Lamotrigine
LAMICTAL
What it isVoltage-gated sodium-channel blocker with additional calcium and HCN effects; seizures and bipolar maintenance.
Why this oneThe mood stabilizer with the best evidence for preventing bipolar depression, and it is weight-neutral and non-sedating.
What limits itRash risk dictates slow titration; valproate raises exposure, while enzyme inducers and estrogen lower it. Restart cautiously after interruptions.
FDA-approved for
- seizures (1994)
- bipolar maintenance (2003)
Off-label
- neuropathic pain
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Epilepsy — adjunctive therapy (partial-onset, PGTC, Lennox-Gastaut) | ≥2 yr; dosing depends on concomitant AED | 25 mg QD (25 mg QOD with valproate; 50 mg QD with inducers) | 225–375 mg/day (100–200 with valproate; 300–500 with inducers) | 700 mg/day (with inducers, no valproate) |
| Epilepsy — conversion to monotherapy (partial-onset) | ≥16 yr | Per adjunctive escalation | 500 mg/day divided BID | 500 mg/day |
| Bipolar I disorder — maintenance | Adults | 25 mg QD (25 mg QOD with valproate; 50 mg QD with inducers) | 200 mg/day (100 with valproate; 400 with inducers) | 200 mg/day |
Titration Increase at 1–2 week intervals per escalation tables; do not exceed recommended initial dose/escalation (rash risk).
Renal Reduced maintenance doses may be effective in significant renal impairment; use with caution.
Hepatic No adjustment for mild; reduce initial/escalation/maintenance ~25% for moderate–severe without ascites and ~50% for severe with ascites.
Instructions
- Do not exceed recommended initial dose and escalation to reduce rash risk
- Discontinue at first sign of rash unless clearly not drug-related
- Discontinue by tapering over ≥2 weeks (~50% per week)
- Adjust dose when starting/stopping estrogen-containing contraceptives
Cautions
- Serious skin rash
- Multiorgan hypersensitivity (DRESS)/hemophagocytic lymphohistiocytosis
- Cardiac rhythm/conduction abnormalities
- Blood dyscrasias
- Aseptic meningitis
- Suicidal behavior/ideation
Adverse reactions
- Dizziness
- Headache
- Diplopia
- Ataxia
- Nausea
- Blurred vision
- Somnolence
- Rash
- Rhinitis/pharyngitis
Pregnancy No consistent increased malformation risk detected; may decrease fetal folate; clearance increases in pregnancy.
Lactation Undefined.
⚠ BOXED WARNING
- Serious skin rashes including Stevens-Johnson syndrome
Cost, est. cash$4–$80/month
Generic entry2006
Classes and tags
Clinical profile
Legacy pregnancy categoryC
Defining liabilitySerious rash risk is concentrated during rapid titration or re-titration; dizziness and diplopia are common.
Mechanism of action: Lamotrigine ballicule
Open Lamotrigine in the interactive console ↗
Memory aids: mascots and interaction avatars
“ictal” refers to seizure
