Lamotrigine is a mood stabilizer, primarily used to manage brain conditions. It is available in various forms, including tablets that can be swallowed, chewed, or dissolved in water. It works by calming overactive nerves in the brain.
Conditions Treated by Lamotrigine
Lamotrigine is prescribed for several conditions, primarily for bipolar disorder and specific seizure types. For adults with bipolar disorder, lamotrigine is approved for maintenance treatment, helping to delay the recurrence of mood episodes, including depression. It is especially useful in preventing future depressive episodes.
Lamotrigine is not typically used for acute manic or depressive episodes. Other mood stabilizers like lithium or valproate are often preferred for managing acute mania. However, lamotrigine is a first-line treatment for specific seizure types, such as primary generalized tonic-clonic seizures and those associated with Lennox-Gastaut syndrome. It helps prevent seizures by slowing down electrical signals in the brain.
How Lamotrigine Works
While its exact mechanism is still being fully understood, lamotrigine primarily stabilizes neuronal membranes. It does this by selectively binding to and inhibiting voltage-gated sodium channels in neurons. By blocking these sodium channels, it reduces the excessive electrical activity in the brain that can contribute to both seizures and mood instability.
It also modulates the release of certain neurotransmitters. Lamotrigine inhibits the release of excitatory neurotransmitters like glutamate and aspartate. Excessive glutamate activity is thought to contribute to both epilepsy and bipolar disorder, so reducing its release helps calm overactive brain signals.
Important Considerations for Lamotrigine Use
Dosing and Titration
Lamotrigine requires slow, gradual dosage increases, known as titration, to minimize the risk of severe skin rashes. Treatment typically begins with a low dose, gradually increasing over several weeks until a target dose, often between 200 mg and 400 mg daily, is reached.
The titration schedule can vary based on other medications a person is taking. For instance, if valproate is also being used, a slower titration schedule is necessary. Conversely, if enzyme-inducing medications like carbamazepine or phenytoin are present, a faster titration might be considered, though this requires careful monitoring. If three or more consecutive doses are missed, restarting the titration process from the beginning is generally recommended due to increased rash risk.
Common Side Effects
Common side effects of lamotrigine are generally mild. These can include headaches, dizziness, drowsiness, nausea, diarrhea, stomach pain, tremors, blurred or double vision, and difficulty sleeping. These often improve over time as the body adjusts.
Serious Side Effects
Lamotrigine can cause serious side effects, including severe skin rashes. Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) are severe forms of these rashes, characterized by flu-like symptoms followed by a spreading red or purple rash that can blister and cause skin peeling. These severe reactions are more likely to occur within the first eight weeks of starting the medication or if the dose is increased too quickly. Immediate medical attention is necessary if any rash develops, especially if accompanied by fever, flu-like symptoms, or swollen glands.
Another rare but serious immune system disorder associated with lamotrigine use is Hemophagocytic Lymphohistiocytosis (HLH). This condition involves an aggressive over-activation of immune cells, leading to widespread inflammation throughout the body. Symptoms can include fever, enlarged liver or spleen, swollen lymph nodes, neurological symptoms, and abnormalities in blood cell counts. These symptoms typically appear between 8 and 24 days after starting treatment.
Drug Interactions
Lamotrigine can interact with several other medications, which may affect its levels in the body and impact its effectiveness or increase side effects. Valproate significantly raises lamotrigine blood levels. This interaction can worsen lamotrigine side effects like dizziness and increase the risk of severe skin reactions, necessitating a reduced lamotrigine dose when combined.
Hormonal contraceptives can decrease lamotrigine levels, potentially reducing its effectiveness. This interaction can lead to a loss of seizure control or worsening of mood symptoms. Conversely, if a person stops taking oral contraceptives while on lamotrigine, levels may increase, which might require a dose adjustment to prevent toxicity. Other anti-seizure medications like carbamazepine and phenytoin can lower lamotrigine levels, potentially requiring a higher lamotrigine dose for effective treatment.
Monitoring
Routine blood level monitoring of lamotrigine is not always necessary but may be considered if there are signs of the medication not working, concerns about adherence, or potential toxicity. Patients are advised to monitor themselves for any signs of hypersensitivity, such as rashes or other skin changes, and to promptly report these to their doctor. Monitoring for changes in seizure frequency or duration, and any shifts in mood or suicidal thoughts, is also advised.