Anticonvulsant drugs and malformations is there a drug specificity?

Specific Birth Defects Following Antiseizure Medications Used By Pregnant Women With Epilepsy

Background and Objectives

Previous research has been limited in the comprehensive study of associations between the use of individual antiseizure medications (ASMs) in pregnancy and specific groups of birth defects, and systematic reviews and meta-analyses on the topic are limited by pooled samples and study designs. This study investigated birth defects related to ASM use in pregnancy in children born to women with epilepsy in Sweden over 20 years.

Methods

We used data from Swedish national registers to follow a cohort of 17,996 children born to women diagnosed with epilepsy any time before conception in Sweden from 1996 to 2016, following them through 2017. We examined maternal-reported use of the 4 most commonly reported ASMs: lamotrigine (n = 2,148, 11.9%), carbamazepine (n = 1,940, 10.8%), valproic acid (n = 1,043, 5.80%), and levetiracetam (n = 587, 3.26%). We identified birth defects using diagnoses recorded at the time of discharge from the hospital and inpatient and outpatient diagnoses recorded in the first year of life. Models were estimated in a stepped fashion: unadjusted, adjusted for covariates, among a subcohort born to women diagnosed 10 years before conception (n = 14,586), and restricted to monotherapy.

Results

Valproic acid use in pregnancy had the strongest and most widespread associations with birth defects in children, with carbamazepine also having links to several birth defects, including respiratory system and genital organ defects. Lamotrigine use in pregnancy was associated with cleft lip/palate and chromosomal abnormalities. Levetiracetam was most often used with other ASMs and preliminarily associated with many birth defects.

Discussion

Our findings support avoidance of valproic acid use in pregnancy whenever possible. Lamotrigine and carbamazepine may be safer alternatives. However, these medications were also associated with certain birth defects, including some not reported previously. We are among the first to examine the possible effects of levetiracetam use in pregnancy, though more research is needed to investigate this further.

Antiseizure medication in early nervous system development. Ion channels and synaptic proteins as principal targets

The main strategy for the treatment of epilepsy is the use of pharmacological agents known as antiseizure medication (ASM). These drugs control the seizure onset and improves the life expectancy and quality of life of patients. Several ASMs are contraindicated during pregnancy, due to a potential teratogen risk. For this reason, the pharmacological treatments of the pregnant Women with Epilepsy (WWE) need comprehensive analyses to reduce fetal risk during the first trimester of pregnancy. The mechanisms by which ASM are teratogens are still under study and scientists in the field, propose different hypotheses. One of them, which will be addressed in this review, corresponds to the potential alteration of ASM on ion channels and proteins involved in relevant signaling and cellular responses (i.e., migration, differentiation) during embryonic development. The actual information related to the action of ASM and its possible targets it is poorly understood. In this review, we will focus on describing the eventual presence of some ion channels and synaptic proteins of the neurotransmitter signaling pathways present during early neural development, which could potentially interacting as targets of ASM. This information leads to elucidate whether these drugs would have the ability to affect critical signaling during periods of neural development that in turn could explain the fetal malformations observed by the use of ASM during pregnancy.

Prevalence and factors associated with polypharmacy: a systematic review and Meta-analysis

Introduction

Polypharmacy is commonly associated with adverse health outcomes. There are currently no meta-analyses of the prevalence of polypharmacy or factors associated with polypharmacy. We aimed to estimate the pooled prevalence of polypharmacy and factors associated with polypharmacy in a systematic review and meta-analysis.

Methods

MEDLINE, EMBASE, and Cochrane databases were searched for studies with no restrictions on date. We included observational studies that reported on the prevalence of polypharmacy among individuals over age 19. Two reviewers extracted study characteristics including polypharmacy definitions, study design, setting, geography, and participant demographics. The risk of bias was assessed using the Newcastle-Ottawa Scales. The main outcome was the prevalence of polypharmacy and factors associated with polypharmacy prevalence. The pooled prevalence estimates of polypharmacy with 95% confidence intervals were determined using random effects meta-analysis. Subgroup analyses were undertaken to evaluate factors associated with polypharmacy such as polypharmacy definitions, study setting, study design and geography. Meta-regression was conducted to assess the associations between polypharmacy prevalence and study year.

Results

106 full-text articles were identified. The pooled estimated prevalence of polypharmacy in the 54 studies reporting on polypharmacy in all medication classes was 37% (95% CI: 31-43%). Differences in polypharmacy prevalence were reported for studies using different numerical thresholds, study setting, and publication year. Sex, study geography, study design and geographical location were not associated with differences in polypharmacy prevalence.

