Concentrations of Certain Antiseizure Meds Drop During Pregnancy

Dose-normalized concentrations of lamotrigine, levetiracetam, lacosamide, oxcarbazepine, and zonisamide decreased during pregnancy

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FRIDAY, Feb. 25, 2022 (HealthDay News) -- Among pregnant women with epilepsy, dose-normalized concentrations of several antiseizure medications decrease during pregnancy, according to a study published online Feb. 14 in JAMA Neurology.

Page B. Pennell, M.D., from University of Pittsburgh, and colleagues analyzed data from 430 women (aged 16 to 43 years) with epilepsy (326 pregnant participants and 104 nonpregnant control participants) to examine pregnancy-associated concentration changes for several antiseizure medications.

The researchers found that compared with postpartum values, dose-normalized concentrations during pregnancy were decreased by up to 56.1 percent for lamotrigine (15.60 to 6.85 μg/L/mg), 36.8 percent for levetiracetam (11.33 to 7.16 μg/L/mg), 17.3 percent for carbamazepine (11.56 to 7.97 μg/L/mg), 32.6 percent for oxcarbazepine (11.55 to 7.79 μg/L/mg), 30.6 percent for unbound oxcarbazepine (6.15 to 4.27 μg/L/mg), 39.9 percent for lacosamide (26.14 to 15.71 μg/L/mg), and 29.8 percent for zonisamide (40.12 to 28.15 μg/L/mg). Pregnancy dose-normalized median concentrations decreased significantly by week of gestational age compared with dose-normalized concentrations from control participants: carbamazepine, −0.14 μg/L/mg; carbamazepine unbound, −0.04 μg/L/mg; lacosamide, −0.23 μg/L/mg; lamotrigine, −0.20 μg/L/mg; levetiracetam, −0.06 μg/L/mg; oxcarbazepine, −0.14 μg/L/mg; oxcarbazepine unbound, −0.11 μg/L/mg; and zonisamide, −0.53 μg/L/mg.

"Results of this study suggest the need for higher doses of several antiseizure medications during pregnancy and support therapeutic drug monitoring beginning early in pregnancy," the authors write.

Several authors disclosed financial ties to the pharmaceutical industry.

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