Possible teratogenicity of valproic acid

Valproic Acid in Pregnancy Revisited: Neurobehavioral, Biochemical and Molecular Changes Affecting the Embryo and Fetus in Humans and in Animals: A Narrative Review

Valproic acid (VPA) is a very effective anticonvulsant and mood stabilizer with relatively few side effects. Being an epigenetic modulator, it undergoes clinical trials for the treatment of advanced prostatic and breast cancer. However, in pregnancy, it seems to be the most teratogenic antiepileptic drug. Among the proven effects are congenital malformations in about 10%. The more common congenital malformations are neural tube defects, cardiac anomalies, urogenital malformations including hypospadias, skeletal malformations and orofacial clefts. These effects are dose related; daily doses below 600 mg have a limited teratogenic potential. VPA, when added to other anti-seizure medications, increases the malformations rate. It induces malformations even when taken for indications other than epilepsy, adding to the data that epilepsy is not responsible for the teratogenic effects. VPA increases the rate of neurodevelopmental problems causing reduced cognitive abilities and language impairment. It also increases the prevalence of specific neurodevelopmental syndromes like autism (ASD) and Attention Deficit Hyperactivity Disorder (ADHD). High doses of folic acid administered prior to and during pregnancy might alleviate some of the teratogenic effect of VPA and other AEDs. Several teratogenic mechanisms are proposed for VPA, but the most important mechanisms seem to be its effects on the metabolism of folate, SAMe and histones, thus affecting DNA methylation. VPA crosses the human placenta and was found at higher concentrations in fetal blood. Its concentrations in milk are low, therefore nursing is permitted. Animal studies generally recapitulate human data.

YouTube as a source of information on preventing the use of valproic acid in women during pregnancy

BACKGROUND

YouTube™ ( http://www.youtube.com ), as a very popular video site worldwide, is increasingly being used as a platform to disseminate health information. The purposes of this review were to assess the overall usefulness of the information on the prevention of valproic acid use in women during pregnancy on YouTube™ for patients.

METHODS

The YouTube™ website was systematically using 8 keywords. One hundred and fifty four videos meet the selection criteria. The researcher evaluated the video duration, days since upload, views and the likes. These videos are categorized as Education, News & Politics and People & Blogs. We designed a usefulness scoring scheme to assess videos quality and classified them as "slightly useful", "useful" and "very useful". The Kruskal-Wallis test was used to determine whether differences existed between total usefulness scores and categories and Pearson chi-square test for categorical variables.

RESULTS

The majority of videos were educational (62.8%). The "People & Blogs" and "News & Politics" videos scored significantly higher, but had no significant difference in days since upload, views, views/day or likes. More than half of the videos (91/154) were categorized as "useful". The mean posted days (p = 0.045) was significantly different in the useful group compared with the slightly useful group. There were no correlation between usefulness and the number of days since upload, duration, views, views/day, or likes.

CONCLUSION

YouTube™ is a promising source of information regarding the use of valproic acid during pregnancy. "News & Politics" videos are the most usefulness. Considering the presence of more slightly useful information, publishers need to improve more comprehensive video content that includes replacement medications, diagnoses and treatments. In the healthcare information space, consumers need to be directed to reliable video.

Valproate: Not All Boxed Warnings Are Created Equal

OBJECTIVE

Valproate has undergone significant changes in labeling to the boxed warnings associated with it. This review will analyze evidence regarding the valproate-boxed warnings for teratogenicity, hepatotoxicity, and pancreatitis, with a particular emphasis on the fetal risk.

DATA SOURCES

A review of Pubmed, Cochrane Central Register, Google Scholar, manufacturer websites, and product labeling was performed from 1963 to February 2022, using the following search terms: valproate, valproic acid, depakote, teratogenicity, birth defects, fetal risk, hepatotoxicity, and pancreatitis. Relevant English-language studies and those conduced in humans were considered. Product labeling was also reviewed.

