Topamax Birth Defect Risk Complicated by Interaction with Birth Control Pills

Women taking <"">Topamax should be aware that its active ingredient, topiramate, may inhibit the effectiveness of birth control pills. It is especially important that women of child-bearing age be aware of this Topamax side effect, due to its association with birth defects, including oral clefts.

Studies have shown that among women who take Topamax and birth control pills, the rate of contraceptive failure could be as high as 7 percent. These studies indicate that drugs like Topamax increase the metabolism of estrogen and progesterone, leading to failure of hormone-based birth control.

Women of child bearing age who take Topamax are advised to use additional forms of birth control to safeguard against birth control pill failure. Forms of non-hormone based birth control that are not affected by Topamax include condoms, copper IUD, sponge or spermicides.

Earlier this year, the U.S. Food & Drug Administration (FDA) moved Topamax from Pregnancy Category C to Pregnancy Category D, after data indicated that women taking the drug in the early months of pregnancy face a higher risk of having a baby with an oral cleft. The Pregnancy Category D designation means that there is positive evidence of human fetal risk based on human data, but potential benefits in pregnant women may outweigh risks in certain situations.

According to the FDA, data from the North American Antiepileptic Drug (AED) Pregnancy Registry indicated that infants exposed to Topamax as a single therapy during the first trimester of pregnancy experienced a 1.4 percent prevalence of oral clefts, compared with a prevalence of 0.38 percent – 0.55 percent in infants exposed to other antiepileptic drugs. Infants of mothers who did not have epilepsy and were not being treated with other antiepileptic drugs had a prevalence of 0.07 percent.

Oral clefts are birth defects that occur when parts of the lip or palate do not completely fuse together early in the first trimester of pregnancy, a time when many women do not know they are pregnant. They can range from a small notch in the lip to a groove that runs into the roof of the mouth and nose, possibly leading to problems with eating, talking, and to ear infections.

Topamax may also be linked to other birth defects. According to the FDA’s Adverse Event Report database, there have been a total of 244 reports made to the agency of injuries to children believed to be associated with the use of Topamax. Of those, more than 100 involved possible Topamax birth defects, including 29 oral clefts, 29 limb malformations, 27 heart defects, 26 reports of other congenital defects, 23 cranio-facial defects, 15 reports of spina bifida/spinal malformations, and 5 reports of persistent pulmonary hypertension of the newborn (PPHN).

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