Teratogenic effects of antiepileptic drugs

Impact of maternal topiramate ingestion on ossification of skull and appendicular bones in rat fetuses

The skull and appendicular bones are derived from different embryological sources during their development. The impact of prenatal exposure of topiramate on ossification of these bones is not adequately studied. The goal of this study was to assess the ossification patterns of the craniofacial bones and bones of the forelimbs and hindlimbs in 20-day-old rat fetuses after maternal exposure to topiramate at doses equivalent to human therapeutic doses. Three groups of Sprague-Dawley pregnant rats were used: control, topiramate 50mg/kg/day (T50) and topiramate 100mg/kg/day (T100). Topiramate was given by oral gavage from day 6 to day19 of gestation. Ossification was evaluated in the bones of 20 days fetuses after staining with Alizarin red. Results showed a significant reduction in complete ossified centers of the metacarpal, metatarsal and craniofacial bones in topiramate-exposed fetuses at both doses when compared to the control group. Also, a significant decrease in the length of ossified part of the long bones of the forelimbs and hindlimbs in topiramate-exposed fetuses at both doses was noted when compared to the control group. Crown-rump length and fetal weight were significantly decreased in topiramate treated groups compared to the control group. In all examined groups, there was a positive correlation between the crown-rump length and the lengths of humerus and femur. No abnormalities in the ossified bones and no significant changes in their ossification pattern were observed between the treated groups. In conclusion, prenatal administration of topiramate in doses equivalent to human therapeutic doses delayed ossification and development of craniofacial and appendicular bones in rat fetuses and their effects are not dose dependent at doses investigated. The implications of these findings in women who require topiramate therapy in pregnancy merit further evaluation.

Development of Antiepileptic Drugs throughout History: From Serendipity to Artificial Intelligence

This article provides a comprehensive narrative review of the history of antiepileptic drugs (AEDs) and their development over time. Firstly, it explores the significant role of serendipity in the discovery of essential AEDs that continue to be used today, such as phenobarbital and valproic acid. Subsequently, it delves into the historical progression of crucial preclinical models employed in the development of novel AEDs, including the maximal electroshock stimulation test, pentylenetetrazol-induced test, kindling models, and other animal models. Moving forward, a concise overview of the clinical advancement of major AEDs is provided, highlighting the initial milestones and the subsequent refinement of this process in recent decades, in line with the emergence of evidence-based medicine and the implementation of increasingly rigorous controlled clinical trials. Lastly, the article explores the contributions of artificial intelligence, while also offering recommendations and discussing future perspectives for the development of new AEDs.

Effects of GABAB receptor positive allosteric modulator BHF177 and IRS-1 on apoptosis of hippocampal neurons in rats with refractory epilepsy via the PI3K/Akt pathway

The present study was conducted to determine the effects of the γ-aminobutyric acid B (GABA_B ) receptor positive allosteric modulator BHF177 on refractory epilepsy (RE). An RE rat model was initially established via treatment with lithium-pilocarpine. The RE rats were then treated with BHF177 or the GABA_B receptor antagonist CGP46381, followed by recording of their seizure rate and assessment of their spatial learning in the Morris water maze test. Treatment of BHF177 reduced the seizure intensity, whereas this effect was revered upoj treatment with CGP46381. Immunohistochemistry revealed that BHF177 treatment diminished P-glycoprotein (P-gp) expression in the hippocampal tissues of RE rats. Next, we found that BHF177 activated GABA_B receptor, resulting in upregulated expression of insulin receptor substrate 1 (IRS-1) and PI3K, as well as antiapoptotic factors (Bcl-2 and mTOR), along with suppression of the apoptosis factors Bax and cleaved caspase-3 in the hippocampal tissues. Further, activation of GABA_B receptors by BHF177 alleviated the inflammatory response in hippocampal tissues of RE rats, as evidenced by reduced VCAM-1, ICAM-1, and tumor necrosis factor-α levels. Next, we treated primary cultured rat hippocampal neurons with BHF177 and the IRS-1 selective inhibitor NT157. BHF177 inhibited hippocampal apoptosis in rat hippocampal neurons by regulating the IRS-1/PI3K/Akt axis through crosstalk between GABA_B and insulin-like growth factor-1 receptors. Collectively, our findings indicate that the BHF177 inhibited neuron apoptosis, thus protecting against RE through the IRS-1/PI3K/Akt axis, which may present a new therapeutic channel for RE.