DATA SYNTHESIS

There is a significant fetal risk following in utero valproate exposure (risk of malformation development: 8.6% in 360 women in North America). Current labeling in the United States recommends co-prescribing effective contraception for women of childbearing age. The risk of hepatotoxicity and pancreatitis is much lower in the general population (1/20 000 and 1/40 000 patients, respectively) compared with those patients with certain risk factors who are taking valproate (1/500).

CONCLUSIONS

Overstated monitoring recommendations for the potential risk of hepatotoxicity and pancreatitis distracts from a much more common and severe risk of fetal harm. Clinicians must be diligent about discussing this risk with patients and documenting when this discussion occurs. Changes to the current recommendations for monitoring of the boxed warnings associated with valproate therapy should be considered, such as more stringent monitoring requirements for the inherent fetal risk. This could be accomplished through a Risk Evaluation and Mitigation Strategy program or through institution-based policies and procedures. In addition, monitoring recommendations for the risk of hepatotoxicity and pancreatitis should account for contributing risk factors.

Is the Medicines and Healthcare products Regulator Agency (MHRA) guidance on sodium valproate acceptable to women of childbearing age?

BACKGROUND

The UK Medicines and Healthcare products Regulatory Agency (MHRA) published guidelines restricting the use of sodium valproate in women of childbearing age unless they consented to the pregnancy prevention programme (PPP), receiving counselling by an epilepsy specialist, or meeting exclusion criteria.

METHODS

We contacted every woman of childbearing age on valproate for epilepsy in NHS Tayside (122).

RESULTS

Seventeen out of 122 (13.9%) responded to the initial invitation to attend, and 25 out of 122 (20.4%) responded to a letter sent to their GP. Twenty-five attended, 21 completed a consent form, seven switched to another drug and three attended to express dissatisfaction with the MHRA guidance. There were 53 patients identified with learning difficulties. Consent was only taken from three patients, with carers declining to sign consent because the patient was not sexually active.

CONCLUSION

Our study suggests that patients and carers do not wish to stop valproate or engage in PPP despite being made aware of MHRA guidance.

The anti-epileptic drug valproic acid causes malformations in the developing craniofacial skeleton of zebrafish larvae

Valproic acid (VPA) is an anti-epileptic drug known to cause congenital craniofacial abnormalities, including orofacial clefts (OFC). The exact mechanisms by which VPA leads to craniofacial skeletal malformations are poorly understood. In this study, we investigated the effects of VPA on cartilage and bone formation in the zebrafish larval head during 1-13 hpf (early) and 25-37 hpf (late) development in which cranial neural crest cells (CNCCs) arise and then proliferate and differentiate, respectively. Double-staining for cartilage and bone at 5 dpf revealed that VPA reduced cartilage and bone formation in a dose-dependent manner after both early or late exposure. Several different CNCC-derived cartilage and bone elements were affected in both groups. In the early group (100 μM VPA), the posterior head length and the ethmoid plate were reduced in length (both p < 0.01), while mineralization of 4 out of 9 bone elements was often lacking (all p < 0.01). In the late group (100 μM VPA), also the posterior head length was reduced as well as the length of the ceratohyals (both p < 0.01). Similar to early exposure, mineralization of 3 out of 9 bone elements was often lacking (all p < 0.01). These results indicate that both CNCC formation (early) and differentiation (late) are hampered by VPA treatment, of which the consequences for bone and cartilage formation are persistent at 5 dpf. Indeed, we also found that the expression of several genes related to cartilage and bone was upregulated at 5 dpf. These data indicate a compensatory reaction to the lack of cartilage and bone. Altogether, VPA seems to induce craniofacial malformations via disturbed CNCC function leading to defects in cartilage and bone formation.

Are Women of Childbearing Age Still Receiving Valproate?

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

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

Valproic acid monotherapy in pregnancy and major congenital malformations

BACKGROUND

The use of valproic acid in the first trimester of pregnancy is associated with an increased risk of spina bifida, but data on the risks of other congenital malformations are limited.

