Definition
Felbamate is an anticonvulsant indicated for the control of seizures in the treatment of epilepsy, a neurological dysfunction in which excessive surges of electrical energy are emitted in the brain.
Purpose
Felbamate is thought to decrease abnormal activity and excitement within the central nervous system (CNS) that may trigger seizures. While felbamate controls some types of seizures associated with epilepsy, there is no known cure for the disorder. Felbamate has shown effectiveness in controlling partial seizures in adults when prescribed alone. When prescribed with other antiepileptic medicines, felbamate has shown effectiveness in managing the intractable (difficult to control) seizures of Lennox-Gastaut syndrome in children.
Description
In the United States, felbamate is sold under the brand name Felbatol and FBM. Felbamate acts to depress CNS function; however the precise mechanisms by which it exerts its therapeutic effects in the prevention of seizures is unknown.
Recommended dosage
Felbamate is taken by mouth and is available in tablet or oral suspension form. Adult patients usually take felbamate three to four times daily. The typical total daily dose for an adult or teenager over 14-years-old ranges from 1200 mg to 3600 mg. Treatment including felbamate is appropriate for some children with intractable seizures. The typical total daily dosage formula for a child is between 15 mg and 45 mg per kilogram of body weight.
Beginning a course of treatment which includes felbamate requires a gradual dose-increasing regimen. Patients typically take a reduced dose at the beginning of treatment. The prescribing physician will determine the proper beginning dosage and may raise a patient's daily dosage gradually over the course of several weeks. It may take several weeks to realize the full benefits of felbamate.
It is important to not take a double dose of felbamate. If a daily dose is missed, take it as soon as possible. However, if it is almost time for the next dose, then skip the missed dose. When ending treatment for epilepsy that includes felbamate, physicians typically direct patients to gradually taper their daily dosages. Stopping the medicine suddenly may cause seizures to return or occur more frequently.
Precautions
Prior to initiating therapy with felbamate, blood tests to check for anemia, infection, and liver function will likely be performed. Periodic blood tests are necessary to monitor liver and bone marrow function while receiving felbamate therapy, and for a period after the drug is discontinued.
Felbamate may not be suitable for persons with a history of stroke, anemia, liver or kidney disease, mental illness, diabetes, high blood presure, angina (chest pain), irregular heartbeats, or other heart problems.
Before beginning treatment with felbamate, patients should notify their physician if they consume a large amount of alcohol, have a history of drug use, are pregnant, nursing, or plan on becoming pregnant. Research in animals indicates that felbamate may inhibit fetal growth and development. Patients who become pregnant while taking felbamate should contact their physician.
Consult a physician before taking felbamate with certain non-perscription 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 felbamate.
Side effects
Patients should discuss with their physicians the risks and benefits of treatment including felbamate before taking the medication. Dizziness and nausea are the most frequently reported side effects. Most mild side effects do not require medical treatment, and may diminish with continued use of the medication. Additional possible mild side effects include anorexia (loss of appetite), vomiting, insomnia, headache, and sleepiness. If any symptoms persist or become too uncomfortable, the prescribing physician should be consulted.
Felbamate has been implicated as the cause of serious side effects, including plastic anemia (bone marrow failure) and liver failure. It is estimated that one in every 3,600 to 5,000 patients taking felbamate will eventually develop aplastic anemia, and the fatality rate of complicating aplastic anemia is nearly 30%. For this reason, felbamate is prescribed seldomly, and only after other medications have failed to control seizures. Persons taking felbamate who experience any of the following symptoms should immediately contact a physician:
- rash or purple spots on skin
- nosebleed
- yellow tint to eyes or skin
- bruising easily
- signs of infection
- weakness and fatigue
Interactions
Felbamate should be used with other other seizure prevention medications (anticonvulsants or anti-epileptic drugs [AEDs]), only if prescribed by a physician. Felbamate increases blood levels of phenytoin (Dilantin) and valproic acid (Depekene), while reducing blood levels of carbamazepine (Tegretol).
Felbamate, like many other anticonvulsants, may decrease the effectiveness of oral contraceptives (birth control pills) or contraceptives containing estrogen.
Resources
BOOKS
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.
OTHER
Dodson, W. Edwin. M.D. Hard Choices with Felbamate. Washington University School of Medicine. (April 23, 2004). http://www.neuro.wustl.edu/epilepsy/pediatric/articleFelbamate.html
"Felbamate (Systemic)." Medline Plus. National Library of Medicine. (April 23, 2004). http://www.nlm.nih.gov/medlineplus/druginfo/uspdi/202711.html
ORGANIZATIONS
American Epilepsy Society. 342 North Main Street, West Hartford, CT 06117-2507, USA. http://www.aesnet.org.
Epilepsy Foundation. 4351 Garden City Drive, Landover, MD 20785-7223. (800) 332-1000. http://www.epilepsyfoundation.org.
Adrienne Wilmoth Lerner
