LAMOTRIGINE
(Lamictal)Standard Prescription
lamotrigine__mg PO__(frequency) (__mg/kg/24hr)
Dosages
Seizures:
Children 2-12 yrs (or <50 kg):
Children > 12 yrs (or >50 kg):
Bipolar Depression:
Children 2-12 yrs (or <50 kg):
Wk 1 & 2: 0.15 mg/kg/dose PO BID
Wk 3 & 4: 0.3 mg/kg/dose PO BID
Increment: 0.3 mg/kg/dose PO BID every 7-14 days
Maintenance: 2.3-3.8 mg/kg/dose PO BID (4.5-7.5 mg/kg/24 hr)
Maximum: 7.5 mg/kg/dose PO BID or 200 mg/dose PO BID
With valproic acid:
Wk 1 & 2: 0.08 mg/kg/dose PO BID
Wk 3 & 4: 0.15 mg/kg/dose PO BID
Increment: 0.15 mg/kg/dose PO BID every 7-14 days
Maintenance: 0.5-2.5 mg/kg/dose PO BID
Maximum: 2.5 mg/kg/dose PO BID or 100 mg/dose PO BID
Children > 12 yrs (or >50 kg):
Wk 1 & 2: 25 mg/dose PO daily
Wk 3 & 4: 25 mg/dose PO BID
Increment: 12.5-25 mg/dose PO daily to BID every 7-14 days (25-50 mg/24 hr)
Maintenance: 100-200 mg/dose PO BID
Maximum: 300 mg/dose PO BID
With valproic acid:
Wk 1 & 2: 12.5 mg/dose PO daily
Wk 3 & 4: 12.5 mg/dose PO BID
Increment: 12.5 mg/dose PO daily to BID every 7-14 days (25-50 mg/24 hr)
Maintenance: 50-100 mg/dose PO BID
Maximum: 150 mg/dose PO BID
Bipolar Depression:
Adolescents > 12 yrs old (or >50 kg):
Monotherapy:
Wk 1 & 2: 25 mg PO once daily
Wk 3 & 4: 50 mg PO once daily
Wk 5: 100 mg PO once daily
Maintenance: 200 mg PO once daily
With valproic acid (+/- EI-AED):
Wk 1 & 2: 25 mg PO every other day
Wk 3 & 4: 25 mg PO DAILY
Wk 5: 50 mg PO DAILY
Maintenance: 100 mg PO DAILY
Without valproic acid (+ E-I AED):
Wk 1 & 2: 50 mg PO DAILY
Wk 3 & 4: 50 mg PO BID
Wk 5: 100 mg PO BID
Wk 6: 150 mg PO BID
Maintenance: up to 200 mg PO BID
Mechanism of Action
Anticonvulsant. Lamotrigine is a member of the sodium channel blocking class of antiepileptic drugs and suppresses the release of glutamate and aspartate, two of the dominant excitatory neurotransmitters in the CNS.
Forms Supplied
tablet: 25 mg,100 mg
chewable/dispersible tablet: 5 mg (Also available but not stocked at BCCH: 150 mg tablet; 2mg chewable/dispersible tablet
chewable/dispersible tablet: 5 mg (Also available but not stocked at BCCH: 150 mg tablet; 2mg chewable/dispersible tablet
Comments
May worsen myoclonic seizures at higher doses and Dravet Syndrome.
Increased risk of rash with rapid titration. Must titrate dose slowly. Usually takes 12-15 weeks to achieve maintenance dose.
If withheld for > 5 half-lives, restart using initial dosing titration schedule.
Adverse effects: drowsiness, blurred vision, headache, insomnia, rash (related initial dose and titration frequency), Stevens-Johnson syndrome (SJS).
Skin rash can be serious and progress to SJS. All patients/families should be advised to seek medical attention if a rash develops at any time during treatment.
Allergic reaction usually develops within 10-14 days; however, it may appear in up to 3 months after treatment initiation.
Enzyme-inhibiting drugs (e.g. valproic acid) may increase half life; while enzyme-inducing drugs (e.g. phenytoin, carbamazepine) may decrease half life.
May interact with combination estrogen-progestin or progestin-only contraceptives (reduced lamotrigine levels and possible loss of contraceptive efficacy). Lamotrigine dosage adjustment and/or use of alternative contraceptive method may be necessary.
Effective for bipolar depression as monotherapy or adjunctive therapy (adults): open-label studies only in children and adolescents. Little to evidence of efficacy in acute mania or unipolar depression.
EI-AED = enzyme inhibiting anti-epileptic drug (e.g. carbamazepine, phenytoin, phenobarbital).
EI-AED = enzyme inhibiting anti-epileptic drug (e.g. carbamazepine, phenytoin, phenobarbital).
References
32, 44, 83, 94, 95, 158
Last Edited
2023-01-12 06:27:47