Discussion

Our review highlights that polypharmacy is common particularly among older adults and those in inpatient settings. Clinicians should be aware of populations who have an increased likelihood of experiencing polypharmacy and efforts should be made to review the appropriateness of prescribed medications and occurrence of adverse effects potentially associated with polypharmacy.

Conclusions and implications

Clinicians should be aware of the common occurrence of polypharmacy and undertake efforts to minimize inappropriate polypharmacy whenever possible.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-022-03279-x.

Pregnancy outcome following opioid exposure: A cohort study

INTRODUCTION

Opioids constitute a cornerstone of pain relief treatment. However, opioid safety during pregnancy has not been well established. Recent studies reported an association between in utero opioid exposure and spina bifida.

METHODS

In order to further evaluate the association of opioids exposure during pregnancy with adverse pregnancy outcomes, we conducted a large historical cohort by linking four databases: medications dispensations, births, pregnancy terminations for medical reasons and infant hospitalizations during the years of 1999-2009. Confounders that were controlled for included maternal age, ethnicity, maternal diabetes, smoking status, parity, obesity, year and folic acid intake. A secondary analysis for total major malformations and for spina bifida was performed using propensity score matching for first trimester exposure.

RESULTS

Of the 101,586 women included in the study, 3003 were dispensed opioids during the first trimester. Intrauterine exposure to opioids was not associated with overall major malformations (adjusted odds ratio (aOR) 0.97, 95% CI 0.83-1.13), cardiovascular malformations (aOR = 0.89, 95% CI 0.70-1.13) other malformations by systems or spina bifida in particular. However, the risk for spina bifida among newborns and abortuses who were exposed to codeine was four times higher than that of the unexposed (aOR = 4.42, 95% CI 1.60-12.23). This association remained significant in a secondary analysis using propensity score matching. Third trimester exposure to opioids was not associated with low birth weight (aOR = 1.08, 95% CI 0.77-1.52), perinatal death (aOR = 1.38, 95% CI 0.64-2.99) and other adverse pregnancy outcomes.

CONCLUSIONS

These findings suggest that opioids exposure (as a homogenous group) is not a significant risk factor for overall major malformations. Exposure to codeine during the first trimester was found to be associated with increased risk of spina bifida. However, this finding was based on a small number of cases and need to be verified in future work.

Drug-related teratogenic and pathologic causes of birth defects in a tertiary hospital in Southwestern Nigeria

Birth defects are important causes of neonatal morbidity and mortality. A good understanding of the etiology is a vital step toward developing improved treatment and preventive strategies. We conducted an audit of medical records of newborns with birth abnormalities in a tertiary hospital over a 10-year period, using a Pro forma designed to collect information on obstetric history, antenatal history, sociodemographics of parents, and the type of birth abnormality. Of the 180 medical records reviewed, female babies were 92 (51.1%) and male babies were 86 (47.8%). The mean age of the fathers was 38.2 + 6.2, and mothers 31.8 + 4.9. Majority 115 (63.9%) of the mothers had records of acute illnesses, and 23 (12.8%) chronic illnesses during pregnancy. Unspecified febrile illness 44 (38.3%), malaria 40 (34.8%), typhoid 8 (6.9%), hypertension 13 (56.5%), pregestational diabetes 4 (17.4%), and HIV 3 (13.0%) were the commonest maternal pathologies. Most of the documented birth abnormalities were Down's syndrome 34 (15.2%); congenital hydrocephalus 32 (14.3%); acyanotic congenital heart defect 30 (13.4%); deformity of the digits 26 (11.6%); and ventricular septal defect 20 (8.9%). The prevalence of maternal pathologies calls for concern, as these may be implicated in birth defects, therefore should be further investigated in future studies.

Maternal Drug Use and Infant Cleft Lip/Palate with Special Reference to Corticoids

Objective

To study the association between maternal drug use in early pregnancy and orofacial cleft in the infant.

Design

Register analysis based on prospectively collected information.

Patients

All delivered women in Sweden July 1, 1995, through December 31, 2001.

Main outcome measure

Presence of orofacial cleft in infant.

Results

Prospective information on maternal drug use during the first trimester, as reported in early pregnancy, was studied in 1142 infants with orofacial clefts, isolated or with other malformations, excluding chromosome anomalies. Any drug use was not associated with clefts (odds ratio [OR] = 0.98, 95% confidence interval [95% CI] = 0.85 to 1.13), with isolated clefts (OR = 0.92) with isolated median cleft palate (OR = 1.03, 95% CI = 0.79 to 1.36) or with isolated cleft lip with or without cleft palate (OR = 0.86, 95% CI = 0.71 to 1.05). Reported use of multivitamins, folic acid, or B12 was not associated with a decrease in orofacial cleft risk (OR = 1.00, 95% CI = 0.63 to 1.52). ORs above 2 were seen for some drugs: sulfasalazine, naproxen, and anticonvulsants, but only a few exposed cases occurred. An association between glucocorticoid use and infant cleft was indicated and seemed to be strongest for median cleft palate.

