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Lamotrigine
Aka: Lamotrigine, Lamictal
- Indications
- Simple Partial Seizures
- Complex Partial Seizures
- Generalized Tonic Clonic Seizures
- Bipolar Disorder
- Mechanism
- Phenyltriazine anticonvulsant
- Pharmacokinetics
- Oral bioavailability: 98%
- Elimination half-life: 22 to 36 hours
- Adverse Effects: Dose related
- Dizziness
- Incoordination
- Tremor
- Ataxia
- Diplopia
- Headache
- Insomnia
- Somnolence
- Blurred Vision
- Nausea or Vomiting
- Adverse Effects: Other
- Serious skin rash (Incidence 0.08% in adults)
- Stevens Johnson Syndrome
- Toxic Epidermal Necrolysis
- Aplastic Anemia
- Thrombocytopenia
- Neutropenia
- Pancytopenia
- Aseptic Meningitis
- Serotonin Syndrome
-
Drug Interactions
- Valproic Acid
- Carbamazepine
- Phenytoin
- Phenobarbital
- Primidone
- Rifampin
- Oral Contraceptives
- Dosing: Adults
- Initial: 25 mg every other day for 2 weeks
- Next: 25 mg orally daily for 2 weeks
- Target dose: 50-100 mg orally twice daily
- Maximum dose: 400 mg/day
- Precautions
- Slow titration over 6 weeks or more reduces the risk of Stevens-Johnson Syndrome
- Dosing adjustments are needed when used with agents listed under Drug Interactions
- Monitoring
- Obtain labs monthly for the first 2 months and then every 3 to 12 months
- Complete Blood Count
- Liver Function Test
- Approach: Toxicity or Overdose
- Evaluate as Unknown Ingestion
- Obtain other toxicologic screening including Acetaminophen level, Serum Glucose
- Electrocardiogram
- Effects in Overdose
- Ventricular Dysrhythmia
- Lamictal inhibits voltage-gated Sodium channels
- Wide QRS Complex
- Treat with Sodium Bicarbonate ampules until QRS Complex narrows
- Serotonin Syndrome
- Lamictal inhibits Serotonin reuptake
- Neurologic Effects
- Sedation (most common finding in Overdose)
- Seizures
- Paradoxical (as Lamictal is foremost an anticonvulsant)
- Children may experience Seizures at doses >30 mg/kg
- Agitation
- Increased Deep Tendon Reflexes (hyperreflexia)
- Myoclonic Jerks
- Miscellaneous
- Nausea or Vomiting
- Management
- Activated Charcoal
- Consider if <1 hour from time of ingestion, and patient without aspiration risk
- QRS Widening
- See above (regarding bicarbonate)
- Seizures
- See Status Epilepticus
- Benzodiazepines
- Consider Propofol and intubation
- Consider Hemodialysis
- Disposition
- If asymptomatic at 4-6 hours after ingestion, may discharge home
- References
- Tomaszewski (2020) Crit Dec Emerg Med 34(1): 28