Teratogenicity of antiepileptic drugs: analysis of possible risk factors

Management of epilepsy during pregnancy and lactation

Epilepsy is a group of neurological diseases characterized by susceptibility to recurrent seizures. Antiseizure medications (ASMs) are the mainstay of treatment, but many antiseizure medications with variable safety profiles have been approved for use. For women with epilepsy in their childbearing years, the safety profile is important for them and their unborn children, because treatment is often required to protect them from seizures during pregnancy and lactation. Since no large randomized controlled trials have investigated safety in this subgroup of people with epilepsy, pregnancy registries, cohort and case-control studies from population registries, and a few large prospective cohort studies have played an important role. Valproate, in monotherapy and polytherapy, has been associated with elevated risk of major congenital malformations and neurodevelopmental disorders in children born to mothers who took it. Topiramate and phenobarbital are also associated with elevated risks of congenital malformations and neurodevelopmental disorders, though the risks are lower than those of valproate. Lamotrigine and levetiracetam are relatively safe. Insufficient data exist to reach strong conclusions about the newest antiseizure medications such as eslicarbazepine, perampanel, brivaracetam, cannabidiol, and cenobamate. Besides antiseizure medications, other treatments such as vagal nerve stimulation, responsive neurostimulation, and deep brain stimulation are likely safe. In general, breastfeeding does not appear to add any additional long term risks to the child. Creative ways of optimizing registry enrollment and data collection are needed to enhance patient safety.

Monotherapy treatment of epilepsy in pregnancy: congenital malformation outcomes in the child

BACKGROUND

Prenatal exposure to certain anti-seizure medications (ASMs) is associated with an increased risk of major congenital malformations (MCM). The majority of women with epilepsy continue taking ASMs throughout pregnancy and, therefore, information on the potential risks associated with ASM treatment is required.

OBJECTIVES

To assess the effects of prenatal exposure to ASMs on the prevalence of MCM in the child.

SEARCH METHODS

For the latest update of this review, we searched the following databases on 17 February 2022: Cochrane Register of Studies (CRS Web), MEDLINE (Ovid, 1946 to February 16, 2022), SCOPUS (1823 onwards), and ClinicalTrials.gov, WHO International Clinical Trials Registry Platform (ICTRP). No language restrictions were imposed.

SELECTION CRITERIA

We included prospective cohort controlled studies, cohort studies set within pregnancy registries, randomised controlled trials and epidemiological studies using routine health record data. Participants were women with epilepsy taking ASMs; the two control groups were women without epilepsy and untreated women with epilepsy.

DATA COLLECTION AND ANALYSIS

Five authors independently selected studies for inclusion. Eight authors completed data extraction and/or risk of bias assessments. The primary outcome was the presence of an MCM. Secondary outcomes included specific types of MCM. Where meta-analysis was not possible, we reviewed included studies narratively.

MAIN RESULTS

From 12,296 abstracts, we reviewed 283 full-text publications which identified 49 studies with 128 publications between them. Data from ASM-exposed pregnancies were more numerous for prospective cohort studies (n = 17,963), than data currently available for epidemiological health record studies (n = 7913). The MCM risk for children of women without epilepsy was 2.1% (95% CI 1.5 to 3.0) in cohort studies and 3.3% (95% CI 1.5 to 7.1) in health record studies. The known risk associated with sodium valproate exposure was clear across comparisons with a pooled prevalence of 9.8% (95% CI 8.1 to 11.9) from cohort data and 9.7% (95% CI 7.1 to 13.4) from routine health record studies. This was elevated across almost all comparisons to other monotherapy ASMs, with the absolute risk differences ranging from 5% to 9%. Multiple studies found that the MCM risk is dose-dependent. Children exposed to carbamazepine had an increased MCM prevalence in both cohort studies (4.7%, 95% CI 3.7 to 5.9) and routine health record studies (4.0%, 95% CI 2.9 to 5.4) which was significantly higher than that for the children born to women without epilepsy for both cohort (RR 2.30, 95% CI 1.47 to 3.59) and routine health record studies (RR 1.14, 95% CI 0.80 to 1.64); with similar significant results in comparison to the children of women with untreated epilepsy for both cohort studies (RR 1.44, 95% CI 1.05 to 1.96) and routine health record studies (RR 1.42, 95% CI 1.10 to 1.83). For phenobarbital exposure, the prevalence was 6.3% (95% CI 4.8 to 8.3) and 8.8% (95% CI 0.0 to 9277.0) from cohort and routine health record data, respectively. This increased risk was significant in comparison to the children of women without epilepsy (RR 3.22, 95% CI 1.84 to 5.65) and those born to women with untreated epilepsy (RR 1.64, 95% CI 0.94 to 2.83) in cohort studies; data from routine health record studies was limited. For phenytoin exposure, the prevalence of MCM was elevated for cohort study data (5.4%, 95% CI 3.6 to 8.1) and routine health record data (6.8%, 95% CI 0.1 to 701.2). The prevalence of MCM was higher for phenytoin-exposed children in comparison to children of women without epilepsy (RR 3.81, 95% CI 1.91 to 7.57) and the children of women with untreated epilepsy (RR 2.01. 95% CI 1.29 to 3.12); there were no data from routine health record studies. Pooled data from cohort studies indicated a significantly increased MCM risk for children exposed to lamotrigine in comparison to children born to women without epilepsy (RR 1.99, 95% CI 1.16 to 3.39); with a risk difference (RD) indicating a 1% increased risk of MCM (RD 0.01. 95% CI 0.00 to 0.03). This was not replicated in the comparison to the children of women with untreated epilepsy (RR 1.04, 95% CI 0.66 to 1.63), which contained the largest group of lamotrigine-exposed children (> 2700). Further, a non-significant difference was also found both in comparison to the children of women without epilepsy (RR 1.19, 95% CI 0.86 to 1.64) and children born to women with untreated epilepsy (RR 1.00, 95% CI 0.79 to 1.28) from routine data studies. For levetiracetam exposure, pooled data provided similar risk ratios to women without epilepsy in cohort (RR 2.20, 95% CI 0.98 to 4.93) and routine health record studies (RR 0.67, 95% CI 0.17 to 2.66). This was supported by the pooled results from both cohort (RR 0.71, 95% CI 0.39 to 1.28) and routine health record studies (RR 0.82, 95% CI 0.39 to 1.71) when comparisons were made to the offspring of women with untreated epilepsy. For topiramate, the prevalence of MCM was 3.9% (95% CI 2.3 to 6.5) from cohort study data and 4.1% (0.0 to 27,050.1) from routine health record studies. Risk ratios were significantly higher for children exposed to topiramate in comparison to the children of women without epilepsy in cohort studies (RR 4.07, 95% CI 1.64 to 10.14) but not in a smaller comparison to the children of women with untreated epilepsy (RR 1.37, 95% CI 0.57 to 3.27); few data are currently available from routine health record studies. Exposure in utero to topiramate was also associated with significantly higher RRs in comparison to other ASMs for oro-facial clefts. Data for all other ASMs were extremely limited. Given the observational designs, all studies were at high risk of certain biases, but the biases observed across primary data collection studies and secondary use of routine health records were different and were, in part, complementary. Biases were balanced across the ASMs investigated, and it is unlikely that the differential results observed across the ASMs are solely explained by these biases.