Conclusion

Maternal drug use seems to play only a small role for the origin of orofacial clefts, at least in Sweden.

Epilepsy during pregnancy: focus on management strategies

In the US, more than one million women with epilepsy are of childbearing age and have over 20,000 babies each year. Patients with epilepsy who become pregnant are at risk of complications, including changes in seizure frequency, maternal morbidity and mortality, and congenital anomalies due to antiepileptic drug exposure. Appropriate management of epilepsy during pregnancy may involve frequent monitoring of antiepileptic drug serum concentrations, potential preconception switching of antiepileptic medications, making dose adjustments, minimizing peak drug concentration with more frequent dosing, and avoiding potentially teratogenic medications. Ideally, preconception planning will be done to minimize risks to both the mother and fetus during pregnancy. It is important to recognize benefits and risks of current and emerging therapies, especially with revised pregnancy labeling in prescription drug product information. This review will outline risks for epilepsy during pregnancy, review various recommendations from leading organizations, and provide an evidence-based approach for managing patients with epilepsy before, during, and after pregnancy.

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.

Advantages and problems with pregnancy registries: observations and surprises throughout the life of the International Lamotrigine Pregnancy Registry

PURPOSE

The International Lamotrigine Pregnancy Registry monitored for a signal of a substantial increase in the frequency of major congenital malformations associated with lamotrigine exposures in pregnancy over an 18-year period. Key methodological lessons are discussed.

METHODS

The strengths and weaknesses of the Registry were assessed using quantifiable methodological and operational parameters including enrollment, completeness of exposure and outcome data reporting, and lost to follow-up. The choice of comparator groups and stopping rules for registry closure were critically evaluated.

RESULTS

The reliance on voluntary reporting was associated with a clustered geographical distribution of registered pregnancies. The enrollment rate increased over time with new approvals and indications for lamotrigine and publication of interim data. Reporter burden was minimized through a streamlined data collection approach resulting in a high level of completeness of exposure and primary outcome data. Lost to follow-up rates were high (28.5% overall) representing a major limitation; incentives to increase the completeness of reporting failed to reduce rates. A lack of an internal comparator group complicated data interpretation; but external comparisons with multiple external groups allowed an assessment of consistency of outcome data across multiple data sources. A lack of a priori closure criteria prolonged the life of the Registry, and consideration of regulatory guidelines on this subject is encouraged at the time of conception of future registries.

CONCLUSIONS

A successful pregnancy exposure registry requires ongoing flexibility and continuous re-assessment of enrollment, recruitment, and retention methods and the availability of comparison data, throughout its lifecycle.

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.

Methodological approaches to evaluate teratogenic risk using birth defect registries: advantages and disadvantages

Background

Different approaches have been used in case-control studies to estimate maternal exposure to medications and the risk of birth defects. However, the performance of these approaches and how they affect the odds ratio (OR) estimates have not been evaluated using birth-defect surveillance programmes. The aim of this study was to evaluate the scope and limitations of three case-control approaches to assess the teratogenic risk of birth defects in mothers exposed to antiepileptic medications, insulin, or acetaminophen.

Methodology/Principal Findings

We studied 110,814 non-malformed newborns and 58,514 live newborns with birth defects registered by the Latin American Collaborative Study of Congenital Anomalies (ECLAMC) between 1967 and 2008. Four controls were randomly selected for each case in the same hospital and period, and three different control groups were used: non-malformed newborns (HEALTHY), malformed newborns (SICK), and a subgroup of SICK, only-exposed cases (OECA). Associations were evaluated using OR and Pearson's chi-square (P<0.01). There were no concordance correlations between the HEALTHY and OECA designs, and the average OR differences ranged from 3.0 to 11.5 for the three evaluated medicines. The overestimations observed for HEALTHY design were increased as higher OR values were given, with a high and statistically significant correlation between the difference and the mean. On the contrary, the concordance correlations obtained between the SICK and OECA designs were quite good, with no significant differences in the average risks.

Conclusions

The HEALTHY design estimates the true population OR, but shows a high rate of false-positive results presumably caused by differential misclassification bias. This bias decreases with the increase of the proportion of exposed controls. SICK and OECA odds ratios cannot be considered a direct estimate of the true population OR except under certain conditions. However, the SICK and OECA designs could provide practical information to generate hypotheses about potential teratogens.

