Lamotrigine(la mo’ tri geen)
Apo-Lamotrigine (CAN), Gen-Lamotrigine (CAN), Lamictal, Lamictal CD, Lamictal ODT, Lamictal XRDNC, PMS-Lamotrigine (CAN), ratio-Lamotrigine (CAN)
PREGNANCY CATEGORY C
Drug class
Antiepileptic
Therapeutic Actions
Mechanism not well understood; may inhibit voltage-sensitive sodium channels, stabilizing the neuronal membrane and modulating calcium-dependent presynaptic release of excitatory amino acids.
Indications
ER form—once-daily adjunctive therapy for patients 13 yr and older with partial onset seizures and primary generalized tonic-clonic seizures
Adjunctive therapy for the treatment of Lennox-Gastaut syndrome in infants, children, and adults; primary generalized tonic-clonic seizures and partial seizures in adults and children 2 yr and older
Monotherapy in adults with partial seizures that have not been controlled by other therapies
Conversion to monotherapy in patients 13 yr and older (ER form, immediate-release) with partial seizures receiving treatment with a single enzyme-inducing antiepileptic drug
Long-term maintenance of bipolar I disorder in adults, to delay the occurrence of acute mood episodes in patients on standard therapy (immediate-release only)
Unlabeled uses: Migraine headache, post-poliomyelitis syndrome obesity, depression, restless legs syndrome, schizophrenia
Contraindications and Cautions
Contraindicated with allergy to drug, lactation.
Use cautiously with impaired hepatic, renal, or cardiac function; patients younger than 16 yr, pregnancy.
Available Forms
Tablets—25, 100, 150, 200 mg; chewable tablets—2, 5, 25, 100 mg; orally disintegrating tablets—25, 50, 100, 200 mg; ER tabletsDNC—25, 50, 100, 200 mg
Dosages
Adults
Epilepsy:
Patients taking enzyme-inducing antiepileptics (ie, carbamazepine, phenytoin, phenobarbital) and not valproic acid: 50 mg PO daily for 2 wk; then 100 mg PO daily in two divided doses for 2 wk; may increase by 100 mg/day every wk up to a maintenance dose of 300–500 mg/day in two divided doses. Patients older than 13 yr (ER tablets): wk 1–2, 50 mg/day PO; wk 3–4, 100 mg/day PO; wk 5, 200 mg/day PO; wk 6, 300 mg/day PO; wk 7, 400 mg/day PO. Range, 400–600 mg/day.
Patients taking enzyme-inducing antiepileptics (ie, carbamazepine, phenytoin, phenobarbital) and also valproic acid: 25 mg PO every other day for 2 wk; then 25 mg PO daily for 2 wk, then may increase by 25–50 mg every 1–2 wk up to a maintenance dose of 100–400 mg/day PO in two divided doses.
Conversion of patients to lamotrigine monotherapy: Titrate as above to a target dose of 500 mg/day in two divided doses, then attempt to decrease other antiepileptic by 20% weekly.
Bipolar I disorder:
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