What is lamotrigine, and how does it work (mechanism of action)?
Lamotrigine is an oral drug that is used
primarily for treating seizures. It is chemically unrelated to other
anti-seizure drugs. The precise mechanism by which lamotrigine exerts its
anti-seizure action is not known. The FDA approved lamotrigine in December 1974.
What brand names are available for lamotrigine?
Lamictal, Lamictal CD, Lamictal ODT, Lamictal XR, Lamictal
Starter
Is lamotrigine available as a generic drug?
Yes
Do I need a prescription for lamotrigine?
Yes
What are the side effects of lamotrigine?
WARNING
Severe, life-threatening rashes have occurred with lamotrigine. The risk of rash is increased if the dose is increased faster than recommended or if patients also are taking valproic acid. Patients taking lamotrigine should report any rash to a physician immediately, as there's no way to tell at the onset whether the rash will be mild or severe.
Common side effects
The most common side effects of lamotrigine are:
- dizziness,
- somnolence,
- headache,
- double vision,
- blurred vision,
- nausea,
- vomiting, and
- rash.
Other important side effects include:
- increased risk of developing aseptic meningitis and
- reduced white blood cells, red blood cells, and platelets.
- suicidal thoughts or behaviors
Multiorgan failure, including fatal liver disease rarely has been observed during lamotrigine treatment.
As a general rule, anti-seizure medications should not be abruptly stopped because of the possibility of increasing the frequency of seizures. In most cases, the dose of lamotrigine should be gradually lowered over a period of at least two weeks. Antiepileptic medications have been associated with an increased risk of suicidal thinking and behavior. Anyone considering the use of antiepileptic drugs must balance this risk of suicide with the clinical need for the drugs. Patients who are started on therapy should be closely observed for clinical worsening, suicidal thoughts, or unusual changes in behavior.
What is the dosage for lamotrigine?
The dose of immediate release lamotrigine for seizures in
patients not taking
valproic acid
(Depakote, Depakote ER, Depakene, Depacon, Stavzor), but taking seizure medications that reduce lamotrigine blood levels (for example, phenobarbitol,
phenytoin
[Dilantin, Dilantin-125], carbamazepine
[Tegretol],
primidone) is 50 mg once daily for two weeks, followed by 100 mg daily given in
two divided doses for two weeks. Thereafter, the dose is increased by 100 mg
daily every 1-2 weeks up to the usual maintenance dose of 300 to 500 mg daily
given as a divided dose.
In patients who are taking valproic acid in which it
increases blood levels of lamotrigine, the initial dose of lamotrigine is 25 mg
every other day for two weeks, then 25 mg once daily for two weeks. After 4
weeks the dose is slowly increased by 25 to 50 mg per day every one to two weeks
until a dose of 100 to 400 mg once daily or divided twice daily is reached. The
maintenance dose when using extended release tablets is 200 to 600 mg once
daily.
The target dose for treating bipolar disorder is 100 to 400 mg daily.
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Which drugs or supplements interact with lamotrigine?
Lamotrigine can interact with valproic acid. When
lamotrigine is initiated in patients already receiving valproic acid, the blood
concentrations of valproic acid can decrease over a 3-week period. This may
result in loss of seizure control. Valproic acid increases lamotrigine levels.
The risk of severe
skin rash may be increased by combining lamotrigine with
valproic acid. There may be a higher incidence of dizziness, double vision, and
blurred vision in patients receiving carbamazepine together with lamotrigine.
The mechanism of this interaction is unclear.
Estrogen containing oral
contraceptives, phenobarbitol, primidone, phenytoin, and rifampin reduce the
blood levels of lamotrigine by 40%-50% by increasing the breakdown of
lamotrigine in the liver. This may result in reduced efficacy if the dose of
lamotrigine is not adjusted.
QUESTION
If you have had a seizure, it means you have epilepsy.
See Answer
Is lamotrigine safe to take if I’m pregnant or breastfeeding?
Use of lamotrigine during
pregnancy has not been adequately
evaluated.
Lamotrigine is secreted into human breast milk.
Because the effects on the infant are unknown,
breastfeeding while taking lamotrigine is not recommended.
What else should I know about lamotrigine?
What preparations of lamotrigine are available?
- Tablets: 25, 100, 150, and 200 mg.
- Tablets, chewable
(CD): 2, 5, and 25 mg. - Tablets, orally disintegrating (ODT): 25, 50, 100, and
200 mg. - Tablets, extended release (XR): 25, 50, 100, 200, 250, and300 mg.
How should I keep lamotrigine stored?
Tablets should be stored at room temperature, between 15 C – 30 C
(59 F – 86 F).