Teratogenicity of anticonvulsant drugs. II: A prospective study

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.

Danish Population Based Study of Familial Epilepsy and Childhood Cancer

Objective

Results from studies investigating the association between maternal or child epilepsy, use of anticonvulsants in pregnancy, and childhood cancer are inconsistent and at times contradictory.

Methods

Linking Danish national databases, we obtained epilepsy and childhood cancer diagnoses, and anticonvulsant use data. We estimated adjusted odds ratios of all or specific childhood cancers in relation to maternal or child epilepsy and anticonvulsant therapies using conditional logistic regression.

Results

Maternal epilepsy was positively associated with all childhood cancers in offspring, specifically, with acute lymphoblastic leukemia (Odds Ratio (OR) = 1.68, 95% Confidence Interval (CI) = 1.16, 2.43) and Wilms tumor (OR = 2.13, 95%CI = 0.97, 4.68). When considering maternal ever (lifetime) ingestion of anticonvulsants, a positive association was found with all cancers (OR = 1.15, 95%CI = 1.01, 1.31), and central nervous system tumors (OR = 1.32, 95%CI = 1.03, 1.69) as well as neuroblastoma (OR = 2.05, 95%CI = 1.29, 3.28) among offspring. Maternal anticonvulsant use before or during the index pregnancy was related to CNS tumors in offspring (OR = 1.78, 95%CI = 0.99, 3.21), however the confidence interval included the null.

Significance

Maternal use of certain anticonvulsant medications may be a risk factor for cancer in offspring. Medical providers may need to consider what type of treatments to prescribe to pregnant mothers with epilepsy.

A review of the evidence on the risk of congenital malformations and neurodevelopmental disorders in association with antiseizure medications during pregnancy

Introduction: The majority of women with epilepsy require treatment with antiseizure medications (ASM) throughout pregnancy. However, in utero exposure to several ASM has been associated with an increased risk of congenital malformations and/or neurodevelopmental disorders (CM/NDD) in the child, but observational evidence is methodologically heterogeneous.Areas covered: We critically evaluate current evidence on the risk of CM/NDD in children of women with epilepsy after in utero exposure to different ASM. We highlight characteristics of different data sources and discuss their benefits and drawbacks. This review includes evidence published before December 2020.Expert opinion: Given the lack of randomized controlled trials, evidence on in utero safety of ASM originates from methodologically heterogeneous post-marketing observational studies based on registries, prospective cohorts, and large electronic health databases. It has been clearly demonstrated that valproate is associated with a high risk of CM/NDD, whereas lamotrigine and levetiracetam are relatively safe. However, evidence is less explicit for other ASM. Reported risks vary depending on the size and origin of the underlying study population, the definition of exposure and outcomes, and other aspects of the study design. Increased collaboration between data sources to increase sample size is desirable.

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.

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.

Association of maternal chronic disease with risk of congenital heart disease in offspring

BACKGROUND

Information about known risk factors for congenital heart disease is scarce. In this population-based study, we aimed to investigate the relation between maternal chronic disease and congenital heart disease in offspring.

METHODS

The study cohort consisted of 1 387 650 live births from 2004 to 2010. We identified chronic disease in mothers and mild and severe forms of congenital heart disease in their offspring from Taiwan's National Health Insurance medical claims. We used multivariable logistic regression analysis to assess the associations of all cases and specific types of congenital heart disease with various maternal chronic diseases.

RESULTS

For mothers with the following chronic diseases, the overall prevalence of congenital heart disease in their children was significantly higher than for mothers without these diseases: diabetes mellitus type 1 (adjusted odds ratio [OR] 2.32, 95% confidence interval [CI] 1.66-3.25), diabetes mellitus type 2 (adjusted OR 2.85, 95% CI 2.60-3.12), hypertension (adjusted OR 1.87, 95% CI 1.69-2.07), congenital heart defects (adjusted OR 3.05, 95% CI 2.45-3.80), anemia (adjusted OR 1.31, 95% CI 1.25-1.38), connective tissue disorders (adjusted OR 1.39, 95% CI 1.19-1.62), epilepsy (adjusted OR 1.37, 95% CI 1.08-1.74) and mood disorders (adjusted OR 1.25, 95% CI 1.11-1.41). The same pattern held for mild forms of congenital heart disease. A higher prevalence of severe congenital heart disease was seen only among offspring of mothers with congenital heart defects or type 2 diabetes.

INTERPRETATION

The children of women with several kinds of chronic disease appear to be at risk for congenital heart disease. Preconception counselling and optimum treatment of pregnant women with chronic disease would seem prudent.

Treatment for epilepsy in pregnancy: neurodevelopmental outcomes in the child

BACKGROUND

Accumulating evidence suggests an association between prenatal exposure to antiepileptic drugs (AEDs) and increased risk of both physical anomalies and neurodevelopmental impairment. Neurodevelopmental impairment is characterised by either a specific deficit or a constellation of deficits across cognitive, motor and social skills and can be transient or continuous into adulthood. It is of paramount importance that these potential risks are identified, minimised and communicated clearly to women with epilepsy.

OBJECTIVES

To assess the effects of prenatal exposure to commonly prescribed AEDs on neurodevelopmental outcomes in the child and to assess the methodological quality of the evidence.

SEARCH METHODS

We searched the Cochrane Epilepsy Group Specialized Register (May 2014), Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (2014, Issue 4), MEDLINE (via Ovid) (1946 to May 2014), EMBASE (May 2014), Pharmline (May 2014) and Reprotox (May 2014). No language restrictions were imposed. Conference abstracts from the last five years were reviewed along with reference lists from the included studies.

SELECTION CRITERIA

Prospective cohort controlled studies, cohort studies set within pregnancy registers and randomised controlled trials were selected for inclusion. Participants were women with epilepsy taking AED treatment; 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 (RB, JW and JG) independently selected studies for inclusion. Data extraction and risk of bias assessments were completed by five authors (RB, JW, AS, NA, AJM). The primary outcome was global cognitive functioning. Secondary outcomes included deficits in specific cognitive domains or prevalence of neurodevelopmental disorders. Due to substantial variation in study design and outcome reporting only limited data synthesis was possible.

