Felbamate (Felbatol)

When is felbamate used ?

Felbamate is approved for use in partial epilepsy either as the sole medicine or as adjunctive therapy—that is, to be added to other seizure medicines.

Felbamate is also used in combination with other seizure medicines to treat children with Lennox Gastaut syndrome.

IMPORTANT

Felbamate is recommended as a treatment only for people whose seizures have not responded to other medications and are so severe that a substantial risk of bone marrow failure (aplastic anemia) or liver failure is considered acceptable in light of the potential benefits of felbamate. If you are in this situation, the risks will be fully explained to you and you will be asked to sign a written consent form. Before deciding to use felbamate, be sure to read about the serious side effects here and ask your doctor or pharmacist for more extensive written information.

What are the most common side effects of felbamate ?

Many people who take felbamate have few or no side effects. Those who experience undesirable effects most often complain of:

  • decreased appetite and weight loss
  • nausea
  • insomnia (sleeplessness)
  • headache

Some other side effects are:

  • poor coordination or tremor (shaking)
  • vision problems
  • dizziness
  • vomiting
  • mood changes or anxiety
  • sleepiness (especially when given in combination with other seizure medicines)

If these problems do not go away within several days, or are really bothersome, call the doctor. Sometimes the doctor can help with these side effects by changing the prescription:

  • reducing the overall amount of felbamate
  • changing the amount taken at certain times, such as taking a greater proportion of the drug at bedtime to reduce daytime sleepiness
  • prescribing smaller doses at more frequent intervals

Never stop a medication nor adjust the dose without first consulting your doctor.

People who have just started taking felbamate (or who have just started taking a larger amount) should be careful during activities that might be dangerous, until they know whether they are having any side effects.

Allergic reactions

A rash occurs in a small number of people who take felbamate. This reaction usually occurs within the first few weeks of treatment. Contact your doctor if a rash develops as it can be the warning sign of a serious allergy.

What are the most serious side effects of felbamate ?

Most people who take felbamate have either no or mild side effects that generally disappear within a short time without lasting harm. Serious reactions are extremely rare (about 1 in 4,500) but should be reported immediately. Serious symptoms for which a patient should call the doctor immediately are:

  • bleeding (for example, in the nose, gums, or skin)
  • easy bruising
  • unusual tiredness or weakness
  • shortness of breath
  • rash
  • rapid heart rate
  • high fever, shaking and chills

The risk of liver failure and a serious blood disease called aplastic anemia is 10-100 fold higher for people taking felbamate than for those not taking it. Because of this, frequent blood monitoring is required in patients taking felbamate. Also, it is extremely important that you consult your doctor immediately if you experience any of the above symptoms. Although early detection is no guarantee that the disorder will not become life-threatening, abnormalities in blood tests usually revert to normal after stopping the medication.

Persons with blood disorders, liver disorders, or disorders of the immune system may have an even higher risk of a serious reaction to felbamate. Be sure to tell your doctor if you have had any disorders of this kind.

Who should not take felbamate ?

Before deciding to use felbamate, read about the serious side effects here and ask your doctor or pharmacist for more extensive written information. Everyone considering the use of felbamate should read the box warning in the package insert and discuss the risk of life-threatening blood and liver disorders with their doctor.

People who are allergic to felbamate or to other medicines in the same family, called carbamates, should not take felbamate. People who have had liver disease, blood disorder, or an immune system problem should also avoid felbamate.

Can felbamate be taken with other medicines ?

Sometimes one kind of medicine changes the way another kind of medicine works in the body. This is true not only for prescription medicines, but also for over the counter medicines at the drug store. Felbamate can be taken with other medications, but may make certain medications less effective and vice versa as discussed next.

Does felbamate make birth control pills less effective ?

Felbamate makes birth control pills less effective, so the chances of becoming pregnant are greater. Women who use birth control pills should talk to the doctor who prescribed them prior to starting felbamate. Usually, increasing the estrogen component of the pill is all that is required. Felbamate affects other hormonal contraceptives like the Depo-Provera shot or the Norplant implant, so patients using these forms of contraception must also call their doctor prior to starting Felbamate. Hormonal injections or shots are usually not recommended in women with epilepsy, though patients can typically use the implant, although they should change it more frequently (every 10 weeks rather then every 12). Felbamate does not affect barrier types of birth control, like condoms, IUDs, and diaphragms. For more information about contraception in epilepsy, please click here.

Does felbamate affect other seizure medications ?

Felbamate affects the way the body handles many other medicines. If you take felbamate and another seizure medicine, the dosage of the other medicine may need to be adjusted.

For example, taking felbamate may increase the level of these seizure medicines in the blood:

  • Dilantin or Phenytek (phenytoin)
  • carbamazepine-epoxide (the breakdown product of Tegretol, Tegretol XR and Carbatrol)
  • phenobarbital
  • Depakene and Depakote (valproate/valproic acid)

How do other medicines affect Felbatol ?

Your body gets rid of felbamate more quickly (making it less effective) if you are also taking certain seizure medicines, such as:

  • Dilantin or Phenytek (phenytoin)
  • Tegretol, Tegretol XR, or Carbatrol (carbamazepine)
  • phenobarbital

If a woman takes felbamate during pregnancy, will it hurt the baby ?

Talk to your doctor or another health professional if you are pregnant or plan to become pregnant. There is not yet enough information available to estimate the risk of birth defects if felbamate is taken during pregnancy. Nor is enough known to compare the risk with felbamate to the risk with other seizure medicines. If you are taking felbamate and would like to become pregnant, discuss this with your doctor prior to conception.

All women who are capable of becoming pregnant should take at least 0.4 mg (400 mcg) of the vitamin called folic acid every day because it helps to prevent specific birth defects called Neural Tube Defects. (The most well-known of these is spina bifida, in which the spinal cord is not completely enclosed.) Women with epilepsy should take between 1 and 4 mg of folic acid daily during their reproductive years. If the doctor thinks a woman is at especially high risk, the larger dose of folic acid—4 mg (4000 mcg) per day—may be recommended, beginning before the woman becomes pregnant.

Some babies born to mothers taking antiepileptic medications have had inadequate blood clotting within the first 24 hours after birth. It is often recommended that the mother be given 10 to 20 mg of vitamin K per day during the last month of pregnancy to prevent this problem.

How much felbamate passes through breast milk or into the baby’s bloodstream is not known for certain. Further, how felbamate affects the baby is unknown. That said, it is strongly felt by neurologists and epileptologists that the benefits of breastfeeding largely outweigh the risks of exposing the baby to antiepileptic medications, probably including felbamate. As a matter of fact, the American Academy of Neurology and the American Epilepsy Society both recommend breastfeeding in women with epilepsy. If you are taking felbamate and want to breastfeed your baby, you should discuss this with your doctor. Please click here for more information about family planning and contraception, pregnancy and breast feeding.