Anti-epileptic drugs in pregnancy: current safety and other issues

Birth defects and epilepsy medication

Epilepsy is one of the most common neurological problems in pregnancy. Approximately one in 200 pregnancies is to a woman with epilepsy taking antiepileptic drugs. For the majority of women, pregnancy proceeds without any apparent difficulties but there is growing evidence of an increased risk of major malformations and later cognitive problems in children exposed to antiepileptic drugs in utero. This review summarizes the available evidence for these risks and examines the implications of these in the counseling and treatment of women with epilepsy.

The course and outcome of pregnancy and neonatal situation in epileptic women

Background:

Epilepsy is a rare neurologic disorder during pregnancy. Despite its rarity, it could cause different clinical problems in this natural phenomenon of a woman's life. The aim of this study was to evaluate and compare the course of pregnancy and labor and their outcome in epileptic and healthy women.

Materials and Methods:

This study was performed during years 2009--2011 in Alzahra and Beheshti hospitals affiliated to Isfahan University of Medical Sciences. A total of 51 pregnant women, who were known cases of epilepsy and were on antiepileptic drugs treatment for at least 3 months, were compared with 47 matched healthy pregnant women without epilepsy. They were followed before and during their pregnancy in several visits and all of their neurologic and obstetric information were collected. For statistical analysis of continuous variables, the t-test was used. The chi-square test was used for dichotomous variables.

Results:

The rate of monotherapy was more than polytheraphy especially during the pregnancy. The epileptic attacks stopped in majority of patients during the pregnancy. Vaginal bleeding (P=0.020) and abortion (P=0.015) were significantly more frequent among epileptic mothers. The gestational age was lower meaningfully (P= 0.010) in epileptic patients’ neonates and the first minute Apgar score was lower in these babies too (P=0.028).

Conclusions:

Antiepileptic drugs could have some unsuitable effects on pregnancy course especially by increasing the rate of abortion, preterm labor, and vaginal bleeding. Their adverse effects on neonates’ health could not be neglected.

Development and implementation of an adolescent epilepsy transition clinic

This article describes the collaborative development of a nurse-led transition clinic within the Comprehensive Epilepsy Program at the Stollery Children's Hospital and at the University of Alberta Hospital. Developed in 2005, our program has been instrumental in assisting 97 teens and their parents' transition from pediatric to adult epilepsy care. Through our Adolescent Epilepsy Transition Clinic, we address concerns expressed by teens and their parents when shifting from pediatric to adult healthcare services, including fear of the unknown, change in appointment location, loss of established relationships, and anticipated decrease in the quality of care posttransition. We also address concerns of adult and pediatric healthcare providers related to the adolescents' working knowledge of how their particular type of epilepsy and its management interact with typical adolescent developmental challenges and future career and lifestyle choices. The results from a process evaluation are presented and offer new insights for improving adolescent transition.

Effect of anti-epileptic drugs in pregnancy and teratogenesis

Epilepsy raises special concern in women during pregnancy. Antiepileptic drugs are known to induce major and minor malformations in the foetus. Aim of the study was to find an association between maternal serum alpha fetoprotein levels, foetal abnormalities and antiepileptic drugs mediated teratogenicity. Maternal serum alpha feto protein levels, kidney and liver function tests in age matched normal pregnant women and seizure free epileptic pregnant women during 12-14 weeks of gestation were estimated. Cases were subjected to ultrasonography at 11(th)-14(th) week of pregnancy and again at 20(th) week of pregnancy. maternal serum alfa feto protein was assayed by a specific Electro Chemiluminescence Immuno Assay test. There was no significant difference in kidney and liver function tests in cases as compared to controls. There were elevated levels of alpha feto protein in cases as compared to controls but this was not statistically significant. No anomalies were detected in ultrasound reports. Most women had normal full term delivery with healthy children but of low birth weight. No correlation was seen between maternal serum alfa feto protein levels and antiepileptic drug leading to teratogenesis.

Pharmacotherapy of epilepsy: new armamentarium, new issues

Since 1990 there have been over ten antiepileptic drugs (AEDs) approved for the therapy of epilepsy. These agents have a new spectrum of efficacy and novel adverse effects, some totally unexpected. They also represent an enormous escalation of costs. Few have been subjected to head-to-head comparisons in monotherapy against established AEDs. The aim of therapy is to eliminate rather than to reduce seizure manifestations. Many traditional agents have been phased out due to poor tolerability. New epilepsy syndromes and genetic contributions to epilepsy have been refined. Special considerations apply to various classes of sufferers such as the elderly, women of childbearing age, and sufferers with concomitant disorders, treated with medications capable of drug interactions. There is a recognition of the value of slow introduction, a preference for monotherapy, recognition of the effects of AEDs on hormones and reproductive function and effects on the fetus exposed to AEDs in utero, comprising physical malformations and effects on cognitive development. A balance between efficacy and safety is pivotal, as every preference about the initial pharmacotherapy of epilepsy and subsequent polytherapy has its protagonists. With improvement in diagnostic techniques and new therapeutic modalities it is likely that in the future, pharmacogenomics and an understanding of pharmacoresistance may influence drug selection for individual patients with epilepsy.