MAIN RESULTS

Twenty-two prospective cohort studies were included and six registry based studies. Study quality varied. More recent studies tended to be larger and to report individual AED outcomes from blinded assessments, which indicate improved methodological quality.The developmental quotient (DQ) was lower in children exposed to carbamazepine (CBZ) (n = 50) than in children born to women without epilepsy (n = 79); mean difference (MD) of -5.58 (95% confidence interval (CI) -10.83 to -0.34, P = 0.04). The DQ of children exposed to CBZ (n = 163) was also lower compared to children of women with untreated epilepsy (n = 58) (MD -7.22, 95% CI -12.76 to - 1.67, P = 0.01). Further analysis using a random-effects model indicated that these results were due to variability within the studies and that there was no significant association with CBZ. The intelligence quotient (IQ) of older children exposed to CBZ (n = 150) was not lower than that of children born to women without epilepsy (n = 552) (MD -0.03, 95% CI -3.08 to 3.01, P = 0.98). Similarly, children exposed to CBZ (n = 163) were not poorer in terms of IQ in comparison to the children of women with untreated epilepsy (n = 87) (MD 1.84, 95% CI -2.13 to 5.80, P = 0.36). The DQ in children exposed to sodium valproate (VPA) (n = 123) was lower than the DQ in children of women with untreated epilepsy (n = 58) (MD -8.72, 95% -14.31 to -3.14, P = 0.002). The IQ of children exposed to VPA (n = 76) was lower than for children born to women without epilepsy (n = 552) (MD -8.94, 95% CI -11.96 to -5.92, P < 0.00001). Children exposed to VPA (n = 89) also had lower IQ than children born to women with untreated epilepsy (n = 87) (MD -8.17, 95% CI -12.80 to -3.55, P = 0.0005).In terms of drug comparisons, in younger children there was no significant difference in the DQ of children exposed to CBZ (n = 210) versus VPA (n=160) (MD 4.16, 95% CI -0.21 to 8.54, P = 0.06). However, the IQ of children exposed to VPA (n = 112) was significantly lower than for those exposed to CBZ (n = 191) (MD 8.69, 95% CI 5.51 to 11.87, P < 0.00001). The IQ of children exposed to CBZ (n = 78) versus lamotrigine (LTG) (n = 84) was not significantly different (MD -1.62, 95% CI -5.44 to 2.21, P = 0.41). There was no significant difference in the DQ of children exposed to CBZ (n = 172) versus phenytoin (PHT) (n = 87) (MD 3.02, 95% CI -2.41 to 8.46, P = 0.28). The IQ abilities of children exposed to CBZ (n = 75) were not different from the abilities of children exposed to PHT (n = 45) (MD -3.30, 95% CI -7.91 to 1.30, P = 0.16). IQ was significantly lower for children exposed to VPA (n = 74) versus LTG (n = 84) (MD -10.80, 95% CI -14.42 to -7.17, P < 0.00001). DQ was higher in children exposed to PHT (n = 80) versus VPA (n = 108) (MD 7.04, 95% CI 0.44 to 13.65, P = 0.04). Similarly IQ was higher in children exposed to PHT (n = 45) versus VPA (n = 61) (MD 9.25, 95% CI 4.78 to 13.72, P < 0.0001). A dose effect for VPA was reported in six studies, with higher doses (800 to 1000 mg daily or above) associated with a poorer cognitive outcome in the child. We identified no convincing evidence of a dose effect for CBZ, PHT or LTG. Studies not included in the meta-analysis were reported narratively, the majority of which supported the findings of the meta-analyses.

AUTHORS' CONCLUSIONS

The most important finding is the reduction in IQ in the VPA exposed group, which are sufficient to affect education and occupational outcomes in later life. However, for some women VPA is the most effective drug at controlling seizures. Informed treatment decisions require detailed counselling about these risks at treatment initiation and at pre-conceptual counselling. We have insufficient data about newer AEDs, some of which are commonly prescribed, and further research is required. Most women with epilepsy should continue their medication during pregnancy as uncontrolled seizures also carries a maternal risk.

Chronic developmental exposure to phenytoin has long-term behavioral consequences

Anti-epileptic compounds have been linked to several developmental disorders. Specifically, fetal exposure to phenytoin is linked to fetal hydantoin syndrome in humans. We have developed a rat model of fetal hydantoin syndrome in an effort to explore the relationship between drug exposure, development, and learning and memory. Previous studies of this animal model have used various embryological periods of exposure; however, the human syndrome is reported in the offspring of mothers that maintain drug regimens throughout gestation and nursing. To that end, the present study investigated associative learning in rats exposed to therapeutic levels of phenytoin throughout prenatal development and the postnatal pre-weaning period. We used an instrumental appetitive-to-aversive transfer paradigm, which has hippocampal-dependent components, and an avoidance-conditioning paradigm to test simple associative learning and higher-order learning and memory. Compared to controls, we report increased rates of acquisition and performance by the phenytoin group in both the appetitive and the avoidance learning paradigm, and a substantial impairment in avoidance learning following the transfer from appetitive to aversive conditioning. The positive deficit observed with simple associative learning and the negative transfer effect associated with higher order learning suggests that chronic exposure to phenytoin throughout gestation disrupts hippocampal development, which subsequently leads to impaired function in adulthood.