Prevention, diagnosis and services

This chapter summarizes how prevention, diagnosis and services can result from the activities of a research programme on the group of rare diseases constituted by congenital anomalies. The Spanish Collaborative Study of Congenital Malformations (ECEMC) is a research programme based on a case-control registry of consecutive newborn infants with congenital anomalies. Its aim is the prevention of this group of rare diseases, through the research on their causes and pathogenesis, combined with the translational activity to transfer the benefits of this knowledge to the general population and health care providers. Its experience could be applied to the research on other rare diseases. The different levels of prevention (primary, secondary, tertiary and quaternary) are briefly defined, and the way in which these levels are being applied or can be applied to congenital defects prevention is reviewed. The main primary prevention measures regarding congenital anomalies are also detailed. To this respect, the benefits derived from the activity of Teratology Information Services (TIS), for the general population as well as for health care providers, are explained. It is finally emphasized how the epidemiological data can contribute to the prevention of that group of rare diseases.

Increasing trends of tobacco use in medical students in Slovakia--a reason for concern?

OBJECTIVE

The article analyses changes in tobacco use in medical students in Slovakia in 1995, 1999 and 2004.

METHODS

Questionnaire survey in 448 students of the Jessenius Faculty of Medicine, Comenius University in Martin, Slovakia, was carried out in October and November 2004. Data were compared with similar surveys carried out in 1995 and 1999.

RESULTS

Prevalence of daily smoking in men increased from 11.1 in 1995 to 21.8% in 2004. In women, within 1995-2004, daily smoking increased from 5.2% to 12.3%, occasional smoking from 11.6% to 19.8%. Also proportion of women initiating smoking during their university study increased. In both genders the proportion of never smokers dramatically dropped between 1995 and 1999 (in men from 43.2% to 23.2%; in women from 61.9 to 18.2).

CONCLUSION

Upward trend in tobacco use, particularly in women, is a reason for concern. In medical faculties, principles of prevention should be more emphasized and the students motivated for healthy life-style and to fulfill their future role in public health. The situation noted among medical students indicates that a community in Slovakia is still not satisfactory inclined towards non-smoking and a dramatic decrease of tobacco use can hardly be expected either in the near future.

Folic acid sensitive birth defects in association with intrauterine exposure to folic acid antagonists

Since the protective effect of folic acid (FA) on birth defects is well known, it is reasonable to assume intrauterine exposure to FA antagonists increases the risk on these defects. We have therefore performed case-control analyses to investigate the risk of intrauterine exposure to FA antagonists, using data on births from the EUROCAT Northern Netherlands registry from 1997 to 2002. Of the 815 cases, 11 were exposed to a FA antagonist compared to 16 of the 1402 controls. For FA sensitive defects as a group, the study showed no effect after exposure to a FA antagonist (odds ratio (OR)=1.18, 95% CI: 0.55-2.57). We found no effect after exposure to a dihydrofolate reductase inhibitor (DHFRI) (OR 0.44, 95% CI: 0.12-1.54), but we did find a statistically significant effect after exposure to an antiepileptic drug (OR=3.45, 95% CI: 1.04-11.48). This study supports the findings of various other studies on the teratogenicity of antiepileptics. An association between DHFRIs and FA sensitive defects was not found.

Findings on potential teratogens from a case-control study in Western Australia

OBJECTIVES

To examine, in Western Australian women, pregnancy use of drugs that have been found to be associated with birth defect risks in other studies.

DESIGN

Data were used from a retrospective study of birth defects in which mothers were sent questionnaires asking about a variety of pregnancy events and exposures, including specific questions on medication use.

POPULATION

Case subjects were fetuses or infants with structural birth defects born in Western Australia from 1997 to 2000, identified from the Western Australian Birth Defects Registry. Control subjects were infants without birth defects, randomly selected from the Western Australian Midwives' Notification System.

MEASURES

First trimester uses of corticosteroids, medications that antagonise folic acid metabolism, and vasoactive drugs were compared between case and control mothers.

RESULTS

The mothers of 2.5, 2.4, and 1.9% of controls, cases, and oral cleft cases, respectively, reported corticosteroid use. The mothers of 0.6% of controls and 1.4% of cases used a folic acid antagonising medication, yielding an odds ratio of 2.3 (95% confidence interval, 0.58-9.4). The mothers of 4.5% of controls and 7.1% of cases used a vasoactive drug (pseudoephedrine, aspirin, ibuprofen, amphetamine, cocaine, or ecstasy). Cigarette smoking is also vasoactive. For exposure to both a vasoactive drug and cigarette smoking, the birth defect risk was 3.0 (0.92-9.6).

CONCLUSIONS

There was no difference in corticosteroid use between case and control mothers, although the number of exposed subjects was small. Odds ratio estimates for folic acid antagonists and vasoactive agents support previously reported associations, but they were not statistically significant.