AUTHORS' CONCLUSIONS

Exposure in the womb to certain ASMs was associated with an increased risk of certain MCMs which, for many, is dose-dependent.

Advances in Epidemiological Methods and Utilisation of Large Databases: A Methodological Review of Observational Studies on Central Nervous System Drug Use in Pregnancy and Central Nervous System Outcomes in Children

INTRODUCTION

Studies have used various epidemiological approaches to study associations between central nervous system (CNS) drug use in pregnancy and CNS outcomes in children. Studies have generally focused on clinical adverse effects, whereas variations in methodologies have not received sufficient attention.

OBJECTIVE

Our objective was to review the methodological characteristics of existing studies to identify any limitations and recommend further research.

METHODS

A systematic literature search was conducted on observational studies listed in PubMed from 1 January 1946 to 21 September 2017. Following independent screening and data extraction, we conducted a review addressing the trends of relevant studies, differences between various data sources, and methods used to address bias and confounders; we also conducted statistical analyses.

RESULTS

In total, 111 observational studies, 25 case-control studies, and 86 cohort studies were included in the review. Publications dating from 1978 to 2006 mainly focused on antiepileptic drugs, but research on antidepressants increased from 2007 onwards. Only one study focused on antipsychotic use during pregnancy. A total of 46 studies obtained data from an administrative database/registry, 20 from ad hoc disease registries, and 41 from ad hoc clinical samples. Most studies (58%) adjusted the confounding factors using general adjustment, whereas only a few studies used advanced methods such as sibling-matched models and propensity score methods; 42 articles used univariate analyses and 69 conducted multivariable regression analyses.

CONCLUSION

Multiple factors, including different study designs and data sources, have led to inconsistent findings in associations between CNS drug use in pregnancy and CNS outcomes in children. Researchers should allow for study designs with clearly defined exposure periods, at the very least in trimesters, and use advanced confounding adjustment methodology to increase the accuracy of the findings.

Combining adverse pregnancy and perinatal outcomes for women exposed to antiepileptic drugs during pregnancy, using a latent trait model

Background

Application of latent variable models in medical research are becoming increasingly popular. A latent trait model is developed to combine rare birth defect outcomes in an index of infant morbidity.

Methods

This study employed four statewide, retrospective 10-year data sources (1999 to 2009). The study cohort consisted of all female Florida Medicaid enrollees who delivered a live singleton infant during study period. Drug exposure was defined as any exposure to Antiepileptic drugs (AEDs) during pregnancy. Mothers with no AED exposure served as the AED unexposed group for comparison. Four adverse outcomes, birth defect (BD), abnormal condition of new born (ACNB), low birth weight (LBW), and pregnancy and obstetrical complication (PCOC), were examined and combined using a latent trait model to generate an overall severity index. Unidimentionality, local independence, internal homogeneity, and construct validity were evaluated for the combined outcome.

Results

The study cohort consisted of 3183 mother-infant pairs in total AED group, 226 in the valproate only subgroup, and 43,956 in the AED unexposed group. Compared to AED unexposed group, the rate of BD was higher in both the total AED group (12.8% vs. 10.5%, P < .0001), and the valproate only subgroup (19.6% vs. 10.5%, P < .0001). The combined outcome was significantly correlated with the length of hospital stay during delivery in both the total AED group (Rho = 0.24, P < .0001) and the valproate only subgroup (Rho = 0.16, P = .01). The mean score for the combined outcome in the total AED group was significantly higher (2.04 ± 0.02 vs. 1.88 ± 0.01, P < .0001) than AED unexposed group, whereas the valproate only subgroup was not.

Conclusions

Latent trait modeling can be an effective tool for combining adverse pregnancy and perinatal outcomes to assess prenatal exposure to AED, but evaluation of the selected components is essential to ensure the validity of the combined outcome.

Electronic supplementary material

The online version of this article (doi:10.1186/s12884-016-1190-7) contains supplementary material, which is available to authorized users.

Monotherapy treatment of epilepsy in pregnancy: congenital malformation outcomes in the child

BACKGROUND

There is evidence that certain antiepileptic drugs (AEDs) are teratogenic and are associated with an increased risk of congenital malformation. The majority of women with epilepsy continue taking AEDs throughout pregnancy; therefore it is important that comprehensive information on the potential risks associated with AED treatment is available.

OBJECTIVES

To assess the effects of prenatal exposure to AEDs on the prevalence of congenital malformations in the child.

SEARCH METHODS

We searched the Cochrane Epilepsy Group Specialized Register (September 2015), Cochrane Central Register of Controlled Trials (CENTRAL) (2015, Issue 11), MEDLINE (via Ovid) (1946 to September 2015), EMBASE (1974 to September 2015), Pharmline (1978 to September 2015), Reprotox (1983 to September 2015) and conference abstracts (2010-2015) without language restriction.

SELECTION CRITERIA

We included prospective cohort controlled studies, cohort studies set within pregnancy registries and randomised controlled trials. Participants were women with epilepsy taking AEDs; the two control groups were women without epilepsy and women with epilepsy who were not taking AEDs during pregnancy.

DATA COLLECTION AND ANALYSIS

Three authors independently selected studies for inclusion. Five authors completed data extraction and risk of bias assessments. The primary outcome was the presence of a major congenital malformation. Secondary outcomes included specific types of major congenital malformations. Where meta-analysis was not possible, we reviewed included studies narratively.