Noninherited risk factors and congenital cardiovascular defects: current knowledge: a scientific statement from the American Heart Association Council on Cardiovascular Disease in the Young: endorsed by the American Academy of Pediatrics

Prevention of congenital cardiovascular defects has been hampered by a lack of information about modifiable risk factors for abnormalities in cardiac development. Over the past decade, there have been major breakthroughs in the understanding of inherited causes of congenital heart disease, including the identification of specific genetic abnormalities for some types of malformations. Although relatively less information has been available on noninherited modifiable factors that may have an adverse effect on the fetal heart, there is a growing body of epidemiological literature on this topic. This statement summarizes the currently available literature on potential fetal exposures that might alter risk for cardiovascular defects. Information is summarized for periconceptional multivitamin or folic acid intake, which may reduce the risk of cardiac disease in the fetus, and for additional types of potential exposures that may increase the risk, including maternal illnesses, maternal therapeutic and nontherapeutic drug exposures, environmental exposures, and paternal exposures. Information is highlighted regarding definitive risk factors such as maternal rubella; phenylketonuria; pregestational diabetes; exposure to thalidomide, vitamin A cogeners, or retinoids; and indomethacin tocolysis. Caveats regarding interpretation of possible exposure-outcome relationships from case-control studies are given because this type of study has provided most of the available information. Guidelines for prospective parents that could reduce the likelihood that their child will have a major cardiac malformation are given. Issues related to pregnancy monitoring are discussed. Knowledge gaps and future sources of new information on risk factors are described.

Phenytoin teratogenicity: Hypoxia marker and effects on embryonic heart rhythm suggest an hERG-related mechanism

BACKGROUND

The antiepileptic drug phenytoin (PHT) is a human and animal teratogen. The teratogenicity has been linked to PHT-induced embryonic cardiac arrhythmia and hypoxic damage during a period when regulation of embryonic heart rhythm is highly dependent on a specific K(+) ion current (I(Kr)). PHT has been shown to inhibit I(Kr). The aims of this study were to investigate whether teratogenic doses cause embryonic hypoxia during and after the I(Kr) susceptible period and to further characterize PHT effects on embryonic heart rhythm.

METHODS

Pregnant C57BL mice were administered the hypoxia marker pimonidazole followed by PHT or saline (controls) on GD 10 or GD 15. The embryos were fixed and sectioned, and the immunostained sections were analyzed with a computer assisted image analysis. Effects of PHT (0-250 microM) on heart rhythm in GD 10 embryos cultured in vitro were videotaped and then analyzed by using a digitalization technique.

RESULTS

PHT dose-dependently increased the hypoxia staining (6- and 11-fold after maternal dosing of 100 and 150 mg/kg, respectively) during the period I(Kr) is expressed and functional (GD 10). In contrast, there were no differences between the PHT doses in hypoxia staining, and much less pronounced hypoxia after this period (GD 15). With increasing PHT concentrations, increased length of the interval (bradycardia) and large variations in length between individual heartbeats (arrhythmia) were recorded.

CONCLUSIONS

PHT induced bradycardia/arrhythmia and severe embryonic hypoxia during the I(Kr) susceptible period, supporting the idea of an I(Kr)-arrhythmia-hypoxia-related teratogenic mechanism.

Neonatal phenobarbital imprints overexpression of cytochromes P450 with associated increase in tumorigenesis and reduced life span

Perinatal exposure to phenobarbital produces a range of permanent reproductive, growth, locomoter, and learning dysfunctions in animals as well as humans. In addition, the affected individuals exhibit latently expressed (i.e., postpubertal) above normal activity levels of hepatic multicytochrome P450-dependent drug metabolizing enzymes. We report that in spite of apparent normal health for the better part of their lives, daily administration of therapeutic-like doses of phenobarbital to male and female rat pups during the first postpartum week reduced life expectancy by approximately 20%. Necropsy at the time of natural death revealed an associated two- to threefold increase in the incidence of tumors in barbiturate-exposed rats of both sexes and a three- to fourfold increase in urinary tract pathologies in male rats. At 2 yr of age, in agreement with an overexpression of hepatic CYP2C6 and CYP2C7, both in vitro and in vivo drug metabolism was more rapid in the phenobarbital-imprinted male and female animals. Moreover, when the senescent rats were rechallenged with a nominal dose of the barbiturate, males and females neonatally exposed to phenobarbital exhibited a dramatic overinduction of multicytochrome P450-dependent drug metabolizing enzymes as well as an overexpression of individual isoforms of cytochrome P450 implicated in enhanced susceptibility to tumorigenesis. Our findings support the growing realization that many adult diseases have their origins in early life by emphasizing that unlike adults, the new born is "plastic," and even therapeutic drugs may produce "silent" programming defects that subtly, but irrevocably, jeopardize life-long well-being.

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.

Structural Effects and Neurofunctional Sequelae of Developmental Exposure to Psychotherapeutic Drugs: Experimental and Clinical Aspects

The advent of psychotherapeutic drugs has enabled management of mental illness and other neurological problems such as epilepsy in the general population, without requiring hospitalization. The success of these drugs in controlling symptoms has led to their widespread use in the vulnerable population of pregnant women as well, where the potential embryotoxicity of the drugs has to be weighed against the potential problems of the maternal neurological state. This review focuses on the developmental toxicity and neurotoxicity of five broad categories of widely available psychotherapeutic drugs: the neuroleptics, the antiepileptics, the antidepressants, the anxiolytics and mood stabilizers, and a newly emerging class of nonprescription drugs, the herbal remedies. A brief review of nervous system development during gestation and following parturition in mammals is provided, with a description of the development of neurochemical pathways that may be involved in the action of the psychotherapeutic agents. A thorough discussion of animal research and human clinical studies is used to determine the risk associated with the use of each drug category. The potential risks to the fetus, as demonstrated in well described neurotoxicity studies in animals, are contrasted with the often negative findings in the still limited human studies. The potential risk fo the human fetus in the continued use of these chemicals without more adequate research is also addressed. The direction of future research using psychotherapeutic drugs should more closely parallel the methodology developed in the animal laboratories, especially since these models have already been used extremely successfully in specific instances in the investigation of neurotoxic agents.

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.

Can We Ensure the Safe Use of Known Human Teratogens?