The Effect of Metformin in Experimentally Induced Animal Models of Epileptic Seizure

Background

Epilepsy is one of the common neurological illnesses which affects millions of individuals globally. Although the majority of epileptic patients have a good response for the currently available antiepileptic drugs (AEDs), about 30-40% of epileptic patients are developing resistance. In addition to low safety profiles of most of existing AEDs, there is no AED available for curative or disease-modifying actions for epilepsy so far.

Objectives

This systematic review is intended to evaluate the effect of metformin in acute and chronic animal models of an epileptic seizure.

Methods

We searched PubMed, SCOPUS, Sciences Direct, and grey literature in order to explore articles published in English from January 2010 to November 2018, using key terms “epilepsy,” “seizure,” “metformin,” “oral hypoglycemic agents,” and “oral antidiabetic drugs”. The qualities of all the included articles were assessed according to the Collaborative Approach to Meta-Analysis and Review of Animal Data from Experimental Studies (CAMARADES).

Results

Out of six hundred fifty original articles retrieved, eleven of them fulfilled the inclusion criteria and were included for final qualitative analysis. In these studies, metformin showed to control seizure attacks by attenuating seizure generation, delaying the onset of epilepsy, reducing hippocampal neuronal loss, and averting cognitive impairments in both acute and chronic models of an epileptic seizure. The possible mechanisms for its antiseizure or antiepileptic action might be due to activation of AMPK, antiapoptotic, antineuroinflammatory, and antioxidant properties, which possibly modify disease progression through affecting epileptogenesis.

Conclusion

This review revealed the benefits of metformin in alleviating symptoms of epileptic seizure and modifying different cellular and molecular changes that affect the natural history of the disease in addition to its good safety profile.

Carbamazepine adverse drug reactions

INTRODUCTION

Carbamazepine (CBZ) is used for the treatment of epilepsy and other neurological and psychiatric disorders. The occurrence of adverse reactions (ADRs) to CBZ can negatively impact the quality of life of patients, as well as increase health-care costs. Thus, knowledge of CBZ-induced ADRs is important to achieve safer treatment outcomes. Areas covered: This review describes the clinical features, known mechanisms, and clinical management of the main CBZ-induced ADRs. In addition, pharmacogenetic studies focused on ADRs induced by CBZ are cited. Expert commentary: CBZ-induced ADRs are well known in the literature. The metabolite CBZ-10,11-epoxide plays an important role in the mechanism that underlies the ADRs induced by CBZ. Several factors should be considered for a safer use of CBZ, such as monotherapy prescription when possible, an adequate dose titration, knowledge of previous ADRs in the patient, and routine monitoring of CBZ plasma concentrations in symptomatic patients. Pharmacogenetics is a potential tool for CBZ therapy improvement, and the design of multicenter studies focused on the identification of biomarkers for CBZ-induced ADRs could provide useful information for a safer CBZ therapy.

Impairment of heart rhythm complexity in patients with drug-resistant epilepsy: An assessment with multiscale entropy analysis

OBJECTIVE

Epilepsy and seizures can have dramatic effects on the cardiac function. The aim of this study was to investigate the heart rhythm complexity in patients with drug-resistant epilepsy (DRE).

METHODS

Ambulatory 24-h electrocardiograms (ECG) from 70 DRE patients and 50 healthy control subjects were analyzed using conventional heart rate variability (HRV) and multiscale entropy (MSE) methods The variation of complexity indices (CI), which was calculated from MSE profile, was determined.

RESULTS

DRE patients had significantly lower time domain (Mean RR, SDNN, RMSSD, pNN50) and frequency domain (VLF, LF, HF, TP) HRV measurements than healthy controls. Of the MSE analysis, MSE profile, CI including Slope 5, Area 1-5, Area 6-15 and Area 6-20 were significantly lower than those in the healthy control group. In receiver operating characteristic (ROC) curve analysis, VLF had the greatest discriminatory power for the two groups. In both net reclassification improvement (NRI) model and integrated discrimination improvement (IDI) models, CI derived from MSE profiles significantly improved the discriminatory power of Mean RR, SDNN, RMSSD, pNN50, VLF, LF, HF and TP.

SIGNIFICANCE

The heart rate complexity is impaired for DRE patients. CI are useful to discriminate DRE patients from subjects with normal cardiac complexity. These findings indicate that MSE method may serve as a complementary approach for characterizing and understanding abnormal heart rate dynamics in epilepsy. Furthermore, the CI may potentially be used as a biomarker in monitoring epilepsy.

