chemistry

Lamotrigine

Lamotrigine is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Lamotrigine rather than just read about it. In short: Lamotrigine ( luh-MOH-trih-jeen), sold under the brand name Lamictal among others, is a medication used to treat epilepsy and stabilize mood in bipolar disorder. For epilepsy, this includes focal seizures, tonic-clonic seizures, and seizures in Lennox-Gastaut syndrome.

Key takeaways

Lamotrigine belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Lamotrigine to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Lamotrigine from memory before moving on to harder problems.

Reference excerpt

Lamotrigine ( luh-MOH-trih-jeen), sold under the brand name Lamictal among others, is a medication used to treat epilepsy and stabilize mood in bipolar disorder. For epilepsy, this includes focal seizures, tonic-clonic seizures, and seizures in Lennox-Gastaut syndrome. In bipolar disorder, lamotrigine has not been shown to reliably treat acute depression in any groups except for the severely depressed; but for patients with bipolar disorder who are not currently symptomatic, it appears to reduce the risk of future episodes of depression. Lamotrigine is also used off label for unipolar depression (major depressive disorder), treatment-resistant obsessive-compulsive disorder, and depersonalization-derealization disorder. Common side effects include nausea, sleepiness, headache, vomiting, trouble with coordination, and rash. Serious side effects include excessive breakdown of red blood cells, increased risk of suicide, severe skin reaction (Stevens–Johnson syndrome), and allergic reactions, which can be fatal. Lamotrigine is a phenyltriazine, making it chemically different from other anticonvulsants. Its mechanism of action is not clear, but it appears to inhibit release of excitatory neurotransmitters via voltage-sensitive sodium channels and voltage-gated calcium channels in neurons. Lamotrigine was first marketed in Ireland in 1991, and approved for use in the United States in 1994. It is on the World Health Organization's List of Essential Medicines. In 2023, it was the most commonly prescribed mood stabilizer and 59th most commonly prescribed medication in the United States, with more than 10 million prescriptions.

Medical uses

Epilepsy Lamotrigine is considered a first-line drug for generalized seizures (includes absence seizure, myoclonic seizure, atonic seizures, and secondarily generalized seizures such as focal-onset tonic-clonic seizures), and is used as an alternative or adjuvant medication for focal seizures. The evidence supporting the use of lamotrigine as an add-on therapy for drug-resistant generalized tonic-clonic seizures is not clear enough to inform clinical practice. Although low-certainty evidence suggests that it reduces generalized tonic-clonic seizures by 50%, the level of uncertainty indicates that the actual findings could be significantly different. Evidence supporting the use of lamotrigine as an add-on therapy for drug-resistant focal epilepsy found that it is likely effective for reducing seizure frequency and is generally well tolerated. Lamotrigine has some side effects including a risk of dizziness, nausea, ataxia, or visual disturbances such as diplopia. The long-term effects of lamotrigine have not been investigated.

Lennox–Gastaut syndrome

Lamotrigine is one of a small number of FDA-approved therapies for the form of epilepsy known as Lennox–Gastaut syndrome. It reduces the frequency of LGS seizures, and is one of two medications known to decrease the severity of drop attacks. Combination with valproate is common, but this increases the risk of Stevens–Johnson syndrome, and necessitates reduced dosing due to the interaction of these drugs.

Bipolar disorder Lamotrigine is approved in the US for maintenance treatment of bipolar I disorder. While the anticonvulsants carbamazepine and valproate are predominantly antimanics, lamotrigine has demonstrated efficacy only in preventing or reducing the risk of recurrent depressive episodes of bipolar disorder. The drug seems ineffective in the treatment of current rapid-cycling, acute mania, or acute depression in bipolar disorder. Lamotrigine has been shown to be as effective as lithium, the standard treatment for bipolar disorder, in maintenance treatment. Lamotrigine has not demonstrated clear efficacy in treating acute mood episodes, either mania or depression. It has not demonstrated effectiveness in treating acute mania, and there is controversy regarding the drug's effectiveness in treating acute bipolar depression. A paper written in 2008 by Ghaemi et al. reviewed evidence from trials that were unpublished and not referenced in the 2002 APA guidelines, and it concludes that lamotrigine has "very limited, if any, efficacy in the treatment of acute bipolar depression". A 2008 paper by Calabrese et al. examined much of the same data, and found that in five placebo-controlled studies, lamotrigine did not significantly differ from placebo in the treatment of bipolar depression. However, in a meta-analysis of these studies conducted in 2008, Geddes, Calabrese, and Goodwin found that lamotrigine was effective in individuals with bipolar depression, with a number needed to treat (NNT) of 11, or 7 in severe depression. A 2013 review concluded that lamotrigine is recommended in bipolar maintenance when depression is prominent and that more research is needed regarding its role in the treatment of acute bipolar depression and unipolar depression. No information to recommend its use in other psychiatric disorders was found.

Schizophrenia Lamotrigine, as a monotherapy, is not substantially effective against schizophrenia. However, various publications and textbooks have expressed that lamotrigine could be added to clozapine as augmentation therapy against partial or non-responding patients with schizophrenia. Patients had statistically significant improvements in positive, negative and affective symptoms. Lamotrigine does not have a statistically significant effect with antipsychotics other than clozapine, such as olanzapine, risperidone, haloperidol, and zuclopenthixol.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Lamotrigine

Start with the simplest possible case. Write down what Lamotrigine claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Lamotrigine before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Lamotrigine ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Lamotrigine

In research: Lamotrigine appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Lamotrigine in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Lamotrigine is common in secondary-school and first-year university syllabi. It links to neighbouring topics Anticonvulsants, Calcium channel blockers, Dermatoxins, so understanding it makes those chapters shorter.
In everyday life: Look for Lamotrigine outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Lamotrigine in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Lamotrigine means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Lamotrigine out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Lamotrigine in simple terms?

Why does Lamotrigine matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Lamotrigine?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Lamotrigine.