METHODS

We first combined data from eight published cohort studies (1565 pregnancies in which the women were exposed to valproic acid, among which 118 major malformations were observed) and identified 14 malformations that were significantly more common among the offspring of women who had received valproic acid during the first trimester. We then assessed the associations between use of valproic acid during the first trimester and these 14 malformations by performing a case-control study with the use of the European Surveillance of Congenital Anomalies (EUROCAT) antiepileptic-study database, which is derived from population-based congenital-anomaly registries. Registrations (i.e., pregnancy outcomes with malformations included in EUROCAT) with any of these 14 malformations were compared with two control groups, one consisting of infants with malformations not previously linked to valproic acid use (control group 1), and one consisting of infants with chromosomal abnormalities (control group 2). The data set included 98,075 live births, stillbirths, or terminations with malformations among 3.8 million births in 14 European countries from 1995 through 2005.

RESULTS

Exposure to valproic acid monotherapy was recorded for a total of 180 registrations, with 122 registrations in the case group, 45 in control group 1, and 13 in control group 2. As compared with no use of an antiepileptic drug during the first trimester (control group 1), use of valproic acid monotherapy was associated with significantly increased risks for 6 of the 14 malformations under consideration; the adjusted odds ratios were as follows: spina bifida, 12.7 (95% confidence interval [CI], 7.7 to 20.7); atrial septal defect, 2.5 (95% CI, 1.4 to 4.4); cleft palate, 5.2 (95% CI, 2.8 to 9.9); hypospadias, 4.8 (95% CI, 2.9 to 8.1); polydactyly, 2.2 (95% CI, 1.0 to 4.5); and craniosynostosis, 6.8 (95% CI, 1.8 to 18.8). Results for exposure to valproic acid were similar to results for exposure to other antiepileptic drugs.

CONCLUSIONS

The use of valproic acid monotherapy in the first trimester was associated with significantly increased risks of several congenital malformations, as compared with no use of antiepileptic drugs or with use of other antiepileptic drugs.

Drug treatment of epilepsy in the century of the ILAE: the second 50 years, 1959-2009

The drug therapy of epilepsy evolved enormously in this 50 year period. Advances in therapeutics included the incorporation of pharmacokinetics into clinical practice, enormous advances in neurochemistry, a trend to antiepileptic drug monotherapy, better drug assessment, better understanding of therapeutic outcomes, and the recognition of the large epilepsy treatment gap in many countries. An unprecedented range of new drugs was introduced in this period. Before 1989, these included carbamazepine, valproate, ethosuximide, and the benzodiazepines. Since 1989, 13 more new drugs have been licensed and marketed and there are others in the pipeline. The International League Against Epilepsy and its leading figures have played an important role in these developments. In this period, too, there has been a rapid expansion in research and development within the pharmaceutical industry and a rise in the value of the antiepileptic drug market. In parallel, governmental regulation of pharmaceuticals has greatly increased. To what extent the overall prognosis of epilepsy has improved as a result of these activities is an interesting and perplexing question.

Refinement of 2q and 7p loci in a large multiplex NTD family

BACKGROUND

NTDs are considered complex disorders that arise from an interaction between genetic and environmental factors. NTD family 8776 is a large multigenerational Caucasian family that provides a unique resource for the genetic analysis of NTDs. Previous linkage analysis using a genome-wide SNP screen in family 8776 with multipoint nonparametric mapping methods identified maximum LOD* scores of approximately 3.0 mapping to 2q33.1-q35 and 7p21.1-pter.

METHODS

We ascertained an additional nuclear branch of 8776 and conducted additional linkage analysis, fine mapping, and haplotyping. Expression data from lymphoblast cell lines were used to prioritize candidate genes within the minimum candidate intervals. Genomic copy number changes were evaluated using BAC tiling arrays and subtelomeric fluorescent in situ hybridization probes.