Drug-induced congenital defects: strategies to reduce the incidence

Approximately 1% of congenital anomalies relate to pharmacological exposure and are. in theory, preventable. Prevention consists of controlled administration of drugs known to have teratogenic properties (e.g. retinoids, thalidomide). When possible, prevention could take the form of the use of alternative pharmacological therapies during the pre-conception period for certain specific pathologies, selecting the most appropriate agent for use during pregnancy [e.g. haloperidol or a tricyclic antidepressant instead of lithium; anticonvulsant drug monotherapy in place of multitherapy; propylthiouracil instead of thiamazole (methimazole)], and substitution with the most suitable therapy during pregnancy (e.g. insulin in place of oral antidiabetics; heparin in place of oral anticoagulants; alpha-methyldopa instead of ACE inhibitors). Another strategy is the administration of drugs during pregnancy taking into account the pharmacological effects in relation to the gestation period (e.g. avoidance of chemotherapy during the first trimester, avoidance of nonsteroidal anti-inflammatory drugs in the third trimester, and avoidance of high doses of benzodiazepines in the period imminent to prepartum).

CPD-Education and self-assessment: Epilepsy and pregnancy

Pregnancies in women with epilepsy are high risk and need careful management by both the medical and obstetric teams due to the increased incidence of complications and adverse outcomes of pregnancy. By the time a pregnant woman with epilepsy presents, the foetus is virtually fully formed and the opportunity for altering drug treatment has passed. Women need to be counselled and told to seek advice about their anticonvulsant therapy should they wish to become pregnant. All major anticonvulsant drugs are teratogenic but the main risk to the developing foetus appears to be when the mother is on polytherapy especially if sodium valproate forms part of the combination. Folate supplements (5 mg) before conception are advisable. There appears to be a minor but significant increased risk of maternal complications in women with epilepsy such as hyperemesis gravidarum, pre-eclampsia and eclampsia, vaginal bleeding and premature labour. In the majority of women seizure control will not alter during pregnancy. Oral vitamin K should be given to the mother receiving enzyme-inducing antiepileptic drugs. Post-natal infant development: there is an increased risk of prematurity (9-11%), stillbirth, neonatal and perinatal death, haemorrhagic disease of the newborn, low Apgar scores and low birth weight (7-10%). Breast feeding: virtually all the anticonvulsant drugs are excreted in breast milk in low concentrations. Feeding difficulties, irritability and lethargy can occur. However, the benefits of breast feeding usually far outweigh any minor risks to the baby.

Folic acid antagonists during pregnancy and the risk of birth defects

BACKGROUND

Multivitamin supplementation in pregnant women may reduce the risks of cardiovascular defects, oral clefts, and urinary tract defects in their infants. We evaluated whether the folic acid component of multivitamins is responsible for the reduction in risk by examining the associations between maternal use of folic acid antagonists and these congenital malformations.

METHODS

We compared data on exposure to folic acid antagonists that act as dihydrofolate reductase inhibitors and to certain antiepileptic drugs for 3870 infants with cardiovascular defects, 1962 infants with oral clefts, and 1100 infants with urinary tract defects with data for 8387 control infants with malformations the risk of which is not reduced after vitamin supplementation. Mothers were interviewed within six months after delivery about their medication use.

RESULTS

The relative risks of cardiovascular defects and oral clefts in infants whose mothers were exposed to dihydrofolate reductase inhibitors during the second or third month after the last menstrual period, as compared with infants whose mothers had no such exposure, were 3.4 (95 percent confidence interval, 1.8 to 6.4) and 2.6 (95 percent confidence interval, 1.1 to 6.1), respectively. The relative risks of cardiovascular defects, oral clefts, and urinary tract defects after maternal exposure to antiepileptic drugs were 2.2 (95 percent confidence interval, 1.4 to 3.5), 2.5 (95 percent confidence interval, 1.5 to 4.2), and 2.5 (95 percent confidence interval, 1.2 to 5.0), respectively. Use of multivitamin supplements containing folic acid diminished the adverse effects of dihydrofolate reductase inhibitors, but not that of antiepileptic drugs.

CONCLUSIONS

Folic acid antagonists, which include such common drugs as trimethoprim, triamterene, carbamazepine, phenytoin, phenobarbital, and primidone, may increase the risk not only of neural-tube defects, but also of cardiovascular defects, oral clefts, and urinary tract defects. The folic acid component of multivitamins may reduce the risks of these defects.

