Adults: Table 1, the escalation regimen for lamotrigine in patients older than 12 years with epilepsy, is as follows. In weeks 1 and 2, patients not taking carbamazepine, phenytoin, phenobarbital, primidone or valproate take 25 mg every day; patients taking valproate take 25 mg every other day; patients taking carbamazepine, phenytoin, phenobarbital or primidone and not taking valproate take 50 mg per day. In weeks 3 and 4, patients not taking carbamazepine, phenytoin, phenobarbital, primidone or valproate take 50 mg per day; patients taking valproate take 25 mg every day; patients taking carbamazepine, phenytoin, phenobarbital or primidone and not taking valproate take 100 mg per day in two divided doses. From week 5 onward toward the maintenance dose, patients not taking carbamazepine, phenytoin, phenobarbital, primidone or valproate increase the dose by 50 mg per day every one to two weeks; patients taking valproate increase by 25 to 50 mg per day every one to two weeks; patients taking carbamazepine, phenytoin, phenobarbital or primidone and not taking valproate increase by 100 mg per day every one to two weeks. The usual maintenance dose for patients not taking carbamazepine, phenytoin, phenobarbital, primidone or valproate is 225 to 375 mg per day in two divided doses. For patients taking valproate, the usual maintenance dose is 100 to 200 mg per day when valproate is the only other drug involved, or 100 to 400 mg per day in one or two divided doses when other drugs that induce glucuronidation are also being taken. For patients taking carbamazepine, phenytoin, phenobarbital or primidone and not taking valproate, the usual maintenance dose is 300 to 500 mg per day in two divided doses.
Table 2 sets out the escalation regimen for lamotrigine in patients aged 2 to 12 years with epilepsy. In weeks 1 and 2, patients not taking carbamazepine, phenytoin, phenobarbital, primidone or valproate take 0.3 mg per kg per day in one or two divided doses; patients taking valproate take 0.15 mg per kg per day in one or two divided doses; patients taking carbamazepine, phenytoin, phenobarbital or primidone and not taking valproate take 0.6 mg per kg per day in two divided doses. In weeks 3 and 4, patients not taking carbamazepine, phenytoin, phenobarbital, primidone or valproate take 0.6 mg per kg per day in two divided doses; patients taking valproate take 0.3 mg per kg per day in one or two divided doses; patients taking carbamazepine, phenytoin, phenobarbital or primidone and not taking valproate take 1.2 mg per kg per day in two divided doses. From week 5 onward toward the maintenance dose, the dose should be increased every one to two weeks, calculated as 0.6 mg per kg per day for patients not taking carbamazepine, phenytoin, phenobarbital, primidone or valproate, as 0.3 mg per kg per day for patients taking valproate, and as 1.2 mg per kg per day for patients taking carbamazepine, phenytoin, phenobarbital or primidone and not taking valproate. The usual maintenance dose for patients not taking carbamazepine, phenytoin, phenobarbital, primidone or valproate is 4.5 to 7.5 mg per kg per day, up to a maximum of 300 mg per day in two divided doses. For patients taking valproate, the usual maintenance dose is 1 to 3 mg per kg per day when valproate is the only other drug involved, or 1 to 5 mg per kg per day up to a maximum of 200 mg per day in one or two divided doses when other such drugs are also being taken. For patients taking carbamazepine, phenytoin, phenobarbital or primidone and not taking valproate, the usual maintenance dose is 5 to 15 mg per kg per day, up to a maximum of 400 mg per day in two divided doses.
Table 3 is the initial weight based dosing guide for patients aged 2 to 12 years who are taking valproate, covering weeks 1 to 4. In weeks 1 and 2, a child weighing 6.7 kg to 14 kg takes 2 mg every other day; a child weighing 14.1 kg to 27 kg takes 2 mg every day; a child weighing 27.1 kg to 34 kg takes 4 mg every day; a child weighing 34.1 kg to 40 kg takes 5 mg every day. In weeks 3 and 4, a child weighing 6.7 kg to 14 kg takes 2 mg every day; a child weighing 14.1 kg to 27 kg takes 4 mg every day; a child weighing 27.1 kg to 34 kg takes 8 mg every day; a child weighing 34.1 kg to 40 kg takes 10 mg every day.
Table 4 gives the escalation regimen for lamotrigine in adults with bipolar disorder. In weeks 1 and 2, patients not taking carbamazepine, phenytoin, phenobarbital, primidone or valproate take 25 mg daily; patients taking valproate take 25 mg every other day; patients taking carbamazepine, phenytoin, phenobarbital or primidone and not taking valproate take 50 mg daily. In weeks 3 and 4, patients not taking carbamazepine, phenytoin, phenobarbital, primidone or valproate take 50 mg daily; patients taking valproate take 25 mg daily; patients taking carbamazepine, phenytoin, phenobarbital or primidone and not taking valproate take 100 mg daily in divided doses. In week 5, patients not taking carbamazepine, phenytoin, phenobarbital, primidone or valproate take 100 mg daily; patients taking valproate take 50 mg daily; patients taking carbamazepine, phenytoin, phenobarbital or primidone and not taking valproate take 200 mg daily in divided doses. In week 6, patients not taking carbamazepine, phenytoin, phenobarbital, primidone or valproate take 200 mg daily; patients taking valproate take 100 mg daily; patients taking carbamazepine, phenytoin, phenobarbital or primidone and not taking valproate take 300 mg daily in divided doses. In week 7, patients not taking carbamazepine, phenytoin, phenobarbital, primidone or valproate continue on 200 mg daily; patients taking valproate continue on 100 mg daily; patients taking carbamazepine, phenytoin, phenobarbital or primidone and not taking valproate may go up to 400 mg daily in divided doses.