The prescription of known teratogenic medications requires a careful balance between allowing women access to medications that they might need and avoiding unnecessary exposure to these medications during pregnancy because of their devastating fetal effects. Isotretinoin, a potent human teratogen, is of particular concern because of its widespread use among reproductive-aged women and the dramatic increase in use from 1992 through 2000. A revised risk management system was implemented in 2002 because of concerns about the continued occurrence of isotretinoin-exposed pregnancies. However, the recent approval of three generic versions of isotretinoin in the US has further complicated risk management and raises concerns that use might increase further if the lower cost of generics serves to increase accessibility. There are now four separate isotretinoin risk management systems in the US, each with its own distinct packaging, though the requirements for and substance of each are identical. Some additional concrete steps could be taken to minimise any unnecessary use of isotretinoin and help allow an adequate assessment of the current risk management systems. In addition to being familiar with and following all aspects of the current risk management system, physicians could choose to limit the use of isotretinoin to those who meet the labelled indications in order to reduce the number of exposed pregnancies. All four companies currently marketing isotretinoin in the US could jointly and voluntarily establish a consolidated, mandatory registration and follow-up of all women of reproductive potential who receive an isotretinoin prescription. Mandatory registration has many challenges, but it could allow a clear accounting of the total number of women for whom follow-up information is and is not available. Although the companies cannot be legally compelled to use a consolidated approach, the use of a single registry for the originator's product and all generic brands would allow identification of duplicates and also avoid the confusion that is introduced by providing materials that not only look different, but also have different addresses, contact information and names for participation in follow-up surveys. This is particularly important because women might take more than one version of isotretinoin during a single course of therapy or might receive a different programme's materials from their doctor than from the pharmacy. Though the introduction of generic versions of isotretinoin further complicates risk management, the companies marketing isotretinoin have an opportunity to work together to demonstrate their commitment to both limit the occurrence of exposed pregnancies and conduct a meaningful evaluation of the occurrence of pregnancies exposed to isotretinoin.

Effects on toes from prenatal exposure to anticonvulsants

BACKGROUND

Changes in the distal phalanges of the fingers, including coned epiphyses and hypoplasia of the phalanges, are recognized teratogenic effects of the anticonvulsant drugs phenytoin and phenobarbital. We hypothesized that the frequency of these changes would also be increased in the toes of children exposed to these drugs in comparison to unexposed children.

METHODS

We report on the findings in an analysis of radiographs of the feet of 63 children exposed in utero to either phenytoin alone, phenobarbital alone or both drugs and 56 unexposed comparison children.

RESULTS

Only subtle changes were identified. The frequency of coned epiphyses and hypoplasia of phalanges of the toes was the same in both the anticonvulsant and unexposed children. Among the anticonvulsant-exposed children, however, there was a strong association between the presence of coned epiphyses in the feet and in the hands: all five children with coned epiphyses in the hands, as described previously in the same individuals by Lu et al. ([2000] Teratology 61:277-283) had coned epiphyses in their feet (P = 0.0012). Measurements showed a shortening of metatarsals in all three treatment groups, but this was significant only in the phenytoin monotherapy-exposed children.

CONCLUSIONS

Subtle changes are present in the phalanges and metatarsals of the feet of anticonvulsant-exposed children, but the overall frequency is much less than occurred in the hands of the same children. We conclude that the presence of either coned epiphyses or hypoplasia of the phalanges of the toes cannot be considered a distinctive feature of the teratogenicity of the anticonvulsant drugs phenytoin and phenobarbital.

Effect of prenatal exposure to anticonvulsant drugs on dermal ridge patterns of fingers

BACKGROUND

An altered frequency of specific dermal ridge patterns on fingertips, such as an increased number of arches, has been observed in children exposed in utero to anticonvulsants and other teratogens. Asymmetry of the distribution of dermal ridge patterns has been attributed to environmental exposures and genetic factors.

METHODS

We evaluated all of the dermal ridge patterns of 66 children who had been exposed to either the anticonvulsant phenytoin alone or phenytoin and phenobarbital. We determined the frequency of each pattern, concordance between the fingers on the left and right hands, sex differences and total ridge counts in the drug-exposed children and compared them to the findings in 716 unexposed comparison children. The frequency of each pattern was established in comparison to the most common type of pattern (ulnar loop), which showed that there were alterations in the frequency of arches, radial loops and whorls on specific fingers.

RESULTS

Eight (12.1%) of 66 children had three or more arch patterns, with all but one having been exposed to phenytoin and phenobarbital. Only one of these eight children was considered by the masked examiner to have fingernail hypoplasia. There was no evidence of asymmetry in the anticonvulsant-exposed children. There were minor differences in the distribution of total ridge count.

CONCLUSIONS

Subtle differences in several dermal ridge patterns, not just arch patterns, were present in anticonvulsant-exposed children, primarily in those exposed to polytherapy: phenytoin and phenobarbital.

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).

Vitamin E decreases valproic acid induced neural tube defects in mice

The present study was undertaken to investigate the effect of vitamin E on valproic acid (VPA) induced teratogenesis. Pregnant Balb mice were divided into six groups of 10-11 animals each. The mice in group 1 served as control and were injected with saline subcutaneously on day 8 of gestation, whereas, animals in group 2 received a single injection of VPA (700 mg/kg (s.c.)). Groups 3 and 4 received an oral administration of vitamin E in the doses of 250 and 500 mg/kg, respectively, 1 h before VPA injection. Group 5 and 6 were given vitamin E only, in the same doses as group 3 and 4. On day 18 of gestation, the mice were killed by cervical dislocation. Embryotoxicity was assessed by counting the number of implants, live and dead fetuses, resorptions, crown rump length and fetal body weight. The fetuses were observed for malformations including neural tube defects (excencephaly), open eye lid and micrognathae. VPA administration resulted in a significant reduction of the average live fetuses/litter, fetal weight and crown rump length and a significant increase in malformations (excencephaly, open eye lid and micrognathae). Concomitant administration of vitamin E significantly attenuated VPA induced decrease in the fetal weight, crown rump length and malformations.