Best practice guidelines for the management of women with epilepsy. The Women with Epilepsy Guidelines Development Group

Clinical guidelines for the treatment of epilepsy have been published. A statement on management issues for women with epilepsy has recently been produced by the American Academy of Neurology which has raised awareness of the issues facing women with epilepsy. The communication presented here aims to review current literature on specific issues relating to women with epilepsy, and proposes graded recommendations for its management within a UK health care framework.

Pharmacologically induced embryonic dysrhythmia and episodes of hypoxia followed by reoxygenation: a common teratogenic mechanism for antiepileptic drugs?

Antiepileptic drugs (AEDs), such as phenytoin (PHT), carbamazepine (CBZ), trimethadione (TMD), and phenobarbital (PB), have all been associated with a similar pattern of malformations, as well as growth retardation and developmental delay. Valproic acid (VPA) has been associated with a different pattern of malformations. Recent studies suggest that PHT's fetal adverse effect is related to its membrane stabilizing pharmacological properties (blockage of voltage-dependent ion channels). During a restricted sensitive period, this results in induction of concentration-dependent bradyarrhythmia in the embryo and episodes of hypoxia/reoxygenation. The aim of this study was to compare the potential of PHT, CBZ, PB, TMD, and dimethadione (DMD; the active metabolite of TMD) to cause bradyarrhythmias. All of these AEDs exert mainly their pharmacological effect via blockage of ion channels. VPA and vigabatrin (VGB), which are pharmacologically active mainly by other mechanisms, were also tested. C57 Bl/6J mouse embryos were cultured in vitro on gestation day 10 in vitro (in 20% rat serum). The drugs were suspended in either water or dimethylsulfoxide and administered into the culture medium in increasing concentrations up to 20 times the human therapeutic plasma concentration. A scoring system was employed in order to rank the drugs based on their potential to cause bradycardia, ventricular arrhythmia, and cardiac arrest in relation to human therapeutic concentrations. Based on this system, the drugs were ranked as follows: DMD = PHT >> PB = CBZ > TMD = VPA >> VGB (no potential). The results correlate well with the available clinical/experimental data of the tested AED's potential to induce hypoxia-related fetal adverse effects, such as oral clefts, distal limb defects, growth retardation, and developmental delay. The results support the idea that adverse fetal effects after in utero exposure to PHT, PB, CBZ, and TMD (via the active metabolite DMD) are initiated via a common pharmacological mechanism: blockage of ion channels in the developing heart in the early embryo resulting in bradyarrhythmias, hemodynamic alterations, and hypoxia/reoxygenation damage.

Maternal use of antiepileptic drugs and the risk of major congenital malformations: a joint European prospective study of human teratogenesis associated with maternal epilepsy

PURPOSE

To quantify the risks of intrauterine antiepileptic drug (AED) exposure in monotherapy and polytherapy.

METHODS

Data from five prospective European studies totaling 1,379 children were pooled and reanalyzed. Data were available for 1,221 children exposed to AED during pregnancy and for 158 children of unexposed control pregnancies.

RESULTS

Overall, when comparing a subgroup of 192 children exposed to AED with 158 children of matched nonepileptic controls, there was an increased risk of major congenital malformations (MCA) in children exposed to AED during gestation [relative risk (RR) 2.3; 95% confidence interval (CI): 1.2-4.7]. A significant increase in risk was found for children exposed to valproate (VPA) (RR 4.9; 95% CI: 1.6-15.0) or carbamazepine (CBZ) (RR 4.9; 95% CI: 1.3-18.0) in monotherapy. When comparing different AED regimens during all 1,221 pregnancies, risks of MCA were significantly increased for the combination of phenobarbital (PB) and ethosuximide (RR 9.8; 95% CI: 1.4-67.3) and the combination of phenytoin, PB, CBZ, and VPA (RR 11.0; 95% CI: 2.1-57.6). Offspring of mothers using > 1,000 mg VPA/day were at a significantly increased risk of MCA, especially neural tube defects, compared to offspring exposed < or =600 mg VPA/day (RR 6.8; 95% CI: 1.4-32.7). No difference in risk of MCA was found between the offspring exposed to 601-1,000 mg/day and < or =600 mg/day.

CONCLUSIONS

This reanalysis shows that VPA is consistently associated with an increased risk of MCA in babies born to mothers with epilepsy. Significant associations were also observed with CBZ. Larger prospective population-based studies are needed to evaluate the risks of many other less frequently prescribed treatment regimens, including newly marketed AEDs.