RESULTS

Increased evidence for linkage was observed with LOD* scores of approximately 3.3 for both regions. Haplotype analyses narrowed the minimum candidate intervals to a 20.3 Mb region in 2q33.1-q35 between markers rs1050347 and D2S434, and an 8.3 Mb region in 7p21.1-21.3 between a novel marker 7M0547 and rs28177. Within these candidate regions, 16 genes were screened for mutations; however, no obvious causative NTD mutation was identified. Evaluation of chromosomal aberrations using comparative genomic hybridization arrays, subtelomeric fluorescent in situ hybridization, and copy number variant detection techniques within the 2q and 7p regions did not detect any chromosomal abnormalities.

CONCLUSIONS

This large NTD family has identified two genomic regions that may harbor NTD susceptibility genes. Ascertainment of another branch of family 8776 and additional fine mapping permitted a 9.1 Mb reduction of the NTD candidate interval on chromosome 7 and 37.3 Mb on chromosome 2 from previously published data. Identification of one or more NTD susceptibility genes in this family could provide insight into genes that may affect other NTD families.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

INTRODUCTION

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

METHODS

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

RESULTS

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

DISCUSSION

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

High-density single nucleotide polymorphism screen in a large multiplex neural tube defect family refines linkage to loci at 7p21.1-pter and 2q33.1-q35

BACKGROUND

Neural tube defects (NTDs) are considered complex, with both genetic and environmental factors implicated. To date, no major causative genes have been identified in humans despite several investigations. The first genomewide screen in NTDs demonstrated evidence of linkage to chromosomes 7 and 10. This screen included 44 multiplex families and consisted of 402 microsatellite markers spaced approximately 10 cM apart. Further investigation of the genomic screen data identified a single large multiplex family, pedigree 8776, as primarily driving the linkage results on chromosome 7.

METHODS

To investigate this family more thoroughly, a high-density single nucleotide polymorphism (SNP) screen was performed. Two-point and multipoint linkage analyses were performed using both parametric and nonparametric methods.

RESULTS

For both the microsatellite and SNP markers, linkage analysis suggested the involvement of a locus or loci proximal to the telomeric regions of chromosomes 2q and 7p, with both regions generating a LOD* score of 3.0 using a nonparametric identity by descent relative sharing method.

CONCLUSIONS

The regions with the strongest evidence for linkage map proximal to the telomeres on these two chromosomes. In addition to mutations and/or variants in a major gene, these loci may harbor a microdeletion and/or translocation; potentially, polygenic factors may also be involved. This single family may be promising for narrowing the search for NTD susceptibility genes.

An evaluation of maternal illnesses in the origin of neural-tube defects

OBJECTIVE

The objective of the study was to estimate risk of acute and chronic maternal diseases during pregnancy in the origin of neural-tube defects.

MATERIALS AND METHODS

Mothers with neural-tube defect fetuses/newborns (the NTD group), controls without any congenital defects (the normal control group) and controls with other defects (the other CA control group) were compared in the population-based data set of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1996. Of 1,202 cases with neural tube defects, 559 (49.8%) and 229 (19.1%) had mothers with one or more acute and chronic diseases, respectively. Of 38,151 mothers in the normal control group 14,004 (36.7%) and 8,328 (21.8%) had mothers with one or more acute or chronic diseases, respectively. Of 22,475 mothers in the other CA control group, 8,999 (40.0%) and 3,793 (16.9%) were affected with one or more acute or chronic maternal diseases, respectively. The prevalence of these diseases was evaluated in the 2nd months of gestation, however, if diseases occurred in the 1st month and continued in the 2nd month were also included.

RESULTS

There was a potential recall bias between the NTD group and the normal control group, but not between the NTD group and the other CA control group.

CONCLUSIONS

We suggest that maternal fever is a possible cause of neural-tube defects. Thus, these fevers should be treated with antipyretics during pregnancy. Among chronic maternal diseases, the possible association of migraine-headache, on the one hand and neural tube defects (particularly anencephaly) on the other hand cannot be excluded.

