Lamotrigine is an anticonvulsant medication used in the treatment of epilepsy. Epilepsy is a neurological disorder in which excessive surges of electrical energy are emitted in the brain, causing seizures. Lamotrigine is usually reserved for difficult-to-control seizures that have not responded to other anticonvulsant medications. In psychiatry, lamotrigine is also indicated in the treatment of bipolar disorder (manic-depression).
While lamotrigine controls seizures associated with epilepsy, there is no known cure for the disorder. Although the precise mechanism by which lamotrigine exerts its therapeutic effect is unknown, lamotrigine is thought to act at sodium channels in the neuron (nerve cell) to reduce the amount of excitatory neurotransmitters that the nerve cell releases. Neurotransmitters are chemicals that aid in the transfer of nerve impulses from one nerve junction to the next. With decreased levels of these neurotransmitters, the electrical activity in the brain that triggers seizures is reduced.
In the treatment of bipolar disorders, lamotrigine's effect upon neurochemicals stabilizes mood, preventing sudden, unpredictable, and severe episodes of mania and depression.
For the treatment of epilepsy-related seizures, lamotrigine may be used alone or in combination with other anti-epileptic drugs (AEDs) or anticonvulsants. In the United States, lamotrigine is sold under the brand name Lamictal.
Lamotrigine is taken orally, in either tablet or chewable form. Chewable tablets may be dispersed into a liquid solution, according to the prescribing physician's instructions. Lamotrigine is prescribed by physicians in varying daily dosages, usually ranging 200–900 mg per day divided into two doses.
Beginning any course of treatment that includes lamotrigine requires a gradual dose-increasing regimen. The safety and effectiveness of lamotrigine in children under age 18 have not been proven; therefore, the drug is seldom used in children. Adults typically take an initial dose for the first two weeks that is slowly increased over time. It may take several weeks to realize the full benefits of lamotrigine, especially in those patients taking lamotrigine for the treatment of bipolar disorders.
A double dose of lamotrigine should not be taken. If a dose is missed, it should be taken as soon as possible. However, if it is within four hours of the next dose, then the missed dose should be skipped. When ending a course of treatment that includes lamotrigine, physicians typically direct patients to gradually taper down their daily dosages over a period of several weeks. Stopping the medicine suddenly may severely alter mood or cause seizures to occur, even in patients taking lamotrigine for the treatment of bipolar disorders.
A physician should be consulted before taking lamotrigine with certain non-prescription medications. Patients should avoid alcohol and CNS depressants (medications that make one drowsy or tired, such as antihistimines, sleep medications, and some pain medications), while taking lamotrigine. Lamotrigine can exacerbate the side effects of alcohol and some other medications. Alcohol may also increase the risk or frequency of seizures.
Lamotrigine may not be suitable for persons with a history of liver or kidney disease, depressed renal function,
Lamotrigine's safety during pregnancy has not been established. Persons taking lamotrigine (and other AEDs or anticonvulsants) should be aware that many AEDs and anticonvulsants cause birth defects. Patients who become pregnant while taking any AED or anticonvulsants should contact their physician immediately.
Lamotrigine is generally well tolerated. However, in some patients, lamotrigine may produce some of the traditionally mild side effects associated with anticonvulsants. Headache, nausea, and unusual tiredness and weakness are the most frequently reported side effects of anticonvulsants. Other possible side effects that do not usually require medical attention include:
- mild coordination problems
- mild dizziness
- abdominal pain
- sinus pain
- sleepiness or sleeplessness
- diarrhea or constipation
- heartburn or indigestion
- aching joints and muscles or chills
- unpleasant taste in mouth or dry mouth
Many of these side effects disappear or occur less frequently during treatment as the body adjusts to the medication. However, if any symptoms persist or become too uncomfortable, the prescribing physician should be consulted.
Other, uncommon side effects of lamotrigine can be serious and may indicate an allergic reaction. Severe and potentially life-threatening rashes have occurred during treatment with lamotrigine, occurring approximately once in every 1,000 persons who take the drug. In the unusual event that this rash develops, it normally occurs within the first eight weeks of treatment. A patient taking lamotrigine who experiences any of the following symptoms should contact a physician immediately:
- rash or bluish patches on the skin
- sores in the mouth or around the eyes
- depression or suicidal thoughts
- mood or mental changes, including excessive fear, anxiety, hostility
- general loss of motor skills
- persistent lack of appetite
- altered vision
- difficulty breathing
- chest pain or irregular heartbeat
- faintness or loss of consciousness
- persistent, severe headaches
- persistent fever or pain
Lamotrigine may have negative interactions with some antacids, antihistamines, antidepressants, antibiotics, and monoamine oxidase inhibitors (MAOIs). Other medications such as HIV protease inhibitors (indinavir), ritonavir (Norvir), ipratropium (Atrovent), isoniazid, phenobarbital (Luminal, Solfoton), nefazodone, metronidazole, acetazolamide (Diamox), propranolol (Inderal), rifampin (Rifadin, Rimactane), and warfarin may also adversely react with lamotrigine. Oral contraceptives (birth control pills) may decrease the amount of lamotrigine absorbed by the body.
Lamotrigine may be used with other seizure prevention medications, if advised by a physician.
Devinsky, Orrin, M. D., Epilepsy: Patient and Family Guide, 2nd ed. Philadelphia: F. A. Davis Co., 2001.
Weaver, Donald F. Epilepsy and Seizures: Everything You Need to Know. Toronto: Firefly Books, 2001.
"Lamotrigine." Medline Plus. National Library of Medicine. May 6, 2004 (June 1, 2004). <http://www.nlm.nih.gov/medlineplus/druginfo/uspdi/202786.html>.
"Lamotrigine." Yale New Haven Health Service Drug Guide. May 6, 2004 (June 1, 2004). <http://yalenewhavenhealth.org/library/healthguide/enus/drugguide/topic.asp?hwid=multumd03809a1>.
Epilepsy Foundation. 4351 Garden City Drive, Landover, MD 20785-7223. (800) 332-1000. <http://www.epilepsyfoundation.org>.
American Epilepsy Society. 342 North Main Street, West Hartford, CT 06117-2507. <http://www.aesnet.org>.
Adrienne Wilmoth Lerner