From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Lamotrigine for bipolar disorder typically starts at 25 mg daily for the first two weeks, then increases to 50 mg daily for weeks 3-4, followed by 100 mg daily for weeks 5-6, and finally reaching a target maintenance dose of 200 mg daily (range 100-400 mg daily). This dosing regimen is based on the most recent and highest quality study available, which prioritizes minimizing the risk of serious rashes, including Stevens-Johnson syndrome 1. The slow titration schedule is crucial in reducing the risk of adverse effects. For patients taking valproate, the starting dose should be reduced to 25 mg every other day with a lower target dose (100-200 mg daily), as valproate inhibits lamotrigine metabolism. Conversely, patients on enzyme-inducing medications like carbamazepine require higher doses (up to 400 mg daily) and faster titration.
Some key points to consider when prescribing lamotrigine for bipolar disorder include:
- The medication is primarily effective for preventing depressive episodes in bipolar disorder rather than mania, working by stabilizing neuronal membranes through inhibition of voltage-sensitive sodium channels and modulation of glutamate release 2.
- Common side effects include headache, dizziness, and diplopia, but the medication is generally well-tolerated with minimal weight gain or cognitive effects compared to other mood stabilizers 3.
- Lamotrigine has been shown to be effective in the maintenance treatment of bipolar disorder, with a possible advantage over placebo in preventing recurrence of manic symptoms and clinical worsening 3.
- The medication is also effective in preventing depressive episodes in bipolar disorder, with a target maintenance dose of 200 mg daily (range 100-400 mg daily) 4.
Overall, lamotrigine is a valuable treatment option for bipolar disorder, offering a favorable balance of efficacy and tolerability. However, it is essential to carefully monitor patients for potential adverse effects and adjust the dosing regimen as needed to minimize risks.