Prenatal phenytoin exposure and spatial navigation in offspring: effects on reference and working memory and on discrimination learning

Previous research has shown that rats exposed to phenytoin (PHT) in utero demonstrate abnormal circling, decreased learning, hyperactivity, and delayed air righting reflex development. The effects of prenatal PHT on offspring learning have been found on multiple-T mazes (Biel and Cincinnati types) and on spatial navigation (Morris maze). However, the specificity of the latter effects is unknown. Herein, we tested the effects of prenatal PHT in a Morris maze using six different procedures: cued versus spatial reference memory-based learning, cued versus spatial working memory-based learning, and cued versus spatial discrimination learning. PHT-exposed offspring showed increased preweaning mortality, growth reduction, and abnormal circling as noted in previous studies. PHT offspring were separated into those exhibiting circling and those not. PHT noncircling offspring demonstrated impaired reference memory-based spatial learning (acquisition and reversal), but no other effects. By contrast, PHT circling offspring demonstrated not only impaired reference memory-based spatial learning, but also impaired cued platform learning, impaired spatial discrimination, and impaired working memory-based learning. These data confirm that prenatal PHT induces a specific reference memory-based spatial learning deficit even in asymptomatic (noncircling) offspring that is distinct from the impairment induced in littermates exhibiting the circling impairment.

Developmental neurotoxicity of phenytoin on granule cells and Purkinje cells in mouse cerebellum

Phenytoin (PHT) is a primary antiepileptic drug. Cerebellar malformations in human neonates have been described following intrauterine exposure to PHT. The neonatal period of development in the cerebellum in mice corresponds to the last trimester in humans. To examine the neurotoxic effects of PHT in the developing cerebellum, we administered PHT orally to newborn mice once a day during postnatal days 2-4. We observed many apoptotic cells in the external granular layer (EGL) on postnatal day 5, labeled cells in the EGL still remaining 72 h after labeling with 5-bromo-2'-deoxyuridine, and EGL thicker than that in the control on postnatal day 14. These results showed that PHT induced cell death of external granule cells and inhibited migration of granule cells in cerebella. In specimens immunostained with antibody against inositol 1,4,5-trisphosphate receptor type 1, Purkinje cells in the treated group had poor and immature arbors, and partially showed an irregular arrangement. The motor performance of the treated mice in a rotating rod test was impaired, although there were no changes in muscular strength or in walking pattern at the period of maturity. These findings indicate that PHT induces neurotoxic damage to granule cells and Purkinje cells in the developing cerebellum and impairs selected aspects of motor coordination ability.

Neurologic care of pregnant women with epilepsy

Epilepsy is a common neurologic condition in women of reproductive age. Although their risks are greater than those for women in the general population, the majority of women with epilepsy have a good pregnancy outcome. An understanding of the risks and appropriate management of both the pregnancy and epilepsy in these patients is essential for their physicians. Health-care providers should discuss contraception and reproductive issues with all of their female patients with epilepsy as they enter reproductive age. Optimal care requires prepregnancy counseling, including information about contraception, dietary folate supplementation, and the risks related to pregnancy. Although antiepileptic drugs (AEDs) have been implicated as the major cause of teratogenesis in infants born to mothers with epilepsy, uncontrolled epilepsy is also associated with maternal and fetal risk. Therefore, optimal seizure control during pregnancy remains an important goal for women with epilepsy. Women with epilepsy should be counseled about breast-feeding their infants and supported in their decision. The recommendations in this article reflect those of a Practice Parameter developed by the American Academy of Neurology Quality Standards Subcommittee.

Neurotoxic effects of phenytoin on postnatal mouse brain development following neonatal administration

Phenytoin (PHT) is a commonly used anticonvulsant drug. It has been reported that children exposed prenatally to PHT have brain malformations and psychomotor dysfunction. The neonatal development of the central nervous system (CNS) in mice corresponds to the last trimester in humans. To examine the neurotoxic effects of PHT on postnatal brain development, we administered PHT at doses of 10, 17.5, 25, or 35 mg/kg to newborn mice once a day during postnatal days (PD) 2-4. These dose levels result in plasma levels corresponding to the therapeutic ranges in humans. We measured the weight of total brain, cerebrum, cerebellum, and brain stem on PD 5 through 21, and examined early motor functions including head elevation, elevation of pelvis, pivoting, crawling, and righting reflex . Total brain weight, cerebral weight, and cerebellar weight in the group treated with 25 or 35 mg/kg were significantly reduced compared to controls from PD 5 to 21. Mice treated with PHT at 25 or 35 mg/kg showed decreased locomotor abilities and righting reflex on PD 5. In all phenytoin treatment groups, phenytoin levels in the brain were higher than those in the plasma on the third day of PHT treatment. We thus observed neurotoxic effects of PHT on postnatal brain development in mice. Our present data may provide useful implications for the management of PHT-induced developmental neurotoxicity and evaluation of psychomotor development in children exposed to PHT during the late fetal period.

Effects of low-dose phenytoin administered to newborn mice on developing cerebellum

To examine correlations between dose levels of phenytoin (PHT) and neurotoxic effects on cerebellar development, we administered 10, 17.5, 25, and 35 mg/kg PHT suspended in sesame oil orally to newborn Jcl:ICR mice once a day during postnatal days 2-4 and determined plasma PHT concentrations during the administration period. Mortality rates were 12.5% and 35.2% in males and 15.3% and 33.3% in females for the 25 and 35 mg/kg PHT-treated groups during the PHT treatment, respectively. In the 25 and 35 mg/kg PHT-treated groups, total brain weight, the size of the cerebellum, and cerebellar weight were significantly reduced on postnatal day 21. However, in the 10 and 17.5 mg/kg PHT-treated groups, total brain weight and the size and weight of the cerebellum did not differ from those of the control group. Histologically, the number of pyknotic cells in the external granular layer (EGL) in the 25 and 35 mg/kg PHT-treated groups was increased on postnatal day 5, and the EGL was thicker than in the control group on postnatal day 14. Some of the Purkinje cells in the 35 mg/kg PHT-treated group showed degeneration. Plasma PHT levels were 10.7 +/- 2.2 and 24.6 +/- 2.6 micrograms/ml in the 25 and 35 mg/kg PHT groups on the third day of PHT treatment, respectively. In the 25 mg/kg PHT group, plasma PHT level was found to be in the therapeutic range for humans, 10-20 micrograms/ml. Accordingly, during pregnancy, epileptic women should be carefully given PHT at the lowest effective dose while plasma PHT levels are monitored properly. These findings emphasize the importance of pharmacokinetics in evaluating of phenytoin-induced developmental neurotoxicity.