Adverse effects of established and new antiepileptic drugs: an attempted comparison

Seizures are but one aspect of the negative impact epilepsy has on patients' lives. Adverse effects of antiepileptic treatment may affect the patient's quality of life to an even greater extent than the occurrence of seizures. Adverse effects of antiepileptic drugs (AEDs) are common, and because the differences in efficacy are often marginal, adverse effects may be the most important factor in choosing the best AED for the patient. The search for more efficient and less toxic agents is constantly ongoing. Current evidence suggests that the new generation of AEDs is as efficient as the established AEDs and exhibits fewer adverse effects, but the scientific evidence from randomised clinical trials comparing established and new AEDs with each other is still pending.

Maternal carbamazepine and infant spina bifida

Women with epilepsy giving birth during 1973 to 1991 were identified by record linkage of Swedish health registries. Among 3,625 identified infants, 9 had spina bifida. A nested case-control study was performed, comparing drugs used in early pregnancy in the 9 cases and in 18 controls, matched for year of delivery, maternal age, and parity. Six of the spina bifida mothers had used carbamazepine and two had used valproic acid. Among the controls, 5 women used carbamazepine and one valproic acid. There is an apparent excess risk for spina bifida after use of either of these two drugs, but it is not statistically significant when the analysis is restricted to drug-using women. The findings support earlier reports in the literature of an association between carbamazepine and spina bifida.

Vertebral arch nonfusion and juvenile myoclonic epilepsy

Neural tube defects (NTD) are known to occur at a higher rate in pregnancies of women with epilepsy. Antiepileptic drugs (AEDs), notably valproate (VPA) and carbamazepine (CBZ), have been identified as risk factors, but a familial aggregation of this condition also occurs in the absence of pharmacologic teratogens. Spina bifida occulta, defined as a nonsymptomatic nonfusion of vertebral arches, has been suggested to be genetically determined, with an increased prevalence in patients with primary generalized epilepsy, and that the presence of this trait in fetal development can be enhanced pharmacologically to produce NTD such as meningomyelocele. In this study, plain abdominal radiographs were obtained from 56 patients with juvenile myoclonic epilepsy (JME) and 56 age- and sex-matched controls. The radiographs were presented in a random order to an unbiased radiologist. No difference in prevalence of vertebral arch nonfusion (VAN) was noted between the two groups. Even if it has no increased frequency in patients with epilepsy, however, VAN is a common radiologic finding, and its relation to symptomatic neural tube defects should be clarified in future studies.

The contribution of maternal epilepsy and its treatment to the etiology of oral clefts: a population based case-control study

The associations between maternal epilepsy and anticonvulsant drug therapy with the risk of oral clefts in the offspring were investigated using data from a population-based case-control study. Cases included 238 infants with cleft lip +/- cleft palate (CLP) and 107 infants with cleft palate (CP) ascertained through the Metropolitan Atlanta Congenital Defects Program (MACDP) between 1968 and 1980. Controls included 3029 population-based normal infants. Histories of maternal epilepsy and drug therapy during pregnancy were compared between cases and controls using maternal interviews and reviews of hospital medical records. Maternal epilepsy was associated with increased risk of nonsyndromic CLP (OR = 3.78, 95% C.I. 1.65-7.88), and less with CP (OR = 1.75, 95% C.I. 0.20-6.99). Therapy during pregnancy was associated with the greatest excess risk (CLP OR = 7.77, C.I. 2.02-26.0; CP OR = 3.61, C.I. 0.08-26.5). The use of polytherapy was associated with the highest risk (CLP OR = 10.5, C.I. 1.52-59.9). Adjustment for potential confounding variables in the study did not change these findings. In this well-defined population, maternal epilepsy and its treatment account for a small proportion of nonsyndromic oral clefts (attributable fraction CLP = 3.3%, CP = 0.9%).

The effect of administration time on malformations induced by three anticonvulsant agents in C57BL/6J mice with emphasis on forelimb ectrodactyly

Exposure of C57BL/6J mice to three anticonvulsant derivatives, namely, dimethadione, sodium valproate, and sodium diphenylhydantoin, each induced postaxial forelimb ectrodactyly. The agents were administered at gestational days 9, 9 1/3, 9 2/3, and 10. It was determined that administration at day 9 2/3 induced the highest percentage of forelimb ectrodactyly for each of the three agents. The forelimb ectrodactyly response in the C57BL/6J strain was compared with the A/J strain (Collins et al., Teratology, 41:61-70, 1990); it was found that the C57BL/6J strain was more sensitive to dimethadione and the A/J strain was more sensitive to diphenylhydantoin and sodium valproate. The position of vertebral defects induced by sodium valproate correlated with the time of drug administration. The overall syndrome of malformations induced by the three anticonvulsant agents was relatively similar in the two mouse strains and differed between each of the anticonvulsant agents.

