Pharm
Lamotrigine
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Lamotrigine
, Lamictal
Indications
Simple Partial Seizure
s
Complex Partial Seizure
s
Generalized Tonic Clonic Seizure
s
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 Contraceptive
s
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 Interaction
s
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
)
Seizure
s
Paradoxical (as Lamictal is foremost an anticonvulsant)
Children may experience
Seizure
s at doses >30 mg/kg
Agitation
Increased
Deep Tendon Reflex
es (hyperreflexia)
Myoclonic Jerk
s
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)
Seizure
s
See
Status Epilepticus
Benzodiazepine
s
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
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