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

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

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.

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.

Malformations, withdrawal manifestations, and hypoglycaemia after exposure to valproate in utero

An unselected series is presented of 17 infants born to epileptic mothers and exposed to sodium valproate during pregnancy. Nine infants had minor abnormalities and of these infants five also had major malformations, described as the 'fetal valproate syndrome'. The most frequent malformation was congenital heart disease. Nine of the infants had manifestations of withdrawal, such as irritability, jitteriness, abnormalities of tone, seizures, and feeding problems. Four of these infants had an unrelated hypoglycaemia. The frequency of withdrawal symptoms was significantly related to the dose of valproate given to the mothers in the third trimester, and there was a tendency for both the frequency of the minor abnormalities and the major malformations to be related to the valproate dosage in the first trimester.

Single-dose tolerance and pharmacokinetics of 2-n-propyl-2(E)-pentenoate (delta 2(E)-valproate) in healthy male volunteers

2-n-Propyl-2(E)-pentenoic acid (delta 2(E)-valproate) was administered to healthy volunteers in oral doses of 50-800 mg. The drug was tolerated well and no significant adverse effects were observed. Pharmacokinetic parameters were determined. Valproate and 3-keto-valproate were detected as metabolites.

Developmental toxicity of valproic acid

Valproic acid is a very effective anticonvulsant agent widely used in the management of various forms of epilepsy. Administration of the drug during pregnancy results in increased incidence of congenital abnormalities in both humans and experimental animals. In recent years, a significant number of research efforts have attempted to define the contributory role of valproic acid to the impairment of normal prenatal growth and development. The present report summarizes current knowledge that has emerged from clinical and research studies. The specific topics include: the placental transfer of valproic acid; the teratogenic potential; structure-teratogenicity and dose-response relationships; species and strain differences; biochemical changes evoked by the drug in the fetus.

Teratogenic effects on the neuroepithelium of the CD-1 mouse embryo exposed in utero to sodium valproate

A causal association has now been recognized between the use of the anticonvulsant drug sodium valproate during pregnancy and the increased incidence of spina bifida in the human population. The objective of this study was to investigate the teratogenic effects of sodium valproate on the cephalic 1) neuroepithelium, 2) extracellular matrix, and 3) embryonic protein content in the CD-1 mouse embryo. Nulliparous female CD-1 mice were dosed intraperitoneally on day 8 of gestation with 340 mg/kg of sodium valproate. On day 10 of gestation, females were killed by cervical dislocation, and all live embryos were assigned to one of the following groups and processed accordingly for: 1) head measurements, 2) scanning electron microscopy, 3) total protein determination, 4) two-dimensional polyacrylamide gel electrophoresis, 5) immunohistochemistry, and 6) light microscopy. Exposure to sodium valproate at the selected dosage resulted in a 30% incidence of neural tube defects in the cranial region of these embryos. Treated embryos showed a significant reduction in head size, indicating a drug-induced microcephaly. No major differences were seen in the total embryonic protein patterns between control and treated embryos. Immunoreactivity to laminin and fibronectin showed a similar distribution in control and treated embryos except in the vasculature pattern of the hindbrain neuroepithelium. The neuroepithelium of the treated embryos showed marked disorganization when it was examined histologically, particularly in the forebrain region. Cells were disoriented, and there was a noticeable loss of intercellular adhesion in the juxtaluminal region. Increased cellular blebbing was apparent at the ependymal surface, and large protrusions of cells were seen invading the neural tube lumen. The lumen was distorted in shape and frequently contained blood cells. Irregularities and gaps were observed in the underlying basal lamina. These results suggest that treatment with sodium valproate during a critical time in neurogenesis in the CD-1 mouse embryo alters the normal architecture of the neuroepithelium, with a loss of integrity at both the basal and apical surfaces. The alterations seen in the neuroepithelium at any of these sites in this animal model could help explain the increased incidence of spina bifida seen in children of epileptic mothers receiving sodium valproate.