MAIN RESULTS

We included 50 studies, with 31 contributing to meta-analysis. Study quality varied, and given the observational design, all were at high risk of certain biases. However, biases were balanced across the AEDs investigated and we believe that the results are not explained by these biases.Children exposed to carbamazepine (CBZ) were at a higher risk of malformation than children born to women without epilepsy (N = 1367 vs 2146, risk ratio (RR) 2.01, 95% confidence interval (CI) 1.20 to 3.36) and women with untreated epilepsy (N = 3058 vs 1287, RR 1.50, 95% CI 1.03 to 2.19). Children exposed to phenobarbital (PB) were at a higher risk of malformation than children born to women without epilepsy (N = 345 vs 1591, RR 2.84, 95% CI 1.57 to 5.13). Children exposed to phenytoin (PHT) were at an increased risk of malformation compared with children born to women without epilepsy (N = 477 vs 987, RR 2.38, 95% CI 1.12 to 5.03) and to women with untreated epilepsy (N = 640 vs 1256, RR 2.40, 95% CI 1.42 to 4.08). Children exposed to topiramate (TPM) were at an increased risk of malformation compared with children born to women without epilepsy (N = 359 vs 442, RR 3.69, 95% CI 1.36 to 10.07). The children exposed to valproate (VPA) were at a higher risk of malformation compared with children born to women without epilepsy (N = 467 vs 1936, RR 5.69, 95% CI 3.33 to 9.73) and to women with untreated epilepsy (N = 1923 vs 1259, RR 3.13, 95% CI 2.16 to 4.54). There was no increased risk for major malformation for lamotrigine (LTG). Gabapentin (GBP), levetiracetam (LEV), oxcarbazepine (OXC), primidone (PRM) or zonisamide (ZNS) were not associated with an increased risk, however, there were substantially fewer data for these medications.For AED comparisons, children exposed to VPA had the greatest risk of malformation (10.93%, 95% CI 8.91 to 13.13). Children exposed to VPA were at an increased risk of malformation compared with children exposed to CBZ (N = 2529 vs 4549, RR 2.44, 95% CI 2.00 to 2.94), GBP (N = 1814 vs 190, RR 6.21, 95% CI 1.91 to 20.23), LEV (N = 1814 vs 817, RR 5.82, 95% CI 3.13 to 10.81), LTG (N = 2021 vs 4164, RR 3.56, 95% CI 2.77 to 4.58), TPM (N = 1814 vs 473, RR 2.35, 95% CI 1.40 to 3.95), OXC (N = 676 vs 238, RR 3.71, 95% CI 1.65 to 8.33), PB (N = 1137 vs 626, RR 1.59, 95% CI 1.11 to 2.29, PHT (N = 2319 vs 1137, RR 2.00, 95% CI 1.48 to 2.71) or ZNS (N = 323 vs 90, RR 17.13, 95% CI 1.06 to 277.48). Children exposed to CBZ were at a higher risk of malformation than those exposed to LEV (N = 3051 vs 817, RR 1.84, 95% CI 1.03 to 3.29) and children exposed to LTG (N = 3385 vs 4164, RR 1.34, 95% CI 1.01 to 1.76). Children exposed to PB were at a higher risk of malformation compared with children exposed to GBP (N = 204 vs 159, RR 8.33, 95% CI 1.04 to 50.00), LEV (N = 204 vs 513, RR 2.33, 95% CI 1.04 to 5.00) or LTG (N = 282 vs 1959, RR 3.13, 95% CI 1.64 to 5.88). Children exposed to PHT had a higher risk of malformation than children exposed to LTG (N = 624 vs 4082, RR 1.89, 95% CI 1.19 to 2.94) or to LEV (N = 566 vs 817, RR 2.04, 95% CI 1.09 to 3.85); however, the comparison to LEV was not significant in the random-effects model. Children exposed to TPM were at a higher risk of malformation than children exposed to LEV (N = 473 vs 817, RR 2.00, 95% CI 1.03 to 3.85) or LTG (N = 473 vs 3975, RR 1.79, 95% CI 1.06 to 2.94). There were no other significant differences, or comparisons were limited to a single study.We found significantly higher rates of specific malformations associating PB exposure with cardiac malformations and VPA exposure with neural tube, cardiac, oro-facial/craniofacial, and skeletal and limb malformations in comparison to other AEDs. Dose of exposure mediated the risk of malformation following VPA exposure; a potential dose-response association for the other AEDs remained less clear.

AUTHORS' CONCLUSIONS

Exposure in the womb to certain AEDs carried an increased risk of malformation in the foetus and may be associated with specific patterns of malformation. Based on current evidence, LEV and LTG exposure carried the lowest risk of overall malformation; however, data pertaining to specific malformations are lacking. Physicians should discuss both the risks and treatment efficacy with the patient prior to commencing treatment.

The treatment of epilepsy in pregnancy: The neurodevelopmental risks associated with exposure to antiepileptic drugs

A number of antiepileptic drugs (AEDs) have been confirmed as teratogens due to their association with an increased malformation rate. The majority of research to date does not find an association between prenatal exposure to monotherapy carbamazepine, lamotrigine or phenytoin and neurodevelopmental outcome in comparison to control children and noted higher abilities in comparison to children exposed to valproate; but further work is needed before conclusions can be drawn. Data for levetiracetam was limited to one study, as was the evidence for topiramate. Sodium valproate exposure appeared to carry a dose dependent risk to the developing brain, with evidence of reduced levels of IQ, poorer verbal abilities and increased rate of autistic spectrum disorder both in comparison to control children and children exposed to other AEDs. The severity of the neurodevelopmental deficits associated with prenatal exposure to valproate highlight the critical need to consider neurodevelopmental outcomes as a central aspect of teratological research.

Valproic acid after five decades of use in epilepsy: time to reconsider the indications of a time-honoured drug

Since the serendipitous discovery of its anticonvulsant properties more than 50 years ago, valproic acid has become established as an effective broad-spectrum antiepileptic drug that is particularly useful for the management of generalised epilepsies, for which treatment alternatives are few. However, during the past few years increasing evidence has accumulated that intake of valproic acid during pregnancy is associated with a significant risk of dose-dependent teratogenic effects and impaired postnatal cognitive development in children. Because of these risks, valproic acid should not be used as a first-line drug in women of childbearing potential whenever equally or more effective alternative drugs are available-as in the case of focal epilepsy. In some generalised epilepsy syndromes, such as juvenile myoclonic epilepsy, valproic acid has better documented efficacy than alternative drugs and drug selection should be a shared decision between the clinician and the informed patient based on careful risk-benefit assessment.

Antiepileptic drug use by pregnant women enrolled in Florida Medicaid

OBJECTIVE

The study aims were to investigate secular trends in antiepileptic drug (AED) use in women during pregnancy, and to compare the use of first- and second-generation AEDs.

METHODS

Study participants consisted of female Florida Medicaid beneficiaries, older than 15 years, and pregnant within the time period 1999 to 2009. Fifteen AEDs were categorized into first and second generation of AEDs. Continuous use of AEDs was defined as at least 2 consecutive AED prescriptions totaling more than a 30-day supply. Polytherapy was defined as 2 or more AEDs continuously used for at least 30 overlapping days. Annual prevalence was estimated and compared.

RESULTS

We included 2,099 pregnant women who were enrolled in Florida Medicaid from 1999 to 2009 and exposed to AEDs during pregnancy. Although there were fluctuations, overall AED use in the study cohort did not increase from 2000 to 2009 (β ± standard error [SE]: -0.07 ± 0.06, p = 0.31). The use of first-generation AEDs decreased (β ± SE: -6.21 ± 0.47, p < 0.0001), whereas the use of second-generation AEDs increased (β ± SE: 6.27 ± 0.52, p < 0.0001) from 2000 to 2009. AED use in polytherapy did not change through the study period. Valproate use reduced from 23% to 8% in the study population (β ± SE: -1.61 ± 0.36, p = 0.0019), but this decrease was only for women receiving an AED for epilepsy and was not present for other indications.

CONCLUSION

The second-generation AEDs are replacing first-generation AEDs in both monotherapy and polytherapy. Valproate use has declined for epilepsy but not other indications. Additional changes in AED use are expected in future years.

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.

Topiramate for the treatment of epilepsy and other nervous system disorders

Initially synthesized as an oral hypoglycemic agent, topiramate was approved for use as an anticonvulsant in 1996. Its broad spectrum efficacy in epilepsy, including as monotherapy and in children, is well established. Topiramate has also been used in the management of nonepileptic neurologic and psychiatric conditions, including migraine prophylaxis (with firmly established efficacy), obesity (with some evidence of long-term maintenance of weight loss), substance dependence, bipolar disorder and neuropathic pain, and it has been investigated as a possible neuroprotective agent. Paresthesias and cognitive side effects are the most common troublesome adverse effects. Recent trends towards lower doses may help achieve the best combination of efficacy and tolerability.

Pharmacology and pharmacogenomics of neurological medications used in pregnancy

Pregnancy increases the pharmacological management challenge of numerous neurological diseases as a result of complex physiological changes. Understanding pregnancy-induced changes in pharmacokinetic and pharmacodynamic parameters can lead to better outcomes for both the mother and baby. Although the application of pharmacogenomics in maternal-fetal medicine is in its infancy, further research and developments will provide important new developments for managing the efficacy of drug treatments during pregnancy and improving maternal-fetal safety. Although a wide variety of neurological medications are used during pregnancy, this article will focus on the drugs with currently known pharmacogenomic implications.

Epileptogenesis in the developing brain

The neonatal brain has poorly developed GABAergic circuits, and in many of them GABA is excitatory, favoring ictogenicity. Frequently repeated experimental seizures impair brain development in an age-dependent manner. At critical ages, they delay developmental milestones, permanently lower seizure thresholds, and can cause very specific cognitive and learning deficits, such as the permanent impairment of neuronal spatial maps. Some types of experimental status epilepticus cause neuronal necrosis and apoptosis, and are followed by chronic epilepsy with spontaneous recurrent seizures, others appear relatively benign, so that seizure-induced neuronal injury and epileptogenesis are highly age-, seizure model-, and species-dependent. Experimental febrile seizures can be epileptogenic, and hyperthermia aggravates both neuronal injury and epileptogenicity. Antiepileptic drugs, the mainstay of treatment, have major risks of their own, and can, at therapeutic or near-therapeutic doses, trigger neuronal apoptosis, which is also age-, drug-, cell type-, and species-dependent. The relevance of these experimental results to human disease is still uncertain, but while their brains are quite different, the basic biology of neurons in rodents and humans is strikingly similar. Further research is needed to elucidate the molecular mechanisms of epileptogenesis and of seizure- or drug-induced neuronal injury, in order to prevent their long-term consequences.

Fetal hydantoin syndrome and its anaesthetic implications: a case report

Fetal hydantoin syndrome is a rare disorder that is believed to be caused by exposure of a fetus to the anticonvulsant drug phenytoin. The classic features of fetal hydantoin syndrome include craniofacial anomalies, prenatal and postnatal growth deficiencies, underdeveloped nails of the fingers and toes, and mental retardation. Less frequently observed anomalies include cleft lip and palate, microcephaly, ocular defects, cardiovascular anomalies, hypospadias, umbilical and inguinal hernias, and significant developmental delays. Anaesthesia for incidental surgery in such a patient poses unique challenges for the anesthesiologist. We report the successful management of a 4-year-old male child with fetal hydantoin syndrome, cleft palate, spina bifida, atrial septal defect, and dextrocardia for tibialis anterior lengthening under subarachnoid block.

Pregnancy outcome after in utero exposure to valproate : evidence of dose relationship in teratogenic effect

BACKGROUND

Valproate is a first-line antiepileptic agent and is also used in the treatment of bipolar disorder and migraine. It is a known human teratogen. The objective of the study was to evaluate the teratogenic risk of valproate.

METHODS

All callers who contacted the Israeli Teratology Information Service (TIS) between 1994 and 2004 for information about gestational exposure to valproate were enrolled in the study. After the expected date of delivery, these women were followed up by telephone interview about their pregnancy outcome using a structured questionnaire. Data obtained from women who contacted the TIS about valproate exposure during pregnancy were then compared with data obtained from callers who were counselled for nonteratogenic exposures over the same timeframe. The main outcome measure was the rate of major congenital anomalies.

RESULTS

The outcomes of 154 valproate-exposed pregnancies (96.1% at least in the first trimester) were compared with those of 1315 pregnancies of women in the TIS database who were counselled for nonteratogenic exposures. The rate of major anomalies (some multiple) in the valproate group exposed in the first trimester was higher compared with controls after exclusion of genetic or cytogenetic anomalies (8 of 120 [6.7%] vs 31 of 1236 [2.5%], p = 0.018, relative risk [RR] = 2.66, 95% CI 1.25, 5.65). There were no cases of neural tube defect in the valproate-exposed group. Five of the eight major anomalies in the valproate group were cardiovascular, two of eight were mentally retarded, two of five male infants with major anomalies had hypospadias and three of eight were suspected of having fetal valproate syndrome. A daily dose > or =1000 mg was associated with the highest teratogenic risk (7 of 32 [21.9%] vs 31 of 1236 [2.5%], RR = 8.72, 95% CI 4.16, 18.30). In the subgroup exposed to polytherapy there was a 4-fold increase in the rate of major anomalies compared with controls. All major anomalies were in the group treated for epilepsy.

CONCLUSION

When valproate treatment cannot be avoided in the first trimester of pregnancy, the lowest effective dose should be prescribed, preferably as monotherapy, to minimize its teratogenic risk.

Pregnancy outcomes in women with epilepsy: a systematic review and meta-analysis of published pregnancy registries and cohorts

PURPOSE

To conduct a systematic review and meta-analysis to quantify the incidence of congenital malformations (CMs) and other pregnancy outcomes as a function of in utero anti-epileptic drug (AED) exposure.

METHODS

We performed a systematic literature review to identify all published registries and cohort studies of births from pregnant women with epilepsy (WWE) that reported incidence of CMs. Overall incidences were calculated using a random effects model.

RESULTS

The review included 59 studies that met inclusion/exclusion criteria, involving 65,533 pregnancies in WWE and 1,817,024 in healthy women. The calculated incidence of births with CM in WWE [7.08%; 95% CIs 5.62, 8.54] was higher than healthy women [2.28%; CIs 1.46, 3.10]. Incidence was highest for AED polytherapy [16.78%; CIs 0.51, 33.05]. The AED with the highest CM incidence was valproate, which was 10.73% [CIs 8.16, 13.29] for valproate monotherapy.

CONCLUSIONS

Results of this systematic literature review suggest that the overall incidence of CMs in children born of WWE is approximately threefold that of healthy women. The risk is elevated for all AED monotherapy and further elevated for AED polytherapy compared to women without epilepsy. The risk was significantly higher for children exposed to valproate monotherapy and to polytherapy of 2 or more drugs when the polytherapy combination included phenobarital, phenytoin, or valproate. Further research is needed to delineate the specific risk for each individual AED and to determine underlying mechanisms including genetic risk factors.

Neurodevelopmental delay in children exposed to antiepileptic drugs in utero: a critical review directed at structural study-bias

INTRODUCTION

The general issue whether in utero exposure to antiepileptic drugs (AEDs) causes congenital malformations (teratogenicity) was raised as early as 1968. The 'congenital hydantoin syndrome' after intrauterine exposure to phenytoin (PHT) was first described in 1975. In 1984, DiLiberti proposed the label 'Fetal Valproate Syndrome' (FVS) for children with a cluster of minor congenital anomalies in the form of dysmorphic facial appearances with or without major abnormalities after intra-uterine exposure to valproate (VPA). Later, also the presence of central nervous system (CNS) dysfunction became part of the description. The question whether developmental delay, educational impairment, or behavioural disorders are also a characteristic of intrauterine exposure to AEDs and especially VPA, is of major importance to many women with epilepsy, parents and physicians involved.