Congenital malformations before and after the onset of maternal epilepsy

A total of 222 pregnancies in 56 mothers were studied, 48 pregnancies occurred in 17 mothers before the onset of epilepsy (Group 1). The same group went on to develop epilepsy, receive anticonvulsants and further conceive 43 pregnancies (Group 1a). In the other 39 mothers 131 pregnancies occurred after the onset of epilepsy and while receiving anticonvulsants (Group 2). The incidence of major congenital malformations among live births was significantly higher in Group 2 (14.4%) when compared with all pregnancies in Groups 1 and 1a (1.2%), P less than 0.025 and in Group 1 alone (2.2%) P less than 0.05. There was no significant difference between Groups 1 and Group 1a. Age at first pregnancy in Group 1 was 18.9 years +/- 3.7 SD, which was significantly younger than Group 2, 21.7 years +/- 5.1 SD, p less than 0.05. The age of onset of epilepsy was significantly younger in Group 2 than in Group 1, 15.1 years +/- 6 SD vs 23.3 years +/- 4.6 SD, p less than 0.001. The duration of epilepsy was significantly longer in Group 2 compared with Group 1, 13.8 years +/- 8.7 SD vs 6.1 years +/- 2.6 SD, p less than 0.001. Patients on polytherapy had a significantly higher risk of major malformations compared to those on monotherapy, 20.2% vs 1.3%, p less than 0.001. Our data suggest that epileptic mothers with the highest risk of having offspring with major malformations were those with a long duration of epilepsy combined with exposure to multiple anticonvulsant drugs.

Parental epilepsy, anticonvulsant drugs, and reproductive outcome: epidemiologic and experimental findings spanning three decades; 2: Human studies

Evidence accumulated over the past three decades has established AEDs as human teratogens. Important developments in the delineation of these compounds as human teratogens include: the demonstration of a consistent association between in utero exposure to AEDs and an increased occurrence of single major malformations, the description of AED-induced dysmorphogenic syndromes; demonstration of a dose-response relationship, both in terms of the number and dosage of AEDs; and evidence that pharmacogenetic differences in the metabolism of AEDs are strongly correlated with the occurrence of congenital malformations. Furthermore, the experimental animal findings, having accumulated in parallel to those of human studies, strongly support the teratogenic role of AEDs. Areas that require further amplification and clarification in future studies are the relative contribution of AEDs and other factors, such as genetic predisposition and maternal seizures, particularly with respect to the occurrence of minor anomalies, growth retardation, and developmental outcome; the relative teratogenicity of specific monotherapies and polytherapies; the predictive role of pharmacogenetic differences in the metabolism of AEDs in the occurrence of structural and functional abnormalities; and characterization of the precise nature of the pharmacogenetic defect underlying the aforementioned differences in AED metabolism. Attempts should also be made in future prospective studies to monitor metabolite levels of AEDs, particularly the oxidative metabolites, in order to further elucidate the relative contribution of individual differences in metabolism in the determination of adverse fetal outcome. Similarly, further efforts should be made to assess the clinical significance of decreased growth parameters in terms of mental and neurologic development, and to ascertain whether there is any risk for such abnormalities in children who do not display overt or persistent reductions in physical growth parameters. This is critically important in light of the animal studies that have shown functional abnormalities at doses that do not necessarily produce structural defects. Future investigations would be conducted through collaborative studies that would encompass sufficiently large numbers of women to provide adequate power to the statistical analyses of the data obtained. Care would have to be exercised to establish a uniform protocol for the collaborating centers. Regionally based investigations would be preferable to studies based at special centers, in order to assess the relative role of risk factors associated with abnormal pregnancy outcomes in the epileptic population at large.(ABSTRACT TRUNCATED AT 400 WORDS)

Clinical manifestation of prenatal exposure to valproic acid using case reports and epidemiologic information

The present study includes 28 patients prenatally exposed to valproic acid (VPA) monitored by the Spanish Collaborative Study of Congenital Malformations (ECEMC), from April 1976 to December 1988. Among the 28 cases, 15 (53.6%) were exposed only to VPA and 13 (46.4%) to VPA plus other anticonvulsant drugs. The clinical manifestations observed in those prenatally exposed only to VPA, are compared with the abnormalities observed in those with prenatal exposure to VPA plus other anticonvulsant drugs. To better define the spectrum of clinical manifestation of the prenatal exposure to VPA we used, besides our clinical observations and those from the literature, all available epidemiological data. We consider that a "valproate embryofetopathy (VPEF)" could exist, because different anomalies have been observed in children prenatally exposed to VPA in monotherapy. A facial phenotype of VPA exposure has been reported, and epidemiologic studies have shown an increased risk for congenital defects. However, from a review of published cases as well as those in the present study, it appears that the spectrum of VAE in monotherapy may not include oral clefts.