In utero antiepileptic drug exposure: fetal death and malformations

Atresia of the aortic arch, with a collateral artery from the right subclavian artery supplying the descending aorta

An infant of 2 months presented with absence of the femoral pulses, albeit with no signs of cardiac failure. The mother was known to have ingested Valproate during pregnancy. Echocardiography showed the aortic arch to be interrupted between the left common carotid and left subclavian arteries, so-called type B interruption, in the setting of an intact ventricular septum. Angiography, and multislice computed tomography, revealed the descending aorta to be supplied by a collateral artery originating from the right subclavian artery. Corrective surgery was successfully performed, but revealed an atretic segment of the arch at the site of interruption of flow.

Epilepsy in women: special considerations for adolescents

Adolescence is a time of many changes. It is a time of growing independence, physical and emotional change, accompanied by social insecurity. Girls tend to enter puberty ahead of their male peers, growing and changing physically. Our culture tells adolescents that they are still immature, but their bodies are saying otherwise. The adolescents are also becoming aware of themselves as individuals, separate from their parents, and are presented with the challenges of independent thinking and action. If, in the midst of all of these changes, an adolescent is given the diagnosis of a chronic disease such as epilepsy, there is an additional burden. Often the adolescent must go through a variety of emotions, including shame, denial, anger, and sadness. Our role as medical providers is to provide some perspective to the illness and help guide our adolescent patient through the tumultuous emotions of grieving and acceptance. We must provide a foundation of assistance and emotional support, as well as medical knowledge. With a firm but compassionate hand, we can help them cope with their disorder. In this chapter, Drs. Haut and Zupanc explore some of the unique considerations in adolescent women with epilepsy. The first part of the chapter deals with the epidemiologic diagnosis of epilepsy in adolescence, the effect of epilepsy on reproductive health, hormonal influences on epilepsy (including catamenial seizures), and the effects of antiepileptic drugs (AEDs) on hormones, contraception, and bone health. In the second part of the chapter, we deal with the very real psychosocial issues and comorbidities of epilepsy, including quality of life, school performance, depression, migraine headaches, social stigma, and lifestyle changes. In the final section, the authors suggest strategies for clinical patient management.

Lamotrigine in pregnancy: clearance, therapeutic drug monitoring, and seizure frequency

OBJECTIVE

To characterize the magnitude and course of alterations in total and free lamotrigine (LTG) clearance (Cl) during pregnancy and the postpartum period, to assess the impact of therapeutic drug monitoring (TDM) on seizure frequency, to determine the ratio to individual target LTG concentration that is associated with increased seizure risk, and to evaluate maternal postpartum toxicity.

METHODS

A cohort of women were enrolled before conception or during pregnancy in this prospective, observational study. Visits occurred every 1 to 3 months with review of seizure and medication diaries, examination, and blood sampling. Total and free LTG Cls were calculated. Individualized target concentrations were used for TDM. The ratio to target concentration (RTC) was compared between patients with and without increased seizures. A receiver operating characteristic curve determined the threshold RTC that best predicts increased seizure frequency.

RESULTS

Analysis of 305 samples in 53 pregnancies demonstrated increased total and free LTG Cl in all trimesters above nonpregnant baseline (p < 0.001), with peak increases of 94% and 89% in the third trimester. Free LTG Cl was higher in white compared with black women (p < 0.05). Increased seizure frequency (n = 36 women with epilepsy) in the second trimester was associated with a lower RTC (p < 0.001), and RTC < 0.65 was a significant predictor of seizure worsening. An empiric postpartum taper reduced the likelihood of maternal LTG toxicity (p < 0.05) (n = 27). Newborn outcomes were similar to the general population (n = 52).

CONCLUSIONS

These novel data contribute to a rational treatment plan and dosing paradigm for lamotrigine use during pregnancy, parturition, and the postpartum period.

Postnatal concerns in children born to women with epilepsy

Infants born to mothers with epilepsy are at substantial risk for neurocognitive and behavioral disorders. Although exposure of the child to antiepileptic drugs (AEDs) during pregnancy and postnatally through breast milk has been implicated in disorders of higher cortical function, there have been relatively few clinical or animal studies examining the long-term effects of AEDs on cognition in the developing brain. In the limited animal studies done thus far, drug-specific effects on cognitive function have been identified. Phenobarbital, in particular, has been found to lead to adverse cognitive outcomes, whereas the newer AEDs have generally had more favorable outcomes. Although the pathophysiological mechanisms responsible for these deficits remain largely unknown, there is evidence that AEDs can adversely effect neuronal proliferation and migration, and increase apoptosis. While animal studies can provide valuable information regarding mechanism of AED-induced developmental pathology, they do not provide insight into cortical functions unique to humans, such as speech and language. Understanding the full spectrum of AED-induced effects on the developing brain will require both rigorous basic science and clinical studies.