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.

Three cases of delivery under sodium valproate--placental transfer, milk transfer and probable teratogenicity of sodium valproate

Here is a report of three cases of delivery from women who have taken sodium valproate (VPA). One neonate was born with polydactylism, and we reviewed the congenital malformations in children of mothers who have taken VPA. In the other two cases, we also examined the levels of VPA in the cord serum and breast milk. The levels of VPA in the cord serum were 50 micrograms/ml at 12 hours after the last maternal dose and 75 micrograms/ml at 14 hours after the last maternal dose. The blood levels of VPA in the two mothers were 48-59 micrograms/ml and 55-85 micrograms/ml in their late pregnancy, respectively. The levels of VPA in the breast milk were 2.0-3.5 micrograms/ml and the ratio of VPA in the breast milk to blood was 2-3%. These results suggest the high rate of placental transfer and the low rate of milk transfer of VPA.

Verification of the fetal valproate syndrome phenotype

We have evaluated 19 children who were exposed to valproic acid (VPA) in utero to look for manifestations of a fetal valproate syndrome (FVS), as proposed by Di Liberti et al. [1984]. We found no consistent alterations of pre- or postnatal growth with exposure to VPA monotherapy. Postnatal growth deficiency and microcephaly were present however, in two thirds of children exposed to VPA in combination with other anticonvulsants. Developmental delay or neurologic abnormality was found in 71% of those exposed to VPA monotherapy, and in 90% of those exposed to VPA and other anticonvulsants. Craniofacial anomalies, which can be seen with other anticonvulsant exposures, including midface hypoplasia, short nose with a broad and/or flat bridge, epicanthal folds, minor abnormalities of the ear, philtrum or lip, and micrognathia were also found in infants whose mothers used VPA. Prominent metopic ridge and outer orbital ridge deficiency or bifrontal narrowing and certain major anomalies such as tracheomalacia, talipes equinovarus (with intact spine) and lumbosacral meningomyelocele seem to be peculiar to infants with VPA exposure. Other defects such as urogenital anomalies, inguinal or umbilical hernias, and minor digital anomalies that are common to other prenatal anticonvulsant exposures are also occasionally found in those exposed to VPA. Heart defects have been found in infants exposed to nearly every class of anticonvulsant although the types of defects associated with maternal VPA use may be clarified when classified by pathogenetic mechanism. Our findings overall are in agreement with the report of Di Liberti et al. [1984].

Fetal valproate syndrome: is there a recognisable phenotype?

Four infants who were exposed to sodium valproate or valproic acid during pregnancy are described. Common facial features in the three surviving infants include epicanthic folds, a flat nasal bridge, a broad nasal base, anteverted nostrils, a shallow philtrum, and a thin upper lip with a thick lower lip. Ridging of the metopic suture, congenital heart defect, postaxial polydactyly, and hypospadias were additional features in individual cases. In agreement with previous authors, we feel that there is a distinctive 'fetal valproate' phenotype.

Teratogen update: valproic acid

Valproic acid use during pregnancy results in an absolute risk for spina bifida of 1-2%. This increased risk is comparable to the recurrence risk for neural tube defects and warrants informed counselling and access to prenatal diagnosis. There is no substantial evidence that valproic acid use increases the risk for other specific major malformations above the increased risk due to maternal epilepsy. Valproic acid may cause a characteristic pattern of minor facial malformations. Further definition and confirmation are required, and the magnitude of the risk needs to be determined. There are inadequate data to assess the magnitude, if any, of the risks for postnatal growth abnormalities and developmental disabilities associated with the use of valproic acid during pregnancy. Birth-defect monitoring programs and international collaboration among the staffs of monitoring programs played a major role in determining that valproic acid is a human teratogen.

