Changes in Perampanel Pharmacokinetics and Cytochrome P450 3A4 Activity Before, During, and After Pregnancy

This study evaluated perampanel pharmacokinetics and cytochrome P450 3A4 (CYP3A4) activity, assessed using the level of 4β-hydroxycholesterol (4β-OHC) as an endogenous biomarker of CYP3A4, before, during, and after pregnancy in a woman with epilepsy and compared these measurements with those from a control group of nonpregnant women with epilepsy. A 21-year-old pregnant woman was being treated with perampanel (serum concentration: 1120 ng/mL), lacosamide, and lamotrigine. After the first trimester, the lamotrigine concentration decreased markedly; however, the perampanel concentration remained almost unchanged (range, 1130-1320 ng/mL). Similarly, serum 4β-OHC levels did not change during pregnancy (before pregnancy, 78.2 ng/mL; during pregnancy, 62.2-83.2 ng/mL). To compare these measurements with those in nonpregnant women, we enrolled 27 nonpregnant women with epilepsy (age range, 16-40 years). In the control patients, we found a strong negative correlation between the concentration-to-dose ratio of perampanel and the 4β-OHC level ( r = -0.78, P < 0.001). As there was no significant change in CYP3A4 activity, we concluded that the serum perampanel concentration did not change significantly before, during, or after pregnancy. More patients need to be studied to confirm these early results.