II. Indications
III. Mechanism
- Phenyltriazine anticonvulsant
IV. Pharmacokinetics
- Oral Bioavailability: 98%
- Elimination Half-Life: 22 to 36 hours
V. Adverse Effects: Dose related
VI. Adverse Effects: Other
- Serious skin rash (Incidence 0.08% in adults)
- Prolonged QRS Interval
- Increased risk of ventricular Arrhythmia or Cardiac Arrest
- Mechanism
- Higher risk in underlying heart disease
- Coronary Artery Disease (prior Myocardial Infarction)
- Structural heart disease
- Atrioventricular Block
- Heart Failure
- Approach
- Avoid in high risk cardiovascular patients
- Consider baseline EKG in age over 60 years or Cardiovascular Risk Factors
- Avoid combining with other Sodium Channel Blockers
- References
- (2021) Presc Lett 28(6):34
- Aplastic Anemia
- Thrombocytopenia
- Neutropenia
- Pancytopenia
- Aseptic Meningitis
- Serotonin Syndrome
VII. Drug Interactions
VIII. 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
IX. Monitoring
- Obtain labs monthly for the first 2 months and then every 3 to 12 months
- Complete Blood Count
- Liver Function Test
X. 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
- Ventricular Dysrhythmia
- 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
- Activated Charcoal
- Disposition
- If asymptomatic at 4-6 hours after ingestion, may discharge home
- References
- Tomaszewski (2020) Crit Dec Emerg Med 34(1): 28
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