Studies in neural tube defects. I. Epidemiologic and etiologic aspects

In the NIH Collaborative Perinatal Project, a prospective study of over 53,000 pregnant women and their offspring, 71 single-born children (13.33/10,000) were found to have a non-syndromal neural tube defect (NTD). A family history was present in only one case. The group of individuals with NTD was compared to a group of 400 randomly selected non-malformed control infants. Of over 50 maternal factors studied the following showed significant association with NTD in the offspring: diabetes mellitus; organic heart disease; lung disease; and diuretic, antihistamine, and sulfonamide use. The interval between the termination of the immediately previous pregnancy and the start of the proband pregnancy was significantly shorter in mothers of NTD children than in mothers of control infants. The risk for NTD was also significantly increased if the immediately previous pregnancy was a spontaneous abortion. There was no increased risk for NTDs among sibs of children with major malformations such as tracheo-esophageal "dysraphism," cleft lip/palate, or renal agenesis. NTDs are apparently etiologically heterogeneous.

Maternal toxicity of drugs and metabolic disorders--a possible etiologic factor in the intrauterine death and congenital malformation: a critique on human data

Human data were searched to determine whether an association of metabolically or drug-induced maternal toxicity with congenital malformations and intrauterine death would be valid for the human species. Intrauterine death was found to occur in association with maternal homeostatic alterations resulting from phenylketonuria and diabetes, and with maternal toxicity from toxemia of pregnancy, leukemia, burns, alcohol, aminopterin, isotretinoin, and possibly trimethadione. A pattern of anomalies found similar (except for minor differences) and thus suggestive of a possible common cause, was observed among anomalies to phenylketonuria, diabetes mellitus, aminopterin, alcohol, warfarin, phenytoin, phenobarbital, trimethadione, valproic acid, and isotretinoin. The pattern usually consisted of deficiencies in pre- and postnatal development, mid-facial hypoplasia, cleft palate, atrial or ventricular septal defects, patent ductus arteriosus, hypospadias, hernias, and other less frequent anomalies. The pattern is tentatively associated with alterations in maternal physiology resulting from phenylketonuria and diabetes; maternal toxicity of aminopterin, alcohol, and diverse factors co-occurring with warfarin use; and therapeutic doses (generally toxic in adults) of phenytoin, phenobarbital, trimethadione, and valproic acid. Whether these fetal malformations and intrauterine deaths would occur at nonmaterno-toxic levels of the above teratogenic agents, and, consequently, the strength of the associations could not be estimated for lack of data. However, human data seem to provide some, though weak, support and not to contradict the previous assumption formulated from animal studies that maternal toxicity may be causally related to fetal malformations and embryo-fetal mortality.

Fetal growth, major malformations, and minor anomalies in infants born to women receiving valproic acid

The association of fetal and neonatal distress, birth measurements, major malformations, and minor anomalies was studied prospectively in 14 infants of women with epilepsy who were receiving valproic acid (VPA) monotherapy and in 12 infants of women with epilepsy who were receiving VPA in combination with other anticonvulsant drugs. Comparison was made with 26 matched-pair controls and 116 controls from a larger study of antiepileptic drugs. During the first trimester, total VPA serum concentrations were well above therapeutic levels (100 to 184 micrograms/ml) in two women receiving high VPA doses (2000 and 1500 mg daily). Although dosage remained the same, serum concentrations decreased during pregnancy to therapeutic levels (33.9 to 57.0 micrograms/ml). The VPA percent free fraction increased in the third trimester and was threefold higher at birth. Almost half of the infants exposed to VPA monotherapy were distressed during labor, and 28% had low Apgar scores. Fetal and neonatal distress may be caused by the high VPA percent free fraction during labor and at birth. Mean body measurements at birth after VPA monotherapy were comparable to those in the matched control group, but were reduced in the group of infants receiving VPA combination therapy. Four infants exposed to VPA monotherapy were born with major malformations. The median number of minor anomalies was four times higher in infants whose mothers received VPA alone or VPA combination therapy than in controls. Seven infants had a pattern of craniofacial and digital anomalies that was distinctly different from that observed after in utero exposure to other anticonvulsant medications. The occurrence of major malformations and the number of minor anomalies may be dose related.