Subcutaneous histamine versus sodium valproate in migraine prophylaxis: a randomized, controlled, double-blind study

Histamine has a selective affinity for H3-receptors and it may specifically inhibit the neurogenic edema response involved in migraine pathophysiology. The objective of this study was to evaluate the therapeutic potential of subcutaneous administration of histamine in migraine prophylaxis, compared with oral administration of sodium valproate, in an open clinical trial. Ninety-two patients with migraine were selected under criteria established by the International Headache Society and enrolled in a 12-week double-blind controlled clinical trial to evaluate the efficacy of subcutaneous administration of histamine (1-10 ng twice a week; n = 46) compared with oral administration of sodium valproate (500 mg daily dose; n = 46). The variables studied were headache intensity, frequency, duration, analgesic intake and migraine disability assessment (MIDAS). Two-tailed Student's t- test was used to compare means and the Mann-Whitney U and anova tests were used. The data collected during the 4th, 8th and 12th weeks of treatment revealed that histamine caused a significantly greater reduction (P < 0.001) in intensity and duration of migraine attacks as well as in analgesic intake. No difference was detected in the frequency of attacks or in MIDAS. The present study provides evidence of the superior efficacy of histamine applied subcutaneously in migraine prophylaxis when compared with sodium valproate taken orally. Subcutaneously applied histamine may represent a novel and effective therapeutic alternative in resistant migraine patients.

Emerging drugs for epilepsy

Epilepsy affects < or = 1% of the world's population. Antiepileptic drugs (AEDs) are the mainstay of treatment, although more than a third of patients are not rendered seizure free with existing medications. Uncontrolled epilepsy is associated with increased mortality and physical injuries, and a range of psychosocial morbidities, posing a substantial economic burden on individuals and society. Limitations of the present AEDs include suboptimal efficacy and their association with a host of adverse reactions. Continued efforts are being made in drug development to overcome these shortcomings employing a range of strategies, including modification of the structure of existing drugs, targeting novel molecular substrates and non-mechanism-based drug screening of compounds in traditional and newer animal models. This article reviews the need for new treatments and discusses some of the emerging compounds that have entered clinical development. The ultimate goal is to develop novel agents that can prevent the occurrence of seizures and the progression of epilepsy in at risk individuals.

Women with epilepsy: hormonal issues from menarche through menopause

Epilepsy is a multilayered disorder complicated by numerous comorbid conditions and hormonal changes. More than 1.5 million girls and women with epilepsy face side effects that are compounded at different ages by menstruation, fertility, pregnancy, fetal health, bone health, and other health issues. Changes in hormonal balance during maturation, from menarche through menopause, affect seizure thresholds and antiepileptic drugs, and vice versa. This overview provides physicians with a background on the multiple issues relevant to women of all ages in the reproductive years, including those planning to conceive and those who are pregnant, and beyond the childbearing years.

Antiepileptic medication during pregnancy: does fetal genotype affect outcome?

Congenital abnormalities and impaired development in childhood are attributable to fetal exposure to antiepileptic drugs (AEDs). Pregnancy registries set up to obtain information about the potential risks of fetal exposure to AEDs, in particular major congenital malformations (MCMs), suggest that valproate exposure increases the frequency of congenital malformations more than other AEDs. Furthermore, follow-up studies have drawn attention to cognitive impairments in later childhood after prenatal exposure to valproate. Fetal exposure to AEDs may be influenced by drug transporting proteins in the placenta, including P-glycoprotein (P-gp), multidrug resistance protein (MRP) 1, and breast cancer resistance protein (BCRP). Their location in the syncytiotrophoblast plasma membrane, at the interface of the maternal and fetal circulations, allows these transport proteins to efflux xenobiotics back to the mother and offers the fetus protection from medications taken during pregnancy. Genetic variations in the expression and activity of these transport proteins may influence fetal exposure to AEDs and thus the risk of teratogenicity. Identification of a hierarchy of haplotypes ranging from susceptible to protective of congenital abnormalities could assist genetic counseling, in assessing fetal risks from exposure to AEDs.

Teratogenicity of lamotrigine

QUESTION

One of my female patients has epilepsy and is currently receiving lamotrigine monotherapy. She has recently found that she is 6 weeks pregnant and is concerned about possible side effects of lamotrigine on her fetus. How should I advise her and should I switch to another antiepileptic drug?

ANSWER

Lamotrigine (LTG) has not been associated with an increased risk for major malformations in monotherapy in most available studies. Risk of major malformations has been suggested when LTG was taken in doses higher than 200 mg/d and when clefts not caused by any known syndrome have been associated with LTG treatment. Therefore, safety for the fetus cannot yet be proven or rejected, although the drug does not appear to be a major human teratogen.

The adverse effects of antiepileptic drugs in children

Efficacy of antiepileptic drugs (AEDs) are often equivalent, hence selection of an AED is often determined by the adverse effects (AEs). The development of neurocognitive AEs is almost inevitable with use of AEDs, especially in high-risk groups. Teratogenesis with major or minor malformations is of great concern during the first trimester of pregnancy, but an increasing body of information suggests that potential neurocognitive developmental delay may also occur with use of AEDs in the latter part of pregnancy. Decreased bone mineral density has been found in adults and children receiving both enzyme-inducing AEDs and valproate, an enzyme-inhibiting drug. AEDs may influence the lipid profile, body weight, reproductive, hormonal and other endocrine functions, and sleep architecture. There are age-specific AEs related to pharmacokinetic differences that have been highlighted in this review with emphasis on the pediatric population. A classification of AEs using different parameters is also included.

