Classifications: anticonvulsant; Therapeutic: anticonvulsant
Pregnancy Category: C
25 mg, 100 mg, 150 mg, 200 mg tablets; 2 mg, 5 mg, 25 mg chewable tablets
Exact mechanism of anticonvulsant activity is not known; thought to act by inhibiting the release of glutamate, an excitatory
neurotransmitter at voltage-sensitive sodium channels, resulting in decreased seizure activity.
Anticonvulsant action results because it stabilizes neuronal membranes and inhibits neurotransmitter release (i.e., glutamate)
in brain tissue, decreasing seizure activity.
Adjunctive therapy for partial seizures in adults and children (>2 y). Generalized tonicclonic, grand mal, or myoclonic
seizures in adults, treatment of bipolar disorder.
Hypersensitivity to lamotrigine, suicidal ideation; pregnancy (category C), lactation. Safety and efficacy in children ≤2 y are not established.
Renal insufficiency, concomitant administration of other anticonvulsants, bipolar disorder, history of suicidal tendencies;
elderly; CHF, cardiac or liver function impairment. Note: Fatal rash has been reported in children <16 y.
Route & Dosage
|Partial Seizures, Patients Receiving Anticonvulsants Other Than Valproic Acid
Adult: PO Start with 50 mg q.d. for 2 wk, then 50 mg b.i.d. for 2 wk, may titrate up to 300500 mg/d in 2 divided doses (max:
Child (216 y): PO 1 mg/kg b.i.d. times 2 wk, then 2.5 mg/kg b.i.d. times 2 wk, then 5 mg/kg b.i.d. (max: 15 mg/kg/d or 400 mg/d)
Partial Seizures, Patients Receiving Valproic Acid
Adult: PO Start with 25 mg q.o.d. for 2 wk, then 25 mg q.d. for 2 wk, may titrate up to 150 mg/d in 2 divided doses (max: 200 mg/d)
Child (216 y): PO 0.2 mg/kg/d x 2 wk, then 0.5 mg/kg/d x 2 wk, then 1 mg/kg/d (max: 5 mg/kg/d or 250 mg/d)
Bipolar Disorder, Patients Not Receiving Valproate or Carbamazepine
Adult: PO Start with 25 mg q.d. for 2 wk, then 50 mg q.d. for 2 wk, then 100 mg/d for 1 wk, then 200 mg q.d.
Bipolar Disorder, Patients Receiving Valproic Acid
Adult: PO Start with 25 mg q.o.d. for 2 wk, then 25 mg q.d. for 2 wk, then 50 mg q.d. for 1 wk, then 100 mg q.d.
Bipolar Disorder, Patients Receiving Carbamazepine
Adult: PO Start with 50 mg q.d. for 2 wk, then 50 mg b.i.d. for 2 wk, then 100 b.i.d for 1 wk, then 150 mg b.i.d. for 1 wk, then 200
Reduce dose by 25% in patients with moderate or severe impairment (without ascites); reduce by 50% in patients with
severe impairment and ascites.
- Note: Reduced dose may be warranted with renal and hepatic impairment.
- Ensure that chewable tablets are chewed or crushed before being swallowed with a liquid.
- When discontinued, drug should be tapered off gradually over a 2-wk period, unless patient safety is at risk.
Adverse Effects (≥1%)CNS: Dizziness, ataxia, somnolence, headache,
aphasia, vertigo, confusion, slurred speech, irritability, depression
, incoordination, hostility. GI: Nausea,
vomiting, anorexia, abdominal pain, diarrhea, dyspepsia, constipation
Hematuria, dysmenorrhea, vaginitis
. Special Senses: Diplopia, blurred vision. Musculoskeletal:
Peripheral neuropathy, chills, tremor, arthralgia. Skin:
Rash (including Stevens-Johnson syndrome, toxic epidermal necrolysis
), urticaria, pruritus, alopecia, acne
. Respiratory: Rhinitis,
Interactions Drug: Carbamazepine, phenobarbital, primidone, phenytoin, fosphenytoin, oral contraceptives
may decrease lamotrigine levels. Valproic acid
may increase lamotrigine levels. Lamotrigine may decrease serum levels of valproic acid.
May affect efficacy
of oral contraceptives
. Chronic acetaminophen
use may affect serum concentrations of lamotrigine. Herbal: Ginkgo
may decrease anticonvulsant effectiveness. Evening primrose
oil may affect seizure threshold.
Readily absorbed from GI tract; 98% reaches systemic circulation. Onset:
12 wk. Peak:
14 h. Distribution:
55% protein bound; crosses placenta; distributed into breast milk. Metabolism:
In liver to inactive metabolite. Elimination:
Can induce own metabolism; excreted in urine. Half-Life:
Assessment & Drug Effects
- Withhold drug if rash develops and immediately report to physician.
- Monitor the plasma levels of lamotrigine and other anticonvulsants when given concomitantly.
- Monitor patients with bipolar disorder for worsening of their symptoms and suicidal ideation. Withhold the drug and immediately
report to physician.
- Monitor for adverse reactions when lamotrigine is used with other anticonvulsants, especially valproic acid.
- Be aware of drug interactions and closely monitor when interacting drugs are added or discontinued.
Patient & Family Education
- Do not take drug if a skin rash develops. Contact your physician immediately.
- Notify physician for any of the following: Worsening seizure control, skin rash, ataxia, blurred vision or diplopia, fever
or flu-like symptoms.
- Do not drive or engage in other potentially hazardous activities until response to the drug is known.
- Use protection from sunlight or ultraviolet light until tolerance is known; drug increases photosensitivity.
- Women using oral contraceptives to avoid pregnancy should add a barrier contraceptive.
- Schedule periodic ophthalmologic exams with long-term use.
- Do not discontinue lamotrigine abruptly.