Therapeutic monitoring of antiepileptic drugs during pregnancy and in the postpartum period: is it useful?

As in all patient populations, epilepsy is common in pregnant women. Consequently, approximately 1 in 200 pregnancies is exposed to antiepileptic drugs (AEDs). Although exposure to AEDs in utero has been associated with an increased risk of major fetal malformations, most women with epilepsy require medication throughout pregnancy, since seizures themselves may be potentially harmful not only for the mother but also for the developing fetus. Physiological changes during pregnancy result in a reduction in the serum concentrations of most AEDs, particularly in late pregnancy. Changes in protein binding lead to a greater reduction in total than free (active) drug concentrations. Pharmacokinetic changes in pregnancy show interindividual variability and are not well understood for most newer AEDs. However, recent studies have shown that changes in lamotrigine clearance are particularly marked, with increases in each trimester and a significant fall in plasma concentrations, leading to consequent breakthrough seizures in some women. Concentrations may then rise precipitously after delivery, leading to symptoms of lamotrigine toxicity. Therapeutic drug monitoring could theoretically guide adjustment of AED dosage to achieve good seizure control while minimising fetal exposure, although there are several limitations to such monitoring. Firstly, there are wide interindividual variations in serum drug concentrations, with seizure control often correlating poorly with a given therapeutic range. Secondly, therapeutic ranges have not been well defined for newer AEDs and their measurement is often not always available. Thirdly, for highly protein-bound drugs, although measurement of free drug concentrations may more accurately reflect drug availability during pregnancy than total drug concentrations, assays for this are not always available and may be unreliable. Thus, it may be useful, prior to pregnancy, to establish the total and free drug concentrations required to achieve optimal seizure control in a given individual. Regular monitoring of AEDs has been advocated in each trimester and shortly after delivery, with adjustment of dosage to avoid seizure precipitation during pregnancy or symptoms of toxicity after birth. More frequent monitoring has been recommended for lamotrigine. However, aggressive drug monitoring of any AED has yet to be proven to be effective in improving seizure control or care. Furthermore, higher doses may be associated with a greater potential for teratogenicity and it is not yet known whether longer term adverse effects may be related to in utero exposure in the latter half of pregnancy. There is limited evidence about the relationship of maternal serum drug concentrations and teratogenicity. While there is a theoretical role for therapeutic drug monitoring in improving the risk-to-benefit ratio of AED therapy during pregnancy, there are many practical limitations. Future work is needed to clarify its role in improving seizure control during pregnancy and identifying serum drug concentrations that may be considered safe for fetal exposure.

Foetal malformations and seizure control: 52 months data of the Australian Pregnancy Registry

The Australian Pregnancy Registry, affiliated European Register of Antiepileptic drugs in Pregnancy (EURAP), recruits informed consenting women with epilepsy on treatment with antiepileptic drugs (AEDs), those untreated, and women on AEDs for other indications. Enrolment is considered prospective if it has occurred before presence or absence of major foetal malformations (FMs) are known, or retrospective, if they had occurred after the birth of infant or detection of major FM. Telephone Interviews are conducted to ascertain pregnancy outcome and collect data about seizures. To date 630 women have been enrolled, with 565 known pregnancy outcomes. Valproate (VPA) above 1100 mg/day was associated with a significantly higher incidence of FMs than other AEDs (P < 0.05). This was independent of other AED use or potentially confounding factors on multivariate analysis (OR = 7.3, P < 0.0001). Lamotrigine (LTG) monotherapy (n = 65), has so far been free of malformations. Although seizure control was not a primary outcome, we noted that more patients on LTG than on VPA required dose adjustments to control seizures. Data indicate an increased risk of FM in women taking VPA in doses >1100 mg/day compared with other AEDs. The choice of AED for pregnant women with epilepsy requires assessment of balance of risks between teratogenicity and seizure control.

Community-based, prospective, controlled study of obstetric and neonatal outcome of 179 pregnancies in women with epilepsy

PURPOSE

This study evaluated obstetric and neonatal outcome in a community-based cohort of women with active epilepsy (WWAE) compared with the general pregnant population receiving modern obstetric care.

METHODS

We reviewed the total population who gave birth between January 1989 and October 2000 at Kuopio University Hospital. Obstetric, demographic, and epilepsy data were collected prospectively from 179 singleton pregnancies of women with epilepsy and from 24,778 singleton pregnancies of unaffected controls. The obstetric data from the pregnancy register was supplemented with detailed neurologic data retrieved from the medical records. The data retrieved were comprehensive because of a follow-up strategy according to a predecided protocol.

RESULTS

During pregnancy, the seizure frequency was unchanged, or the change was for the better in the majority (83%) of the patients. We found no significant differences between WWAE and controls in the incidence of preeclampsia, preterm labor, or in the rates of caesarean sections, perinatal mortality, or low birth weight. However, the rate of small-for-gestational-age infants was significantly higher, and the head circumference was significantly smaller in WWAE. Apgar score at 1 min was lower in children of WWAE, and the need for care in the neonatal ward and neonatal intensive care were increased as compared with controls. The frequency of major malformations was 4.8% (-0.6-10.2%; 95% confidence interval) in the 127 children of WWAE.

CONCLUSIONS

Pregnancy course is uncomplicated and neonatal outcome is good in the majority of cases when a predecided protocol is used for the follow-up of WWAE in antenatal and neurologic care. Long-term follow-up of the neurologic and cognitive development of the children of WWAE is still needed.

Malformation risks of antiepileptic drugs in pregnancy: a prospective study from the UK Epilepsy and Pregnancy Register

OBJECTIVE

To assess the relative risk of major congenital malformation (MCM) from in utero exposure to antiepileptic drug (AEDs).

METHODS

Prospective data collected by the UK Epilepsy and Pregnancy Register were analysed. The presence of MCMs recorded within the first three months of life was the main outcome measure.

RESULTS

Full outcome data were collected on 3607 cases. The overall MCM rate for all AED exposed cases was 4.2% (95% confidence interval (CI), 3.6% to 5.0%). The MCM rate was higher for polytherapy (6.0%) (n = 770) than for monotherapy (3.7%) (n = 2598) (crude odds ratio (OR) = 1.63 (p = 0.010), adjusted OR = 1.83 (p = 0.002)). The MCM rate for women with epilepsy who had not taken AEDs during pregnancy (n = 239) was 3.5% (1.8% to 6.8%). The MCM rate was greater for pregnancies exposed only to valproate (6.2% (95% CI, 4.6% to 8.2%) than only to carbamazepine (2.2% (1.4% to 3.4%) (OR = 2.78 (p<0.001); adjusted OR = 2.97 (p<0.001)). There were fewer MCMs for pregnancies exposed only to lamotrigine than only to valproate. A positive dose response for MCMs was found for lamotrigine (p = 0.006). Polytherapy combinations containing valproate carried a higher risk of MCM than combinations not containing valproate (OR = 2.49 (1.31 to 4.70)).

CONCLUSIONS

Only 4.2% of live births to women with epilepsy had an MCM. The MCM rate for polytherapy exposure was greater than for monotherapy exposure. Polytherapy regimens containing valproate had significantly more MCMs than those not containing valproate. For monotherapy exposures, carbamazepine was associated with the lowest risk of MCM.

Maternal valproate dosage and foetal malformations

OBJECTIVE- To study the possible dose dependence of the foetal malformation rate after exposure to sodium valproate in pregnancy METHODS- Analysis of records of all foetuses in the Australian Registry of Antiepileptic Drugs in Pregnancy exposed to valproate, to carbamazepine, lamotrigine or phenytoin in the absence of valproate, and to no antiepileptic drugs. RESULTS- The foetal malformation rate was higher (P<0.05) in the 110 foetuses exposed to valproate alone (17.1%), and in the 165 exposed to valproate, whether alone or together with the other antiepileptic drugs (15.2%), than in the 297 exposed to the other drugs without valproate (2.4%). It was also higher (P<0.10) than in the 40 not exposed to antiepileptic drugs (2.5%). Unlike the situation for the other drugs, the malformation rate in those exposed to valproate increased with increasing maternal drug dosage (P<0.05). The rate was not altered by simultaneous exposure to the other drugs. Valproate doses exceeding 1400 mg per day seemed to be associated with a more steeply increasing malformation rate than at lower doses and with a different pattern of foetal malformations. CONCLUSIONS- Foetal exposure to valproate during pregnancy is associated with particularly high, and dose-dependent risks of malformation compared with other antiepileptic drugs, and may possibly involve different teratogenetic mechanisms.