Tiagabine
Definition
Tiagabine is an anticonvulsant medication indicated for the control of seizures in the treatment of epilepsy. Epilepsy is a neurological disorder in which excessive surges of electrical energy are emitted in the brain, causing seizures.
Purpose
Tiagabine decreases abnormal electrical activity within the brain that may trigger seizures. Although tiagabine controls some types of seizures associated with epilepsy, especially partial seizures, there is no known cure for the disorder.
Description
In the United States, tiagabine is sold under the brand name Gabitril. While the exact mechanism by which tiagabine reduces seizures is unknown, the drug boosts the levels of GABA, a neurotransmitter, in the brain. Neurotransmitters such as GABA are naturally occurring chemicals that transmit messages from one neuron (nerve cell) to another. When one neuron releases GABA, it normally binds to the next neuron, transmitting information and preventing the transmission of extra electrical activity. When levels of GABA are reduced, there may not be enough GABA to sufficiently bond to the neuron, leading to extra electrical activity in the brain and seizures. Tiagabine works to block GABA from being re-absorbed too quickly into the tissues, thereby increasing the amount available to bind to neurons.
Recommended dosage
Tiagabine is taken by mouth in tablet form and is prescribed by physicians in varying dosages.
Beginning a course of treatment with tiagabine requires a gradual dose-increasing regimen. Adults and teenagers 16 years or older typical take 4 mg a day at the beginning of treatment. The prescribing physician may raise a patient's daily dosage gradually over the course of several weeks. The usual dose is not greater than 56 mg per day. The full benefits of tiagabine may not be realized until after several weeks of therapy.
A person should not take a double dose of tiagabine. If a daily dose is missed, the next dose should be taken as soon as possible. However, if it is almost time for the next dose, the missed dose is skipped.
When discontinuing treatment including tiagabine, physicians typically direct patients to gradually reduce their daily dosages. Stopping the medicine suddenly may cause seizures to return or occur more frequently.
Precautions
A physician should be consulted before taking tiagabine with certain non-prescription medications. Patients should avoid alcohol and CNS depressants (medicines that can make one drowsy or less alert, such as antihistimines, sleep medications, and some pain medications) while taking tiagabine. Tiagabine can exacerbate (potentiate) the side effects of alcohol and other medications.
Tiagabine may not be suitable for persons with a history of liver or kidney disease, mental illness, high blood presure, angina (chest pain), irregular heartbeats, or other heart problems. Before beginning treatment with tiagabine, patients should notify their physician if they consume a large amount of alcohol, have a history of drug use, are pregnant, or plan to become pregnant. Physicians often advise the use of effective birth control while taking tiagabine. Studies in animals indicate that tiagabine may cause birth defects. Patients who become pregnant while taking tiagabine should contact their physician immediately.
Side effects
Patients and their physicians should weigh the risks and benefits of tiagabine before beginning treatment. Tiagabine is usually well-tolerated, but may case a variety of usually mild side effects. Dizziness, nausea and drowsiness are the most frequently reported side effects of tiagabine. Other possible side effects include:
- trouble sleeping
- fever
- headache
- unusual tiredness or weakness
- tremors
- abdominal pain
- increased appetite
- vomiting, diarrhea or constipation
- heartburn or indigestion
- aching joints and muscles or chills
- unpleasant taste in mouth or dry mouth tingling or prickly feeling on the skin
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 notified.
Other, uncommon side effects of tiagabine can be serious. A patient taking tiagabine who experiencs any of the following symptoms should contact their physician:
- rash or bluish patches on the skin
- mood or mental changes
- shakiness or unsteady walking
- excessive anxiety
- difficulty with memory
- double vision
- numbness in a limb.
- unsteadiness or clumsiness
- speech or language problems
- difficulty breathing
- chest pain
- irregular heartbeat
- faintness or loss of consciousness
- persistent severe headaches
- persistent fever or pain
Interactions
Tiagabine may have negative interactions with some antihistimines, antidepressants, antibiotics, and monoamine oxidase inhibitors (MAOIs). Other medications such as diazepam (Valium), phenobarbital (Luminal, Solfoton), nefazodone, metronidazole, acetazolamide (Diamox), phenytoin (Dilantin), primidone, and propranolol (Inderal) may also adversely react with triagabine. Tiagabine should be used with other other seizure prevention medications only if advised by a physician.
Many anticonvulsants may decrease the effectiveness of some forms of oral contraceptives (birth control pills).
Resources
BOOKS
Weaver, Donald F. Epilepsy and Seizures: Everything You Need to Know. Richmond Hill, Ontario: Firefly Books, 2001.
OTHER
"Tiagabine." Medline Plus. National Library of Medicine. (March 20, 2004). http://www.nlm.nih.gov/medlineplus/druginfo/uspdi/203392.html.
ORGANIZATIONS
American Epilepsy Society. 342 North Main Street, West Hartford, CT 06117-2507. http://www.aesnet.org.
Epilepsy Foundation. 4351 Garden City Drive, Landover, MD 20785-7223. (800) 332-1000. http://www.epilepsyfoundation.org.
Adrienne Wilmoth Lerner