METHODS

Literature was searched using MEDLINE and other relevant databases: 56 studies were identified and interpreted.

RESULTS

The identified studies do not allow definite conclusions. The possibility of neurodevelopmental delay, behavioural disorders, or learning disabilities as an outcome of in utero exposure to AEDs and especially VPA, needs to be considered seriously. The literature however does not provide evidence for a valid risk estimate. Moreover the evidence found for a specific increased risk for VPA could be structurally biased.

DISCUSSION

The major problem in this field is the methodology and in particular the existence of important confounding factors that complicate any attempt to correlate intra-uterine exposure to AEDs with neurodevelopmental delay. We propose a number of guidelines for studies on behavioural teratogenicity.

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.

Teratogenicity of antiepileptic drugs: role of drug metabolism and pharmacogenomics

The approach to clinical decision-making pertaining to the use of antiepileptic drugs (AEDs) during pregnancy has relied on previous accumulated experience and, since the 1990s, on data from pregnancy registries. The limitations of this process are that no information regarding the chemical attributes of the AED under consideration, nor the role of a number of enzyme systems that are known to interact with foreign compounds to modify their potential for harm, are included. The role of the hepatic mixed function oxidase system may be especially important in conferring teratogenic risk. However, systems such as epoxide hydrolase, glutathione reductase, superoxide dismutase and other toxin-scavenging systems may be important modifiers that lower the risk. Knowledge is also accumulating on the interactions of AEDs with molecular targets such as histone deacetylase and peroxisome proliferator-activated receptors that may play important roles in teratogenesis. While our knowledge of these factors are incomplete, progress can be achieved by beginning to include these concepts in our discussion on the topic and by promoting research that may improve our ability to individualize the analysis of risk for a specific patient with regards to specific AEDs.

Drug treatment during pregnancy and isolated orofacial clefts in hungary

OBJECTIVE

To evaluate the possible association between all kinds of drug treatments during pregnancy and isolated cleft lip with or without cleft palate (CL/P) and posterior cleft palate (PCP) in the offspring.

SETTING

The dataset of the large population-based Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1996, was evaluated.

PARTICIPANTS

One thousand three hundred seventy-four cases with isolated CL/P and 601 with PCP, plus 38,151 population controls (without birth defects) and 20,868 malformed controls with other defects.

INTERVENTION

In this observation case-control study the data collection was based on prospective medical records particularly prenatal logbook, retrospective maternal data via a self-reported questionnaire, and home visits of nonresponding mothers.

MAIN OUTCOME MEASURES

Isolated CL/P and PCP associated with drug treatments during pregnancy.

RESULTS

An increased risk for isolated CL/P was found in cases born to mothers treated with amoxicillin, phenytoin, oxprenolol, and thiethylperazine during the second and third month of pregnancy, i.e., the critical period of isolated CL/P. Risk of isolated PCP was increased in mothers with oxytetracycline and carbamazepine treatment during the third and fourth month of pregnancy, i.e., the critical period of PCP.

CONCLUSIONS

This study confirmed the orofacial cleft (OFC) inducing effect of phenytoin, carbamazepine, oxytetracycline, and thiethylperazine and suggested a possible association between OFCs and oxprenolol and amoxicillin. However, drugs may have only a limited role in the origin of isolated OFCs.

Neuroteratogens in man: An overview with special emphasis on the teratogenicity of antiepileptic drugs in pregnancy

The most active growth and development of the human cerebrum and cerebellum occurs in the second half of pregnancy and in the first year of life. It is therefore not surprising that many teratogens may also affect development causing slight, moderate or even severe brain damage. The "classical" antiepileptic drugs (AEDs) valproic acid (VPA), phenytoin, phenobarbital, primidone and carbamazepine are all considered to be teratogenic. They may increase the rate of major congenital anomalies including neural tube defects (NTD), cause specific facial and other dysmorphic features--the "Anti Epileptic Drug Syndrome" (AEDS) and often some degree of mental impairment. Of these AEDs, the most teratogenic seems to be valproic acid, causing about 2% of NTD and an additional increase of 4-8% in major congenital anomalies. Phenytoin also increases the rate of various anomalies, but apparently not of NTD. Phenobarbital primidone and carbamazepine are also teratogenic and impair intellectual function but to a lesser extent than VPA and phenytoin. Cognition is mainly impaired in the children that also exhibit the AEDS. The impairment is slight to moderate, leaving the affected children with a close to borderline intelligence. Lamotrigine monotherapy in pregnancy seems to be relatively safe. In general, polytherapy is more dangerous to the fetus than monotherapy and, at least for VPA and lamotrigine, there seems to be a "threshold effect".

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.

Using current evidence in selecting antiepileptic drugs for use during pregnancy

Children born to mothers taking antiepileptic drugs (AEDs) are at increased risk for findings of fetal anticonvulsant syndrome. Accepted treatment paradigms to minimize fetal risks include use of AED monotherapy and folic acid supplementation. However, as data are acquired from several ongoing pregnancy registries, differential risks among the various AED monotherapy regimens are being defined, further improving fetal outcomes.

Pregnancy in women who have epilepsy

Ideal, comprehensive care of women who have epilepsy during the reproductive years must include effective preconceptional counseling and preparation. The importance of planned pregnancies with effective birth control should be emphasized, with consideration of the effects of the enzyme-inducing AEDs on lowering efficacy of hormonal contraceptive medications and the need for back-up barrier methods. Before pregnancy occurs, the patient's diagnosis and treatment regimen should be reassessed. Once the diagnosis of epilepsy is confirmed, it is important to verify if the individual patient continues to need medications and if she is taking the most appropriate AED to balance control of her seizures with teratogenic risks. For most women who have epilepsy, withdrawal of all AEDs before pregnancy is not a realistic option. A decision to undergo a trial while not taking AEDs before a planned pregnancy should be based on the same principles used for AED withdrawal in any person who has epilepsy. The taper should be completed at least 6 months before planned conception to provide some reassurance that seizures are not going to recur. If a woman who has epilepsy is in the more prevalent category of needing AEDs for seizure control, then monotherapy at the lowest effective dosage should be used. If large daily doses are needed, then frequent smaller doses or extended-release formulations may be helpful to avoid high peak levels. Some of the newest information about differential risks between AEDs also should be considered. The woman's AED regimen should be optimized and folate supplementation should begin before pregnancy. Given that 50% of pregnancies are unplanned in the United States, folate supplementation should be encouraged in all women of childbearing age who are taking any AED for any indication. Dosing recommendations vary from 0.4 mg/d to 5 mg/d. It is not uncommon for a physician to consider changing AED regimens when the patient first reports that she is pregnant. In many cases, she already is in or past the critical period of organogenesis (Table 3). If a woman who has epilepsy presents after conception and is taking a single AED that is effective, her medication usually should not be changed. Exposing the fetus to a second agent during a crossover period of AEDs only increases the teratogenic risk, and seizures are more likely to occur with any abrupt medication changes. If a woman is on polytherapy, it may be possible to switch to monotherapy safely. Seizure control remains an important goal during pregnancy. In particular, convulsive seizures place the mother and fetus at risk. Nonconvulsive seizures also may be harmful, especially if they involve falling or other forms of trauma. Monitoring serum AED levels during pregnancy can be helpful in optimizing seizure control. Prenatal screening can detect major malformations in the first and second trimesters. Vitamin K1 is given 10 mg/d orally during the last month of pregnancy followed by 1 mg intramuscularly or intravenously to the new-born. Although women who have epilepsy and women who are taking AEDs for other indications do have increased risks for maternal and fetal complications, these risks can be reduced considerably with effective preconceptional planning and careful management during pregnancy and the postpartum period.