Valproic acid protects against haemorrhagic shock-induced signalling changes via PPARγ activation in an in vitro model

BACKGROUND AND PURPOSE

Valproic acid (VPA), a widely used epilepsy and bipolar disorder treatment, provides acute protection against haemorrhagic shock-induced mortality in a range of in vivo models through an unknown mechanism. In the liver, this effect occurs with a concomitant protection against a decrease in GSK3β-Ser(9) phosphorylation. Here, we developed an in vitro model to investigate this protective effect of VPA and define a molecular mechanism.

EXPERIMENTAL APPROACH

The human hepatocarcinoma cell line (Huh7) was exposed to conditions occurring during haemorrhagic shock (hypoxia, hypercapnia and hypothermia) to investigate the changes in GSK3β-Ser(9) phosphorylation for a 4 h period following treatment with VPA, related congeners, PPAR agonists, antagonists and siRNA.

KEY RESULTS

Huh7 cells undergoing combined hypoxia, hypercapnia, and hypothermia reproduced the reduced GSK3β-Ser(9) phosphorylation shown in vivo during haemorrhagic shock, and this change was blocked by VPA. The protective effect occurred through upstream PTEN and Akt signalling, and prevented downstream β-catenin degradation while increasing histone 2/3 acetylation. This effect was reproduced by several VPA-related compounds with known PPARγ agonist activity, independent of histone deacetylase (HDAC) inhibitory activity. Specific pharmacological inhibition (by T0070907) or knockdown of PPARγ blocked the protective effect of VPA against these signalling changes and apoptosis. In addition, specific activation of PPARγ using ciglitazone reproduced the changes induced by VPA in haemorrhagic shock-like conditions.

CONCLUSION AND IMPLICATIONS

Changes in GSK3β-Ser(9) phosphorylation in in vivo haemorrhagic shock models can be modelled in vitro, and this has identified a role for PPARγ activation in the protective role of VPA.

Reduction in mortality and teratogenicity following simultaneous administration of folic acid and vitamin E with antiepileptic, antihypertensive and anti-allergic drugs

Aim:

The present study was designed to evaluate the teratogenic effects on breeding pattern in mice following administration of lamotrigine (LT) and levetiracetam (LV) and its combination with anti-hypertensive and anti-allergic drugs. Moreover, possibility of decrease in teratogenic effect was also evaluated upon simultaneous administration of these combinations with folic acid or vitamin E.

Materials and Methods:

The study was carried out on mature female mice housed in polycarbonate breeding cages. Drugs were administered continuously till the birth of neonates and pups were examined for any teratogenic potential of drugs.

Results:

The results of the study reveals that teratogenic effects of lamotrigine, methyldopa and loratadine (LTMLO) combination were seems to be reduced upon simultaneous administration with folic acid, while addition of vitamin E was found to be more effective in reducing the mortality rate of levetiracetam, methyldopa and loratadine combination.

Conclusion:

Teratogenic effects of LTMLO combination were better prevented by folic acid. However, further studies on large number of animals and humans are required before reaching to definite conclusion.

Teratogenic potential of antiepileptic drugs in the zebrafish model

The zebrafish model is an attractive candidate for screening of developmental toxicity during early drug development. Antiepileptic drugs (AEDs) arouse concern for the risk of teratogenicity, but the data are limited. In this study, we evaluated the teratogenic potential of seven AEDs (carbamazepine (CBZ), ethosuximide (ETX), valproic acid (VPN), lamotrigine (LMT), lacosamide (LCM), levetiracetam (LVT), and topiramate (TPM)) in the zebrafish model. Zebrafish embryos were exposed to AEDs from initiation of gastrula (5.25 hours post-fertilization (hpf)) to termination of hatching (72 hpf) which mimic the mammalian teratogenic experimental design. The lethality and teratogenic index (TI) of AEDs were determined and the TI values of each drug were compared with the US FDA human pregnancy categories. Zebrafish model was useful screening model for teratogenic potential of antiepilepsy drugs and was in concordance with in vivo mammalian data and human clinical data.

Preschool behavioral problems in children prenatally exposed to antiepileptic drugs - a follow-up study

We studied the association between maternal epilepsy, antiepileptic drug (AED) treatment, and behavioral problems in preschool children. In the Danish National Birth Cohort, we identified 4- to 5-year-old children whose mothers had epilepsy and received AED treatment (n=133) or not (n=304) during pregnancy and compared them with randomly selected children whose mothers did not have epilepsy (n=1193). The children's behavioral problems were assessed by the use of the Strengths and Difficulties Questionnaire (SDQ). