This will cover the use of TDM to manage the pharmacokinetic variability due to interactions with oral contraception and the substantial pharmacokinetic changes associated with pregnancy.
At the end of this session the participants will be able to:
- Appreciate the bidirectional interactions that occur between hormonal contraceptive agents and antiepileptic drugs, as well as the clinical implications.
- Identify which AEDs undergo substantial increased clearance with contraceptive hormones and/or pregnancy and to what degree.
- Have a basic understanding of how TDM can be used during preconception, pregnancy and postpartum phases to achieve better maternal and child outcomes.
Optimal treatment of women with epilepsy during the child bearing years requires an understanding of the complex bidirectional interactions between AEDs and sex steroid hormones. A planned pregnancy with good seizure control is the most important factor in achieving healthy maternal and child outcomes. However, many AEDs lower efficacy of hormonal contraceptives via induction of the hepatic cytochrome P-450 system and /or glucuronidation. This commonly allows ovulation and a high proportion of unplanned pregnancies. Conversely, most hormonal contraceptive agents enhance glucuronidation and cause increased clearance of some AEDs, which can result in break-through seizures.
During pregnancy, achieving an optimal balance between seizure control and fetal AED exposure is especially important to lower teratogenic risks. During pregnancy, AED levels decline substantially due to a variety of pharmacokinetic changes, but the degree and time course of change varies by AED and between individuals. Therapeutic drug monitoring to maintain the individual’s target concentration during pregnancy can lower the risk for seizure worsening and lower the risk to the developing fetus. Management of postpartum AED pharmacokinetic changes will also be discussed in the context of possible breastfeeding with continued infant AED exposure.