Statistics on Deliveries of Mothers with Epilepsy at Yokohama City University Hospital

PURPOSE

To survey and summarize the treatment of pregnant women with epilepsy and to obtain data for the improvement of daily treatment regimens.

METHODS

We reviewed medical records of 36 deliveries of 25 mothers with epilepsy at Yokohama City University Hospital from September 1991 to December 2000 and statistically compared the differences in drug-taking profiles, complications during pregnancy, types of delivery, and complications at delivery between the epilepsy group and a control group (656 total deliveries after 22 weeks except for epilepsy cases in 1991 and 1992 at Yokohama City University Hospital).

RESULTS

Of the 25 mothers with epilepsy, three with idiopathic generalized epilepsy, 12 were symptomatic for partial epilepsy. Their mean age at delivery was 29.0 years. The mean age at onset of epilepsy was 13.9 years. Of the 36 pregnancies, 30 (83.3%) cases continued antiepileptic drug (AED) taking throughout the pregnancies; 23 (63.9%) cases received monotherapy. Phenobarbital was the most frequently used drug in monotherapies. Seven (19.4%) cases received polytherapy. Seven (19.4%) patients experienced epileptic seizures during pregnancy. One case showed a low serum AED level. No statistically significant difference was found in complications during pregnancy, types of delivery, or complications at delivery, excluding abnormal rotation in the birth canal. Congenital malformation (cleft lip with palate) was observed in one (2.9%) case. The mother was 39 years old at delivery and had myoma uteri. Onset of epilepsy was at 14 years. She had been taking three kinds of AEDs: 1,400 mg/day of sodium valproate (VPA), 1.5 mg/day of clonazepam (CZP), and 200 mg/day of zonisamide (ZNS). Serum concentrations at pregnancy week 10 were 85.3 microg/ml VPA, 18.1 microg/L CZP, and 10.5 microg/ml ZNS. She also had been taking folic acid, 5 mg/day, but the serum concentration was not measured.

CONCLUSIONS

The method of treatment and the management of pregnancy were left to the discretion of each doctor. However, in most cases, monotherapy was selected; and the frequency of complications was not significantly different from that of the control group, excluding the frequency of abnormal rotation in the birth canal. However, we could have been more proactive in calculating the risks of pregnancy for women with epilepsy and adjusted treatment in anticipation of a planned pregnancy, before the patient actually became pregnant. Additionally, a closer working relationship between the obstetrician and the physician who treats the epilepsy would seem to be a further requirement for the patient's well-being, as well as her child's, during pregnancy.

Effects of Seizures and Their Treatment on Fetal Brain

PURPOSE

To describe the effects of pregnancy on seizures, the effects of seizures during pregnancy on the fetus, and the effects of antiepileptic drugs (AEDs) on fetal brain and development.

METHODS

The available literature was reviewed and summarized.

RESULTS

There is a paucity of prospective studies. Retrospective studies indicate that, during pregnancy, alterations in seizure frequency can occur in an unpredictable fashion. Generalized tonic-clonic seizures may have adverse effects on the fetus. It is unclear whether complex partial seizures or absence seizures have negative consequences. AEDs may have potentially detrimental effects on the fetus and its subsequent development, but the full spectrum and clinical significance are under investigation. Monotherapy is strongly encouraged.

CONCLUSIONS

Dealing with the pregnant epileptic patient is a difficult and challenging task. Although there are several risks for the mother and the fetus, most epileptic women bear normal, healthy children.

The specialist nurse role in the treatment of refractory epilepsy

The main aim of epilepsy treatment is rapid and complete control of seizures without antiepileptic drug (AED) side effects. This outcome is achieved in 60-70% of newly diagnosed patients. In refractory epilepsy, new AEDs render some additional patients seizure free but make treatment more complex. The choice of AEDs, their differing pharmacokinetics, efficacy, tolerability and potential interactions are multiplied. Up to of 75% of patients develop AED side effects, most AEDs can cause paradoxical reactions, and when AED doses are changed seizures may worsen. Despite the increased complexity of epilepsy treatment and the biomedical and psychosocial consequences of uncontrolled seizures, many patients have difficulty accessing specialist services. A service that involves the epilepsy nurse specialist (ENS) giving patients and General Practitioners (GPs) free access to treatment advice has recently been established to improve care. Over a 2-week period 60 treatment-related telephone or outpatient consultations were provided out of a total of 124 contacts. Changes to the AED regimen were implemented in 44/60, and the GP was notified by letter in 31/44. The audit results are presented and epilepsy treatment including AED efficacy, tolerability, interactions and side effects are discussed.

Seizure disorders in pregnancy

This article discusses seizure disorders in pregnancy. Seizure disorder affects 1.1 million women of reproductive age in the United States. In 1995, the annual cost of treatment of patients who had epilepsy was estimated to be 12.5 billion dollars. Seizures are disorganized firing of neural cells. Epilepsy is the presence of two or more seizures in the absence of an identifiable cause for the seizures (ie, no intracranial or metabolic abnormality). Epilepsy has an impact on many aspects of women's health, particularly with respect to reproduction. The management of women who have epilepsy during pregnancy is the focus of this article.

Common antiepileptic drugs in pregnancy in women with epilepsy

BACKGROUND

The potential adverse effects of antiepileptic drug (AED) exposure in pregnancy have been well recognised but the relative risks of specific antiepileptic drug exposures remain poorly understood.

OBJECTIVES

To assess the adverse effects of commonly used antiepileptic drugs on maternal and fetal outcomes in pregnancy in women with epilepsy. Comparison of outcomes following specific antiepileptic drug exposures in utero to unexposed pregnancies in the general population or women with epilepsy are described. The current manuscript reports the first phase of this review which focuses upon neurodevelopmental outcomes in children exposed to antiepileptic drugs in utero.

SEARCH STRATEGY

We searched MEDLINE, Pharmline, EMBASE, Reprotox and TERIS from 1966 to December 2003. Review articles and conference abstracts were also hand searched.

SELECTION CRITERIA

All randomized controlled trials, prospective cohorts of children of pregnant women with and without epilepsy and case control studies (cases: developmental delay or impaired cognitive outcome, control: normal development) were included.

DATA COLLECTION AND ANALYSIS

Methodological quality was assessed using an adapted version of the Newcastle-Ottawa Scale. The wide variety of outcome measures and methodological approaches made meta-analysis difficult and a descriptive analysis of the results is presented.