Serial examination of 20,248 newborn fetuses and infants: correlations between drug exposure and major malformations

Maternal medication during the first trimester of pregnancy has been discussed as a risk factor for development of birth defects. The correlation between maternal drug use and major malformations was investigated in a population-based case-control study in Mainz. Over a period of 5 years (1990-1994), 20,248 livebirths, stillbirths, and abortions underwent physical and sonographic examination, and anamnestic data were collected. A total of 1,472 births with congenital anomalies (cases) and 9,682 births without major and minor malformations (controls) were analyzed. We distinguished between 30 different drug categories, which were divided into medication taken continuously (before and during pregnancy; CM) and acute medication (drugs given within the first 3 months of gravidity; AM). Statistically highly-significant results [CM: Odds Ratios (OR) 1.2, Confidence Intervals (CI) 1.1-1.4, P = 0.008; AM: OR 1.2, CI 1.1-1.3, P = 0.008] were established for maternal drug use in correlation to birth defects. For the majority of combinations between drugs and specific malformations no teratogenic risks were found. However, statistically significant associations were recorded for antiallergics and heart anomalies (CM, AM) as well as musculoskeletal anomalies (AM); for bronchodilators and heart anomalies (CM, AM); for antiepileptics and anomalies of the internal urogenital system (CM), as well as cleft palate/cleft lips (AM); for thyroid hormones and anomalies of the nervous system (CM, AM), as well as anomalies of the external urogenital system (CM, AM); for insulin and anomalies of the musculoskeletal system (CM); for digitalis and anomalies of the musculoskeletal system (AM).

Phenytoin causes phalangeal hypoplasia in the rabbit fetus at clinically relevant free plasma concentrations

New Zealand White rabbits were treated orally with 0 (controls), 50, 100, or 150 mg/kg phenytoin on days 14-16 of pregnancy. Total and free plasma concentrations of phenytoin were determined in maternal plasma 2, 6, and 24 hr after the final dose in all animals. In addition, after administration of 150 mg/kg maternal plasma concentrations were also determined after 12 and 48 hr, the concentrations in amniotic fluid after 6 hr, and those in fetal tissue 6 and 24 hr after the final treatment. A high degree of plasma protein binding was observed in maternal blood. Treatment with 50 mg/kg resulted in free plasma concentrations of up to 5.0 mumol/l during the 24 hr period following the final dose. Significantly higher free plasma concentrations were observed at the two higher dose levels; up to 9.7 mumol/l at 100 mg/kg and 12.7 mumol/l at 150 mg/kg. Digital hypoplasia was not seen in the control group or the animals treated with 50 mg/kg. However, treatment with 100 mg/kg resulted in hypoplasia in a single or a few digits in approximately 50% of the fetuses, and 150 mg/kg provoked hypoplasia in almost all digits in all fetuses. These results show that even though the doses which caused digital defects in rabbits are much higher than those used therapeutically, the resulting free concentrations of phenytoin are similar to those which are associated with the same type of defects in humans. These data indicate that the pharmacologically induced fetal hypoxia/ischemia and vascular disruption preceding malformations of this type, which were observed in a previous study in rabbits, may be of human relevance.

Prenatal exposure to phenytoin, facial development, and a possible role for vitamin K

Ten patients with maxillonasal hypoplasia (Binder "syndrome"), who were prenatally exposed to phenytoin (usually in combination with other anticonvulsants), were identified retrospectively. In addition to their facial anomalies, 6 of the patients were radiographed neonatally and showed punctate calcification, characteristic of chondrodysplasia punctata. Evidence is presented that the facial abnormalities seen in these children are due to anticonvulsant-induced vitamin K deficiency, causing abnormal development of the cartilaginous nasal septum. We propose that early vitamin K supplementation of at-risk pregnancies may prevent the development of maxillonasal hypoplasia, which in some patients is severely disfiguring and causes great emotional distress. Correction of this facial defect requires surgical and dental treatment over a long period of time.

Neurotoxicity of phenytoin administered to newborn mice on developing cerebellum

To examine the neurotoxic effects of phenytoin (PHT) on cerebellar development, we administered 50 mg/kg PHT suspended in sesame oil orally to newborn Jcl:ICR mice once a day during postnatal days 2-14 and determined plasma PHT concentrations at designated intervals during the administration period. In the treated group, walking reflex and negative geotaxis were poorly developed on postnatal day 14. Pyknotic cells in the external granular layer (EGL) significantly increased and were prominent in the vermis area compared with controls on postnatal day 14. Plasma PHT levels were 34-36 micrograms/ml on the 3rd day of PHT treatment and approached a steady-state situation. Total brain weight, size of the cerebellum, and cerebellar weight were significantly reduced in the treated group on postnatal day 56. Accordingly, oral administration of PHT in the neonatal period induced neurotoxic damage on the developing cerebellum.

Identical phalangeal defects induced by phenytoin and nifedipine suggest fetal hypoxia and vascular disruption behind phenytoin teratogenicity

In previous experimental studies in rabbits, we have shown that vasodilating drugs (including nifedipine) cause distal digital defects. These defects were preceded by edema, hemorrhage, and finally necrosis of the developed cartilage in the phalanges. The underlying mechanism is most likely a fetal hypoxic response, secondary to maternal hypotension and decreased uteroplacental blood flow. Since phenytoin is known to cause distal digital defects both in man and rabbits, we decided to compare the defects provoked by oral administration of phenytoin (100 mg/kg) versus nifedipine (8.3 mg/kg) to New Zealand White rabbits on days 6-18 of gestation. In order to investigate phase-specificity, phenytoin (150 mg/kg) was given on days 14-17. The result of single dose administration on day 16 of phenytoin (300 mg/kg) versus nifedipine (33.2 mg/kg) was also studied. In this latter experiment maternal heart rate was measured up to 21 hours after phenytoin administration. Phenytoin induced digital defects identical with those produced by nifedipine and caused marked maternal cardiodepression. The defects consisted of a reduction, absence, or abnormal structure of the distal phalanges. The distal phalanx of the fourth digit on the hindpaw was the first to be affected, with inclusion of other phalanges, both on the hind- and forepaws, with increasing dose. The sensitive period for induction and histological appearance of these defects was identical for phenytoin and nifedipine. These results suggest that vascular disruption due to a fetal hypoxic response lies behind phenytoin teratogenicity, as has been shown for vasodilators. A cardiodepressive action on the maternal and fetal hearts, possibly in combination with decreased uteroplacental blood flow, is discussed as a probable factor behind phenytoin teratogenicity.

