The goal of maintenance treatment with lamotrigine tablets (chewable, dispersible) 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)].

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

Adults

The target dose of lamotrigine tablets (chewable, dispersible) 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 (chewable, dispersible) 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 If other psychotropic medications are withdrawn following stabilization, the dose of lamotrigine tablets (chewable, dispersible) should be adjusted. In patients discontinuing valproate, the dose of lamotrigine tablets (chewable, dispersible) 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 (chewable, dispersible) 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 (chewable, dispersible) may need to be adjusted. In particular, the introduction of valproate requires reduction in the dose of lamotrigine tablets (chewable, dispersible) [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 (chewable, dispersible) should not be exceeded [see Boxed Warning].

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

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 in Adults with Bipolar Disorder Following Discontinuation of Psychotropic Medications

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)].