Tiagabine (Gabitril)

What is tiagabine used for?

Tiagabine is approved by the FDA for use as add on treatment in people who suffer from partial seizures—that is, seizures that begin in a limited area of the brain. Although not an FDA approved usage, tiagabine may also be used in infantile spasms and other difficult to control seizure types.

Besides epilepsy, what else is tiagabine used for?

Often doctors find that medicines are useful for more than one purpose. It is legal to prescribe medicines for "off-label uses" even though the FDA has not formally approved such uses. Off-label uses of tiagabine include:

  • spasticity
  • migraine headaches
  • mood disorders such as anxiety
  • pain syndromes

Although off label usage of all medications occurs widely in medicine, the FDA has cautioned against the off label use of tiagabine in patients without epilepsy. In such patients, tiagabine has been associated with an increased risk of “de novo” or new onset seizures.

What are the most common side effects of tiagabine?

The majority of people taking tiagabine tolerate it well without any unwanted side effects. Those who do experience side effects most commonly report:

  • dizziness
  • fatigue
  • nervousness
  • sleepiness
  • difficulty concentrating
  • tremor
  • weight loss

Less commonly reported side effects include:

  • nausea
  • vomiting
  • diarrhea
  • weakness
  • irritability
  • confusion
  • specific episodes of knee buckling

If any of these symptoms persist, or are truly bothersome, call your doctor, but never stop or reduce the medicine on your own. Sometimes the doctor can help with these side effects by changing the amount of tiagabine or how you take it.

Occasionally, side effects become more severe when higher doses of tiagabine are taken, or when the dosage is increased rapidly.

What are the most serious side effects of tiagabine?

Very few people have serious reactions to tiagabine. If you take it, you should be aware of them, however, so you and your family can recognize them.

About 1 in 100 people who have taken tiagabine have experienced excessive weakness. In every case, the weakness went away after the tiagabine was reduced or discontinued.

In rare cases, tiagabine causes severe confusion associated with an unrecognized or new seizure type, absence seizures. These seizures can become repetitive or continuous and constitute a medical emergency, usually treated with clonazepam (Klonopin) or lorazepam (Ativan). People with a history of absence seizures and other generalized seizure types appear to be at greatest risk.

Who should not take tiagabine?

The only people who definitely should not take tiagabine are those who are allergic to it or any of its inactive ingredients. Also, people with a diagnosis of generalized epilepsy should avoid tiagabine due to the risk of repetitive seizures and status epilepticus (!!glossary link - NEED TO ADD LINK!!).

People who have liver disease need to be cautious about taking tiagabine as it can affect liver function.

Can tiagabine be taken with other medicines?

Sometimes one kind of medicine changes the way another kind of medicine works in the body. If two kinds of medicine affect each other, the doctor may prescribe something else or change the amount to be taken.

Tiagabine has no known effect on other medicines that you may be taking. However, other medications may affect tiagabine. For example, your body gets rid of tiagabine more quickly if you are also taking certain seizure medicines, such as:

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

If this applies to you, your doctor may plan to give you more tiagabine than you would otherwise take.

Any time one of your doctors suggests starting or stopping a prescription, be sure to ask what effect it might have on the tiagabine, and whether the dosage should be increased or decreased.

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

In the United States, the Food and Drug Administration (FDA) assigns each medication to a Pregnancy Category according to whether it has been proven to be harmful in pregnancy. Tiagabine is listed in Pregnancy Category C. This indicates that caution is advised, but the benefits of the medicine may outweigh the potential risks. Studies in animals have shown some harm to the baby, but there have been no good studies in women. 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 tiagabine is taken during pregnancy. Nor is enough known to compare the risk with to the risk with other seizure medicines. That said, it is generally recommended that women take the lowest effective dose of as few medications as possible during pregnancy. Since tiagabine is rarely used alone to treat seizures, this is yet another reason for concern.

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. It is unknown how much tiagabine from the mother’s blood passes through breast milk, or how much of this actually enters the baby’s bloodstream. Further, how tiagabine 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, including tiagabine. As a matter of fact, the American Academy of Neurology and the American Epilepsy Society both recommend breastfeeding in women with epilepsy.