Fetal phenytoin exposure, hypoplastic nails, and jitteriness

In a prospective study infants born to mothers with epilepsy (n = 61) were found to have an unexpectedly high incidence of congenital anomalies (26/61, 43%) and neonatal conditions (26/61, 43%) compared with controls (0/62, and 6/62, 10%, respectively). There were two neonatal deaths in the study group but none among the controls. Hypoplasia of the finger or toenails was a common congenital anomaly in those infants whose mothers had received phenytoin alone or in combination with other anticonvulsant drugs (11 of 40, 28%). The mean serum phenytoin concentration was higher among mothers of infants with hypoplastic nails than among those with normal nails. Jitteriness was a common neonatal condition affecting infants of epileptic mothers (11 of 61, 18%) but not controls The mean cord serum phenytoin concentrations were similar among jittery and non-jittery infants. At follow up (after excluding one infant with Down's syndrome from the study group) the infants seemed to have developed normally, though one had serious learning difficulties at school. We suggest that hypoplasia of the nails is related to high maternal serum concentrations of phenytoin, and though 18% of infants born to epileptic mothers were jittery compared with no control infants this may not be the result of withdrawal of the drug in all cases.

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)

Developmental neurotoxicity of anticonvulsants: human and animal evidence on phenytoin

Most epileptic women delivering children each year take anticonvulsants throughout pregnancy. The teratogenic potential of anticonvulsants is most notable for phenytoin, trimethadione, valproic acid, and carbamazepine. This review focuses on the human and animal evidence for the teratogenicity of phenytoin, with emphasis on neurobehavioral end points. The Fetal Hydantoin Syndrome (FHS) consists of craniofacial defects and any two of the following: pre/postnatal growth deficiency, limb defects, major malformations, and mental deficiency. Available data suggest a prevalence of FHS of 10-30% in infants of women ingesting 100-800 mg/kg of phenytoin during the first trimester or beyond. Unfortunately, data on neurobehavioral development in FHS children is limited. Animal models of FHS have been developed and those focusing on neurobehavioral effects are reviewed. Phenytoin produces multiple behavioral dysfunctions in rat offspring at subteratogenic and nongrowth retarding doses. These behaviorally teratogenic doses produce maternal serum phenytoin concentrations in rats comparable to those found in humans. The dysfunctions in rats are dose-dependent and exposure-period-dependent, but independent of nutritional, maternal rearing, or seizure disorder confounds. Effects include vestibular dysfunction, hyperactivity and deficits in learning and memory. General comparability between the human and animal findings for phenytoin are apparent, however, difficulties with existing studies prevent precise comparisons. Animal studies have not dealt satisfactorily with the potential contribution of epileptic disease state to the FHS, with fetal brain drug concentration determinations, a complete dose-effect range, effects in multiple species (although limited nonhuman primate data exist), site of CNS injury, and the comparability of end points assessed. Human studies have not dealt satisfactorily with issues of the need for prospective study designs, separation of the effects of different anticonvulsants, or adequate long-term follow-up of cases, especially with attention to neuropsychological assessment.

Head circumference in children of epileptic mothers: contributions of drug exposure and genetic background

Head circumference after the first year of life was investigated in 144 children of epileptic mothers ('study group'). Fifty-two children had been exposed to phenytoin monotherapy, 19 to carbamazepine monotherapy, 27 to drug combinations including barbiturates, 29 to other drug combinations, and 17 children had not been exposed to antiepileptic drugs (AEDs) during pregnancy. The prevalence of microcephaly (2.1%) was no higher than that in the general population. Head circumference was measured at 5.5 years in 121 of the study group children, in 105 control children, and in the majority of their parents (118 mothers and 89 fathers in the study group, and 103 mothers and 65 fathers in the control group). The sex-adjusted head circumferences of the children showed a significant variation according to exposure subgroup, with the barbiturate and carbamazepine monotherapy exposed children having the lowest mean values. This result is similar to our previous findings in the same children at birth and at 18 months of age. Paternal head circumference was also below average in the same subgroups. After further adjustment for parental head circumference, the significant variation between the subgroups of children disappeared, even though the barbiturate exposed children continued to have the lowest mean value. Genetic causes may thus contribute to the relatively small head circumference in some AED exposed children of epileptic mothers. However, a mild drug effect in the barbiturate and carbamazepine exposed children cannot be excluded.

Distal phalangeal hypoplasia in children with prenatal phenytoin exposure: results of a controlled anthropometric study

Phalangeal and metacarpal bone length was measured from hand radiographs in 111 children of epileptic mothers and 96 control children of nonepileptic mothers. Seventy-six children of the study group had been exposed to phenytoin in the first 20 weeks of pregnancy, 21 had been exposed to other anti-epileptic drugs excluding phenytoin, and 14 had not been exposed. Distal phalangeal lengths were significantly reduced in phenytoin-exposed children. The second and fifth digits were most affected. Phenytoin exposure was associated with a significantly elevated prevalence (11%) of radiologically defined distal phalangeal hypoplasia. The subgroup of children exposed to phenytoin levels over 40 mumol/l showed more prominent effects than did the subgroup exposed to lower or unknown concentrations. These results confirm that early fetal exposure to phenytoin decreases distal phalangeal size, as suggested by several previous studies relying on clinical examination only. Distal phalangeal hypoplasia was not accompanied by other serious abnormalities.