MAIN RESULTS

PART A 1b - DEVELOPMENTAL OUTCOMES: The majority of studies were of limited quality. There was little evidence about which specific drugs carry more risk than others to the development of children exposed in utero. The results between studies are conflicting and while most failed to find a significant detrimental outcome with in utero exposure to monotherapy with carbamazepine, phenytoin or phenobarbitone, this should be interpreted cautiously. There were very few studies of exposure to sodium valproate. Polytherapy exposure in utero was more commonly associated with poorer outcomes, as was exposure to any AEDs when analysis did not take into account type of AED. The latter may reflect the large proportion of children included in these studies who were in fact exposed to polytherapy.

REVIEWERS' CONCLUSIONS

PART A 1b - DEVELOPMENTAL OUTCOMES: Based on the best current available evidence it would seem advisable for women to continue medication during pregnancy using monotherapy at the lowest dose required to achieve seizure control. Polytherapy would seem best avoided where possible. More population based studies adequately powered to examine the effects of in utero exposure to specific monotherapies which are used in everyday practice are required.

Malformation Rates in Children of Women with Untreated Epilepsy

BACKGROUND

It is widely quoted that women with epilepsy have a higher than baseline risk for giving birth to a child with malformations, independent of the effects of antiepileptic drugs.

OBJECTIVE

To determine, based on available evidence, if epilepsy per se represents a teratogenic risk. To systematically review all studies investigating the occurrence of major malformation rates among children of treated or untreated women with epilepsy and non-exposed controls who do not have epilepsy.

METHODS

A meta-analysis, using a random effects model, was conducted of all cohort and case-control studies reporting malformation rates in children of women with epilepsy exposed or unexposed to antiepileptic drugs compared with that of children of nonepileptic women. Medline (1966-2001), EMBASE, the Cochrane database as well as REPROTOX (an information system on environmental hazards to human reproduction and development) databases were accessed.

RESULTS

We found ten studies reporting results of untreated epilepsy (n = 400) and their non-epileptic healthy controls (n = 2492). Nine out of ten studies also reported results on 1443 patients exposed to antiepileptic drugs and their 2526 unexposed healthy controls. The risk for congenital malformations in the offspring of women with untreated epilepsy was not higher than among nonepileptic controls (odds ratio [OR] = 1.92; 95% CI 0.92-4.00). There was evidence of publication bias, thus with bias removed the OR was 0.99 (95% CI 0.49-2.01). In contrast, the offspring of epileptic women who received antiepileptic drugs had higher incidences of malformation than controls (OR 3.26; 95% CI 2.15-4.93).

CONCLUSION

Our study does not support the commonly held view that epilepsy per se represents a teratogenic risk. Our study suggests that this view is the result of a publication bias, with several small (< 100 participants) positive studies leading to a premature conclusion.

Medical and Social Issues Related to Posttraumatic Seizures in Persons With Traumatic Brain Injury

BACKGROUND

The incidence of late posttraumatic seizures (LPTS) in individuals with traumatic brain injury (TBI) ranges anywhere from 5% to 18.9% in civilian populations up to 32% to 50% in military personnel.

OBJECTIVE

This article reviews the current knowledge about the incidence and prevalence of LPTS following a TBI, the risk factors for developing LPTS, and the options available for preventing the development of LPTS.

METHODS

The psychosocial ramifications of LPTS following a TBI have not been well explored. As a result, the psychosocial findings from the current literature on epilepsy will be reviewed with the hope that the need for future TBI outcomes research to investigate the impact of LPTS following a TBI or, at least, to include LPTS as a potential contributing factor will be recognized.

Reproductive and metabolic disorders in women with epilepsy

Epilepsy is a common neurologic disorder affecting women during the reproductive years. Seizures and some antiepileptic drugs (AEDs) can compromise reproductive health, and some AEDs can adversely affect carbohydrate and bone metabolism. Women with epilepsy have lower birth rates and more frequent anovulatory menstrual cycles. This appears to be related to seizure- and AED-associated reproductive endocrine disturbances. Carbamazepine (CBZ), phenytoin (PHT), and phenobarbital (PB) induce hepatic cytochrome P450 enzymes and lower endogenous estrogens, adrenal and ovarian androgens, and contraceptive steroids. Valproate (VPA) inhibits steroid hormone metabolism, elevates androgens, and predisposes to phenotypic signs of hyperandrogenism-hirsutism, obesity, acne, and frequent anovulatory cycles. VPA is associated with weight gain, probably by altering insulin metabolism. CBZ, PHT, and VPA, but not lamotrigine (LTG), are associated with lower levels of calcium. PHT, but not VPA or LTG, appears to accelerate bone turnover. AED effects on bone mineral metabolism may explain the elevated risk of fracture described in women with epilepsy. Prospective pregnancy registries are beginning to provide information about AED-associated teratogenesis. The North American Antiepileptic Drug Pregnancy Registry reports a 12% rate of major malformations after first trimester exposure to PB and an 8.6% rate after first trimester exposure to VPA. A prospective LTG-specific registry reports a 1.8% chance of major malformations after the first trimester. The registries will continue to release information as data become significant. In the meantime, practitioners can be alert to signs and symptoms of reproductive or metabolic health disturbances and participate in pregnancy registry efforts.

Epilepsy and women's health: family planning, bone health, menopause, and menstrual-related seizures

Epilepsy uniquely affects more than 1 million American women and girls. Health care providers must be aware of the specific concerns and issues regarding the different effects epilepsy has on male and female patients. Epilepsy and antiepileptic drugs substantially affect women's health in the areas of menstruation, contraception, sexual function, pregnancy, menopause, and bone health. Optimal care of women with epilepsy requires collaboration among neurologists, obstetrician-gynecologists, internists, family practitioners, genetic counselors, and nurse educators. This article reviews some areas of concern for women living with epilepsy.

Amelioration of sodium valproate-induced neural tube defects in mouse fetuses by maternal folic acid supplementation during gestation

Infants of epileptic women treated with valproic acid (VPA) during pregnancy have a higher risk of developing spina bifida than those of the general population. VPA induces exencephaly in experimental animal embryos. But the pathogenetic mechanism remains rather elusive. Antiepileptic drugs (AED) in general accentuate pregnancy-imposed fall in maternal folate levels. Periconceptional folic acid supplementation is reported to protect embryos from developing neural tube defects (NTD). Conflicting results have been reported by experimental studies that attempted to alleviate VPA-induced NTD by folic acid. Our objectives were to determine the critical developmental stages and an effective dose of folic acid for the prevention of VPA-induced exencephaly in mouse fetuses. A single teratogenic dose of 400 mg/kg of VPA was administered to TO mice on gestation day (GD) 7 or 8. It was followed by (1) a single dose of 12 mg/kg of FA (folinic acid) or (2) 3 doses of FA 4 mg/kg each. In experiment (3), FA (4 mg/kg) was administered thrice daily starting on GD 5 and continued through GD 10. These animals received VPA on GD 7 or 8. VPA and B12 concentrations were determined by radioimmunoassay. The single heavy dose of FA had no rescue effect on NTD. Three divided doses of FA on GD 7 and continuous dosing of FA from GD 5 through GD 10 substantially reduced the VPA-induced exencephaly in the fetuses. In the later experiments, the neural folds elevated faster than the non-supplemented group. VPA considerably reduced maternal plasma folate and B12 concentrations. The heavy dose of FA only moderately improved vitamin levels. Three divided doses of FA elevated the vitamin levels slightly better but it was the prolonged dosing of FA that was associated with sustained elevation of plasma levels higher than the control levels and acceleration of neural tube closure thus accounting for the pronounced protection against VPA-induced NTD development. These data suggest that plasma levels of FA and B12 have to be kept substantially elevated and maintained high throughout organogenesis period to protect embryos against VPA-induced NTD in this mouse model.