In utero exposure to antiepileptic drugs: teratogenicity and neonatal morbidity

Clinical studies have extensively documented the various risks posed by in utero exposure to antiepileptic drugs (AEDs). However, it is difficult to sort out the extent to which any given AED is responsible for a particular outcome, given the disparities in patients taking the drugs, their type and severity of epilepsy, and the various possible AEDs, as well as the vast number of outcomes that could be assessed. This review focuses on AED exposure during pregnancy and how it affects the risks of neonatal morbidity and major congenital malformations.

In utero antiepileptic drug exposure

Until recently, retrospective reports and small prospective studies have suggested that all antiepileptic drugs could be associated with teratogenicity. Over the last year alone, several important reports have been released from North America, Australia and the UK. The recently released Neurodevelopmental Effects of Antiepileptic Drugs study combining cohorts from the USA and the UK enrolled women from 1999-2004 and extended these results to include not only risks for major malformations, but also cognitive problems independent of anatomical consequences. In addition, future plans to describe the postnatal manifestations during the first 6 years of life may shed some light on later effects, not previously identified. Information from worldwide pregnancy registries are now reporting results that are alarmingly similar with respect to the increased risk of pregnancies born to women with epilepsy, consistently demonstrating greater degrees of major congenital malformations with the use of valproate, polytherapy and high-dose antiepileptic drugs administered within the first trimester of pregnancy.

Seizures and Antiepileptic Drugs: Does Exposure Alter Normal Brain Development?

Seizures and antiepileptic drugs (AEDs) affect brain development and have long-term neurological consequences. The specific molecular and cellular changes, the precise timing of their influence during brain development, and the full extent of the long-term consequences of seizures and AEDs exposure have not been established. This review critically assesses both the basic and clinical science literature on the effects of seizures and AEDs on the developing brain and finds that evidence exists to support the hypothesis that both seizures and antiepileptic drugs influence a variety of biological process, at specific times during development, which alter long-term cognition and epilepsy susceptibility. More research, both clinical and experimental, is needed before changes in current clinical practice, based on the scientific data, can be recommended.

2005 AES Annual Course: Evidence Used to Treat Women with Epilepsy

Although most female-specific considerations for treatment of epilepsy cannot be answered by Class I evidence, significant progress in our knowledge base has occurred in the past few years. Open-label studies of progesterone supplementation showed promising results; an ongoing randomized trial may provide definitive evidence for therapeutic use of progesterone in women. A randomized trial of hormone replacement therapy demonstrated a dose-related increase in seizure frequency in postmenopausal women with epilepsy. The use of different AED regimens during pregnancy cannot be explored with randomized, controlled trials; we must rely on the best available evidence from ongoing observational studies. The consistent findings of large prospective pregnancy registries reveal a consistent pattern of amplified risk for major congenital malformations in pregnancies exposed to valproate. These registries have also highlighted the concern for the effect of shifting hormones on AED concentrations. An increased frequency of seizures during pregnancy has been noted with lamotrigine (LTG) and oxcarabazepine, both of which undergo glucuronidation. Other studies have demonstrated an increased clearance of LTG during pregnancy and with exogenous estrogen use. It may be prudent to closely monitor serum concentrations of these AEDs with hormonal changes. An increased risk for neurodevelopmental consequences has been demonstrated for the fetus exposed to AED polytherapy, valproic acid, or frequent maternal convulsive seizures. Preliminary information about breastfeeding with LTG and levetiracetam is available. These newly released findings provide the tools to begin to practice evidence-based medicine when treating our female patients during their reproductive and postmenopausal years.

Antiepileptic drugs and neurodevelopment

Clinical studies have documented the teratogenic potential of antiepileptic drugs (AEDs). More recent cohort studies have been trying to sort out which AEDs impose the highest risk of teratogenicity. Currently, there is evidence demonstrating an increased risk of major congenital malformations (MCMs) for valproate, phenobarbital, and polytherapy during pregnancy. Based on the current data from multiple studies, the risk for valproate is the highest. Additional studies are needed to fully delineate if differences exist for other AEDs, especially the newer AEDs. However, although MCMs are easy to recognize and have been shown to be more common after in utero exposure to AEDs, there are insufficient data regarding their long-term effects on cognition and behavior in exposed children. Although most children born to women with epilepsy are healthy, in recent years there has been increasing awareness of the long-term effects of in utero exposure to AEDs. Recent discovery of neuronal apoptosis following in utero AED exposure in animals during a period that corresponds to the third trimester and early infancy in humans raises further concerns. Prospective clinical studies seem necessary in order to better understand the long-term neurodevelopmental effects of in utero exposure to AEDs.