Developmental toxicity and pharmacokinetics of oral and intravenous phenytoin in the rat

Correlations between oral and intravenous (i.v.) doses of phenytoin, maternal plasma levels, and subsequent developmental toxicity were examined in the Sprague-Dawley rat. Oral administration of 150 to 1500 mg/kg and i.v. administration of 25 to 100 mg/kg phenytoin from gestational days (GD) 8 to 17 resulted in a dose-dependent increase in maternal death and toxicity [impaired motor function, decreased maternal weight gain (oral dose only)], embryolethality, and intrauterine growth retardation, in addition to significant increases in craniofacial (1125 mg/kg oral; 75 mg/kg i.v.) and urogenital (1125 mg/kg oral) malformations. Pharmacokinetic sampling in oral and i.v. groups on GD 8-9 and 16-17 revealed significant increases in maternal drug exposure over the treatment period, as evidenced by 2- to 3-fold increases in total plasma phenytoin (bound + free) half-life, area under the concentration curve, peak concentration (oral dose only), and decreases in clearance. These findings emphasize the importance of pharmacokinetics in the evaluation of phenytoin-induced developmental toxicity.

Prenatal phenytoin exposure decreases neuronal membrane order in rat offspring hippocampus

Pregnant Sprague-Dawley CD rats were administered 0 or 200 mg/kg of phenytoin by gavage on days 7-18 of gestation, with controls pair-fed to the phenytoin exposed dams. At birth, litter sizes were standardized to 10, balancing for sex, and were reared by their biological dams until either day 3 or 28. At each of these ages half of the litters from each group were used to determine synaptic plasma membrane order in selected brain regions (cerebellum, cortex, hippocampus) by fluorescence polarization using the probe 1,6-diphenyl-1,3,5-hexatriene (DPH). No significant differences in membrane anisotropy were noted in 3-day-old phenytoin offspring, but a reduction in anisotropy in 28-day-old phenytoin offspring hippocampal regions was observed. The effect was specific in that no changes were found in the cerebellum or cortex at this age. The magnitude of the change corresponded to an approximately 3-5 degrees C increase in temperature and to changes produced by other known membrane disordering agents, such as ethanol. The data, together with previous findings of memory impairments in phenytoin offspring, support an association between the hippocampal membrane disordering effect and functional impairments produced by prenatal phenytoin exposure.

Facial clefts and congenital heart defects in children of parents with epilepsy: genetic and environmental etiologic factors

Increased prevalence of cleft lip with or without cleft palate (CL(P], isolated cleft palate (CP), and congenital heart defects (CHD) in children of epileptic mothers have been ascribed to early fetal exposure to antiepileptic drugs (AED). However, common genetic factors responsible for both the malformations in question and the epileptic disorder might be of relevance for the increased rate of CL(P), CP, and CHD, rather than the influence of AED. The present review analyzes the literature on genetic and environmental etiologic factors (i.e. AED and epileptic seizures) that have been reported to increase the rate of CL(P), CP, and CHD in children of parents with epilepsy. Our data suggest that genetic factors are of minor importance for the etiology of facial clefts in offspring of epileptic patients. The rate of facial clefts was increased by a factor of 4.7 in children of AED-treated mothers with epilepsy compared with the background population values. Children of fathers with epilepsy and sibs of epileptic patients had no more facial clefts than expected. The rate of CHD in children of mothers and fathers with epilepsy was comparable to population figures. The role of epileptic seizures as a causative factor for CL(P), CP, and CHD is not settled, but seems to be of limited importance. Areas of future research are outlined concerning the teratogenic role of AED and their metabolites, especially on the postnatal intellectual development of the exposed children. Finally, the need for studies on prophylactic measures as well as the necessity of international surveillance systems on new AED teratogenicity are emphasized.

Minor anomalies in offspring of epileptic mothers

In a prospective study, 121 children of mothers with epilepsy (study group) and 105 control children were examined in a blinded fashion at age 5 1/2 years for 80 minor physical anomalies, including nine typical features previously reported characteristic of fetal hydantoin syndrome. Of the study group, 106 children had been exposed to antiepileptic drugs (82 to phenytoin) during pregnancy; 44 (36%) mothers had had generalized convulsions during pregnancy. One hundred fourteen mothers and 87 fathers of study group children and 101 mothers and 58 fathers of control children were also examined. A significant excess of minor anomalies considered characteristic of hydantoin syndrome was observed in children of epileptic mothers and in epileptic mothers, compared with the control group. There was no excess of other minor anomalies studied. Several minor anomalies previously regarded as typical of fetal hydantoin syndrome were shown to be genetically linked to epilepsy. Only hypertelorism and digital hypoplasia were associated with phenytoin exposure. The current concept of the syndrome seems to be incorrect; most of the "typical" characteristics are not caused by phenytoin. None of the phenytoin-exposed children had all of the main characteristics of hydantoin syndrome (typical acrofacial features, intellectual deficiency, growth retardation, and microcephaly). The risk of developmental disturbance associated with intrauterine phenytoin exposure seems to be much lower than the 7% to 11% risk of fetal hydantoin syndrome reported earlier.

Developmental profile of serum androgens and estrous cyclicity of male and female rats exposed, perinatally, to maternally administered phenytoin

Pregnant rats were treated, daily, with either 10, 50 or 100 mg/kg of phenytoin-Na from day 17 of gestation through postpartum day 7. The male and female offspring exposed to the 2 higher doses of phenytoin had smaller body weights at birth than the diluent-treated rats, and this subnormal body weight gain persisted throughout the life of the affected animals. In contrast, the anticonvulsant produced no adverse effects on the developmental profile of serum androstenedione, testosterone and dihydrotestosterone or estrous cyclicity in the exposed male and female offspring, respectively. In spite of the normal concentrations of serum androgens, the seminal vesicles of the adult rats exposed to the 50 and 100 mg/kg doses of phenytoin were significantly smaller than the diluent-treated males.