THERAPEUTICS

Brands

• Lamictal
• Labileno
• Lamictin
• see index for additional brand names

Generic?

• Yes

Class

• Anticonvulsant, mood stabilizer, voltage-sensitive sodium channel antagonist

Commonly Prescribed For

• (bold for FDA approved)
• Maintenance treatment of bipolar I disorder
• Partial seizures (adjunctive; adults and children over age 2)
• Generalized seizures of Lennox-Gastaut syndrome (adjunctive; adults and children over age 2)
• Conversion to monotherapy in adults with partial seizures who are receiving treatment with carbamazepine, phenytoin, phenobarbital, primidone, or valproate
• Bipolar depression
• Bipolar mania (adjunctive and second-line)
• Psychosis, schizophrenia (adjunctive)
• Neuropathic pain/chronic pain
• Major depressive disorder (adjunctive)
• Other seizure types and as initial monotherapy for epilepsy

How The Drug Works

• Acts as a use-dependent blocker of voltage-sensitive sodium channels
• Interacts with the open channel conformation of voltage-sensitive sodium channels
• Interacts at a specific site of the alpha pore-forming subunit of voltage-sensitive sodium channels
• Inhibits release of glutamate and asparate

How Long Until It Works

• May take several weeks to improve bipolar depression
• May take several weeks to months to optimize an effect on mood stabilization
• Can reduce seizures by 2 weeks, but may take several weeks to months to reduce seizures

If It Works

• The goal of treatment is complete remission of symptoms (e.g., seizures, depression, pain)
• Continue treatment until all symptoms are gone or until improvement is stable and then continue treating indefinitely as long as improvement persists
• Continue treatment indefinitely to avoid recurrence of mania, depression, and/or seizures
• Treatment of chronic neuropathic pain may reduce but does not eliminate pain symptoms and is not a cure since pain usually recurs after medicine stopped

If It Doesn’t Work (for bipolar disorder)

• Many patients only have a partial response where some symptoms are improved but others persist or continue to wax and wane without stabilization of mood
• Other patients may be nonresponders, sometimes called treatment-resistant or treatment-refractory
• Consider increasing dose, switching to another agent or adding an appropriate augmenting agent
• Consider adding psychotherapy
• Consider biofeedback or hypnosis for pain
• Consider the presence of noncompliance and counsel patient
• Switch to another mood stabilizer with fewer side effects
• Consider evaluation for another diagnosis or for a comorbid condition (e.g., medical illness, substance abuse, etc.)

Best Augmenting Combos for Partial Response or Treatment-Resistance (for bipolar disorder)

• Lithium
• Atypical antipsychotics (especially risperidone, olanzapine, quetiapine, ziprasidone, and aripiprazole)
• Valproate (with caution and at half dose of lamotrigine in the presence of valproate, because valproate can double lamotrigine levels)
• Antidepressants (with caution because antidepressants can destabilize mood in some patients, including induction of rapid cycling or suicidal ideation; in particular consider bupropion; also SSRIs, SNRIs, others; generally avoid TCAs, MAOIs)

Tests

• None required
• The value of monitoring plasma concentrations of lamotrigine has not been established
• Because lamotrigine binds to melanin-containing tissues, opthalmological checks may be considered