Further evidence supporting the safety of two antiseizure medications in pregnancy has come from a new study. Most of the women with epilepsy in the study took either lamotrigine or levetiracetam, or a combination of the two, during their pregnancy.
However, a secondary analysis suggested a possible signal of exposure-dependent effects on child outcomes – worse outcomes with higher exposure levels – with levetiracetam.
The results were presented at the American Academy of Neurology’s 2021 annual meeting.
Additional reassurance
“Our new study adds confidence to the use of lamotrigine and levetiracetam during pregnancy, adding larger numbers with a new cohort. In addition, it provides some preliminary data on some of the other new antiseizure medications, and it is the first study to address the effects of clearance in pregnancy to better assess exposure,” said lead investigator, Kimford J. Meador, MD. “Overall, I am reassured by this data, but there is still a lot that is unknown,” he added.
“Our main results show no difference in verbal index or general conceptual ability scores in children born to women with epilepsy compared to children born to healthy women. This is a big positive message,” Dr. Meador said.
In terms of secondary analysis focusing on exposure levels (dose and blood levels of antiseizure medications), there was no overall signal of harm when looking at the whole group, but when the researchers analyzed the data on individual drugs, they found a “slight signal” toward reduced verbal index scores with increasing exposure levels with levetiracetam. No differences were seen on general conceptual ability.
“In the secondary analysis, there was a marginal signal for exposure levels with levetiracetam, with increased blood levels of the drug associated with reduced verbal index scores,” reported Dr. Meador, professor of neurology and neurological sciences at Stanford (Calif.) University. “We saw some signal in the children when they were 2 years old, and this was still there but not as striking at 3 years old.”
He said these secondary results should be interpreted with extreme caution. “We don’t want to overemphasize these secondary findings, as the primary outcome showed no difference, and there was no effect on exposure levels when looking at all the drugs together. I don’t want to oversimplify this, as I am still not sure whether this is a real association or not,” Dr. Meador commented.
He explained that conducting neurobehavioral tests on 2- and 3-year-olds was very difficult. “It is more of an art form than science, and as the children get older these signals often dissipate. We will know more by the time they are 6, when these tests become easier to conduct,” he said. He also noted that the results would need to be replicated in a different cohort.
“I don’t think these results would change how we manage women during pregnancy in terms of using levetiracetam. It is still a safe drug during pregnancy,” Dr. Meador said.
He pointed out that data on safety in pregnancy is only available for very few antiseizure drugs. “There are over 30 antiseizure medications, but we have adequate data in pregnancy on only a handful. We have data suggesting lamotrigine, levetiracetam, and carbamazepine appear to be relatively safe, and evidence showing phenobarbital and valproate are not safe.”
Antiseizure medications as a class are among the most commonly prescribed teratogenic drugs given to women of childbearing age, Dr. Meador noted. They are used not only for epilepsy but also for many other psychiatric and pain indications, so these results are applicable to quite a broad population, he added.
He pointed out that previous studies did not assess exposure using blood levels, which is important, as clearance of drug increases during pregnancy but varies across antiseizure medications and across individuals on the same drug. “Thus, it is unclear if these changes could obscure exposure-dependent effects. Our present studies assessed blood levels to better measure fetal exposure.”