The importance of drug interactions in epilepsy therapy

Long-term antiepileptic drug (AED) therapy is the reality for the majority of patients diagnosed with epilepsy. One AED will usually be sufficient to control seizures effectively, but a significant proportion of patients will need to receive a multiple AED regimen. Furthermore, polytherapy may be necessary for the treatment of concomitant disease. The fact that over-the-counter drugs and nutritional supplements are increasingly being self-administered by patients also must be considered. Therefore the probability of patients with epilepsy experiencing drug interactions is high, particularly with the traditional AEDs, which are highly prone to drug interactions. Physicians prescribing AEDs to patients with epilepsy must, therefore, be aware of the potential for drug interactions and the effects (pharmacokinetic and pharmacodynamic) that can occur both during combination therapy and on drug discontinuation. Although pharmacokinetic interactions are numerous and well described, pharmacodynamic interactions are few and usually concluded by default. Perhaps the most clinically significant pharmacodynamic interaction is that of lamotrigine (LTG) and valproic acid (VPA); these drugs exhibit synergistic efficacy when coadministered in patients with refractory partial and generalised seizures. Hepatic metabolism is often the target for pharmacokinetic drug interactions, and enzyme-inducing drugs such as phenytoin (PHT), phenobarbitone (PB), and carbamazepine (CBZ) will readily enhance the metabolism of other AEDs [e.g., LTG, topiramate (TPM), and tiagabine (TGB)]. The enzyme-inducing AEDs also enhance the metabolism of many other drugs (e.g., oral contraceptives, antidepressants, and warfarin) so that therapeutic efficacy of coadministered drugs is lost unless the dosage is increased. VPA inhibits the metabolism of PB and LTG, resulting in an elevation in the plasma concentrations of the inhibited drugs and consequently an increased risk of toxicity. The inhibition of the metabolism of CBZ by VPA results in an elevation of the metabolite CBZ-epoxide, which also increases the risk of toxicity. Other examples include the inhibition of PHT and CBZ metabolism by cimetidine and CBZ metabolism by erythromycin. In recent years, a more rational approach has been taken with regard to metabolic drug interactions because of our enhanced understanding of the cytochrome P450 system that is responsible for the metabolism of many drugs, including AEDs. The review briefly discusses the mechanisms of drug interactions and then proceeds to highlight some of the more clinically relevant drug interactions between AEDs and between AEDs and non-AEDs. Understanding the fundamental principles that contribute to a drug interaction may help the physician to better anticipate a drug interaction and allow a graded and planned therapeutic response and, therefore, help to enhance the management of patients with epilepsy who may require treatment with polytherapy regimens.

Folic Acid and Epilepsy

Folic acid has been a topic of discussion within the epilepsy community for several decades. Folic acid was initially suspected to be epileptogenic ( 1 ), but that concern has been resolved, as research has demonstrated that folic acid in less than supraphysiologic concentrations does not promote seizures. Epileptologists are now concerned that folic acid may be too low in persons with epilepsy taking some antiepileptic drugs (AEDs). Low serum and red blood cell levels of folic acid in women of childbearing potential increase the risk of fetal birth defects. For men and women, low levels of folic acid are associated with elevated homocysteine and an increased risk for cardiovascular disease. A convincing argument now develops that routine folic acid supplementation is important for women and men receiving AEDs.

Altered pharmacokinetics and metabolism of valproate after replacement of conventional valproate with the slow-release formulation in epileptic patients

Altered metabolism of valproate has been suggested as the mechanism of teratogenicity and hepatotoxicity of valproate. This study aimed at examining whether pharmacokinetics of a slow-release formulation of valproate affects valproate metabolism. Thirty-one epileptic patients were treated with fixed-doses of conventional valproate for at least 2 months. Thereafter, the drug was replaced with the same doses of slow-release formulation of valproate for 2 months. Blood samplings for determination of valproate and its metabolites by gas chromatography-mass spectrometry were performed at three time-points (just before morning dose and at 1 and 5 hr after morning dose) during both treatment phases. There was a significant difference (P < 0.005) in the mean serum concentration (+/- S.D.) of valproate after 1 hr between conventional valproate (63.1 +/- 27.9 microg/ml) and slow-release formulation of valproate (45.7 +/- 19.5 microg/ml). Mean serum concentrations (+/- S.D.) of 4-en and hydroxy metabolites after 5 hr were significantly reduced after replacement with slow-release formulation of valproate (4-en: 29.5 +/- 14.0-->23.0 +/- 15.3 ng/ml, 3-OH: 488.5 +/- 234.0-->419.6 +/- 171.1 ng/ml, 4-OH: 404.3 +/- 124.7-->342.8 +/- 147.6 ng/ml, 5-OH: 102.8 +/- 54.4-->81.0 +/- 43.6 ng/ml). The present study suggests that smaller diurnal fluctuations in valproate concentrations during treatment with slow-release formulation of valproate result in decreased formations of minor metabolites including 4-en, the most toxic metabolite.

Folic Acid and Epilepsy

Folic acid has been a topic of discussion within the epilepsy community for several decades. Folic acid was initially suspected to be epileptogenic (1), but that concern has been resolved, as research has demonstrated that folic acid in less than supraphysiologic concentrations does not promote seizures. Epileptologists are now concerned that folic acid may be too low in persons with epilepsy taking some antiepileptic drugs (AEDs). Low serum and red blood cell levels of folic acid in women of childbearing potential increase the risk of fetal birth defects. For men and women, low levels of folic acid are associated with elevated homocysteine and an increased risk for cardiovascular disease. A convincing argument now develops that routine folic acid supplementation is important for women and men receiving AEDs.

The teratogenic effect of carbamazepine: a meta-analysis of 1255 exposures

Maternal use of antiepileptic drugs during pregnancy has been associated with an increased risk of major congenital abnormalities in the fetus. Carbamazepine (CBZ) is an antiepileptic drug that was developed and marketed mainly for the treatment of epileptic seizures. Some investigators described an increased rate of major congenital anomalies following treatment with CBZ during pregnancy while others found no such increase. In order to quantify better the risks of exposure to CBZ during pregnancy, we pooled data from prospective studies known to us. We found in prospective studies involving 1255 cases of exposure that CBZ therapy increased the rate of congenital anomalies, mainly neural tube defects, cardiovascular and urinary tract anomalies, and cleft palate. CBZ may also induce a pattern of minor congenital anomalies and developmental retardation, but our study did not address these endpoints. CBZ also appears to reduce gestational age at delivery. A combination of CBZ with other antiepileptic drugs is more teratogenic than CBZ monotherapy. Children born to untreated epileptic women do not appear to have an increased rate of major birth defects. In light of these results, we recommend performing a level 2 ultrasound and fetal echocardiography in women treated with CBZ during pregnancy.