial dose and subsequent dose escalations of lamotrigine tablets should not be exceeded [see Boxed Warning].

Table 5. Escalation Regimen for Lamotrigine Tablets in Adults with Bipolar Disorder

In Patients TAKING Valproatea

In Patients NOT TAKING Carbamazepine, Phenytoin, Phenobarbital, Primidoneb , 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 daily

50 mg daily

Weeks 3 and 4

25 mg daily

50 mg daily

100 mg daily, in divided doses

Week 5

50 mg daily

100 mg daily

200 mg daily, in divided doses

Week 6

100 mg daily

200 mg daily

300 mg daily, in divided doses

Week 7

100 mg daily

200 mg daily

up to 400 mg daily, in divided doses

a Valproate has been shown to inhibit glucuronidation and decrease the apparent clearance of lamotrigine [see Drug Interactions (7), Clinical Pharmacology (12.3)].

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), and Clinical Pharmacology (12.3)].

Table 6. Dosage Adjustments to Lamotrigine Tablets in Adults with Bipolar Disorder following Discontinuation of Psychotropic Medications

Discontinuation of Psychotropic Drugs (excluding Valproate,a Carbamazepine, Phenytoin, Phenobarbital, or Primidoneb)

After Discontinuation of Valproatea

After Discontinuation of Carbamazepine, Phenytoin, Phenobarbital, or Primidoneb

Current dose of lamotrigine tablets (mg/day) 100

Current dose of lamotrigine tablets (mg/day) 400

Weeks 1

Maintain current dose of lamotrigine tablets

150

400

Weeks 2

Maintain current dose of lamotrigine tablets

200

300

Week 3 onward

Maintain current dose of lamotrigine tablets

200

200

a Valproate has been shown to inhibit glucuronidation and decrease the apparent clearance of lamotrigine [see Drug Interactions (7), Clinical Pharmacology (12.3)].

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), and Clinical Pharmacology (12.3)].

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