Prenatal antiepileptic drug exposure alters seizure susceptibility in rats

An animal model is used to address the issue of prenatal exposure to certain antiepileptic drugs and seizure susceptibility in the offspring. Administration of doses established as median therapeutic doses in humans of phenobarbital, valproate and clonazepam to pregnant rats during the last third of gestation produced sexually dimorphic alterations in pentylenetetrazol (PTZ)-induced seizures as well as in non-convulsive (spontaneous alternation and cliff avoidance) behaviors in the offspring. Altered seizure susceptibility occurred in the absence of overtly recognizable morphological abnormalities and did not appear to reflect differences in the status of circulating drug-binding plasma proteins. Possible neural and/or metabolic mechanisms responsible for these behavioral changes are discussed.

Predicting the human teratogenic potential of the anticonvulsant, valproic acid, from a non-human primate model

The anticonvulsant, valproic acid (VPA) is a suspected human teratogen. This study, employing the rhesus monkey as an animal model, demonstrates that VPA has a significant teratogenic potential in the monkey. Timed pregnant monkeys were exposed orally to VPA at approx. 1X, 10X, and 30X (20, 200, and 600 mg/kg/day, respectively) the human therapeutic dose, daily, during organogenesis (gestation days 21-50). All fetuses of mothers exposed to greater than 1X exhibited some form of embryotoxicity. The highest dose, 30X, was 100% embryolethal, while offspring of the 10X dose group exhibited craniofacial and skeletal defects, and low body weights. Maternal pharmacokinetic parameters and plasma metabolites were determined for VPA on the first and last day of dosing for the 10X dose group. Comparison of the kinetic and metabolite data with that obtained for man indicates that the rhesus monkey is a good model for predicting the teratogenic potential of VPA in the human.

An update on sodium valproate

Sodium valproate has been in clinical use for the treatment of epilepsy in Great Britain since 1973 and in the United States since 1978. It is chemically quite different from the existing antiepileptic drugs. Although most authorities concentrate on its modification of GABAergic inhibitory transmission in the central nervous system, its mechanism of action remains obscure. It has been shown to be an effective antiepileptic drug in a wide variety of seizure types, but clinically, its major use to date has been in generalized seizures. It is particularly effective in photosensitive epilepsy and myoclonus. Most adverse reactions to sodium valproate are mild and reversible, but with increasing experience, the drug's rare, idiosyncratic, adverse effects are becoming apparent, particularly hepatotoxicity and teratogenicity. The role of therapeutic drug monitoring in the management of patients taking sodium valproate is controversial.

Maternal serum alpha-fetoprotein screening for neural tube defects. Report of a combined study in Germany and short overview on screening in populations with low birth prevalence of neural tube defects

The basis of maternal serum alpha-fetoprotein (AFP)-screening for neural tube defects is discussed. A report is given of a large scale screening study in the Federal Republic of Germany combining the experiences in Giessen and Hannover on over 50,000 pregnant women, about evenly distributed among both centers. Published and known forthcoming data from other low incidence populations, particularly of European countries, are reviewed briefly. The conclusion is reached that general screening could effectively be instituted and in the final result should also be cost-beneficial.

The fetal valproate syndrome

We evaluated seven children who had been exposed to sodium valproate (or valproic acid) in utero. A consistent facial phenotype was observed in all seven in addition to other birth defects in four. The facial changes consisted of epicanthal folds which continued inferiorly and laterally to form a crease or groove just under the orbit, flat nasal bridge, small upturned nose, long upper lip with a relatively shallow philtrum, a thin upper vermillion border, and downturned angles of the mouth. Hypospadias, strabismus, and psychomotor delay were found in two males; two children had nystagmus and two had low birth weight.