Topamax For Epilepsy and Migraines
Topamax is an anticonvulsant drug produced by Ortho-McNeil Neurologics, a division of Johnson & Johnson. It was originally approved in 1997 as a treatment for epilepsy, but in 2004, the Food & Drug Administration (FDA) approved Topamax for the prevention of migraines. In children, Topamax is also approved for the treatment of Lennox-Gastaut syndrome (a disorder that causes seizures and developmental delay).
Topamax is also used off-label as a treatment for bipolar disorder. Topamax has been investigated as a treatment for obesity and binge eating, as well as alcoholism. In 2004, the FDA approved generic versions of Topamax.
In the treatment of epilepsy, Topamax has been used by about 4 million people worldwide. Topamax can be used alone, or with other antiepileptic medications. Topamax is usually taken twice a day for epilepsy.
In the years since receiving FDA approval for the treatment of migraines, Ortho-McNeil has promoted it heavily. Topamax is touted as a way to stop migraines from occurring, and it is taken daily to prevent their occurrence.
Topamax has become one of the most widely prescribed drugs for migraines, which affects almost 30 million Americans. Women are three times more likely to suffer from migraines than men; women in their childbearing years are particularly vulnerable.
The most common Topamax side effects include a change in taste and feelings of pins and needles in the head and extremities. Less common side effects include cognitive deficiency (particularly word-finding difficulty); difficulty understanding or understanding concepts; grogginess; lethargy; kidney stones, impairment of fine motor skills; vision abnormality and transient or permanent vision loss; severe eye pain; weight loss; breast pain; abdominal pain; intense sweating; menstrual disorder; taste changes; pharyngitis; sinusitis; diplopia; rash; leukopenia; fatigue; dizziness; insomnia; anxiety; depression; paresthesia; diarrhea; nausea; dyspepsia; constipation; dry mouth; and dysmenorrhea.
In July 2008, researchers in Britain shed new light on another possible Topamax side effect - birth defects. A study conducted at the Royal Group of Hospitals in Belfast, Northern Ireland, looked at 203 epileptic women who became pregnant while taking Topamax. The chances that women in the study would give birth to a child with a birth defect increased by as much as 14-fold. The risk for birth defects was especially high in women who took Topamax in combination with another epilepsy drug, valproate.
Of the 178 live births that occurred, three babies whose mothers took Topamax alone and 13 whose mothers took Topamax along with other anti-epilepsy drugs had major birth defects. Four of the babies had cleft palates or cleft lips, which was 11 times higher than would be expected among women not taking epilepsy medication. Four male babies had genital birth defects, with two of these classified as major birth defects. Minor defects included a hole above the buttocks, a flattened head, toe webbing, clicky hips and immature hip joints.
It has long been known that drugs that treat epilepsy are linked to an increased risk of birth defects. The researchers said that the birth defect rate associated with Topamax in their study was in line with those of other anti-seizure drugs, though a larger study is needed to draw definitive conclusions. However, more birth defects occurred in women taking Topamax along with the drug valproate, or valproic acid, than in women taking other epilepsy drugs or other Topamax drug combinations.
The American Academy of Neurology recommends that women with epilepsy considering pregnancy take only one drug, if possible, to control seizures and that they take epilepsy drugs in the lowest effective dosages.
“More research needs to be done to confirm these results, especially since it was a small study,” said John Craig, of the Royal Group of Hospitals in Belfast, Northern Ireland. Craig said risk of birth defects may be different for women taking the drugs to control migraine but they should still be monitored carefully.
“But these results should also get the attention of women with migraine and their doctors, since topiramate is also used for preventing migraine, which is an even more common condition that also occurs frequently in women of childbearing age,” Craig said.
Women of child-bearing age who use Topamax for treatment of epilepsy face a dilemma if they wish to become pregnant, or if they do become pregnant. While Topamax does appear to increase the risk of birth defects, epileptic seizures also increase the risk of fetal harm. In this situation, the risk of birth defects from Topamax must be weighed against the risk to a baby posed by seizures.
The use of Topamax for migraines, however, far outpaces the use of the drug for epilepsy. Migraines are far more common among women than men, and they are most common in women of childbearing age. The shear numbers of women taking Topamax indicates that thousands of unborn babies could be at risk for developing birth defects from this drug.
The researchers involved in the British Topamax study have called for more investigation of this issue. In the meantime, epileptic women taking Topamax should speak with their doctors if they are planning a pregnancy, or become pregnant. Woman using Topamax for migraines should consider an alternative treatment if they plan to conceive.
