Many women suffering from epilepsy become pregnant. In that case proper control and correct attacks prevention is extremely important. Only a few drugs, used in epilepsy treatment are considered to be safe for expectant mothers. The most popular is carbamazepine. There is also a group of drugs with proven negative impact on the developing fetus. On March 2011 one more drug joined this group. It was topiramate, which is used by adults and children over the age of two in therapy of partial seizures, generalized tonic-clonic seizures, unconsciousness, myoclonic, Lennox-Gastaut and Waet syndrome, as well as in the treatment of chronic migraine and obesity.
On 4th March 2011 FDA announced that children of mothers, who were taking topiramate and its generics during the pregnancy, more often suffer from lip and palate clefts. The negative influence of topiramate on human fetus was signalized already in article published in 2008. British researchers found that using of topiramate in the first trimester of pregnancy significantly increases the risk of congenital defects in the fetus. Though the study included only 200 women who become pregnant while taking topiramate, in 16 of 178 born children different malformations were detected, both when topiramate was used in mono, as well as in polytherapy (1). These disturbing results have led the researchers to organize the extensive research on a much wider scale.
Basing on collected data, it was found that prevalence of clefts among fetuses exposed to topiramate as monotherapy in the first trimester of pregnancy is 1,4%, while in the group of offspring of patients taking other antiepileptic drugs varies from 0,38% to 0,55%. Still, this parameter was much lower in healthy women, who do not receive any therapy and it was only 0,07% (2).
Previously topiramate appeared on the list of drugs in C category as a substance showing an adverse effect on the fetus in animal studies but the current knowledge has prompted the FDA agency to reclassify it to category D, due to observed adverse effects on the human embryo. In this situation topiramate may be used during pregnancy only when it is absolutely necessary and the benefits for mother health outweigh potential risk for the child.
Therefore, doctors treating women suffering from epilepsy and taking topiramate in childbearing age should consider replacing it with another, safer drug. If it is impossible due to the increased risk of improper seizure control, woman should be warned of the potential risk to her baby.
Author: Patrycja Marciniak
Bibliography:
1. S. Hunt, A. Russel Topiramate in pregnancy, http://www.neurology.org/content/71/4/272.abstract (13.03.2011)
2. Lowes Robert, Topiramate linked to birth defects, http://www.medscape.com/viewarticle/738432 , (13.03.2011)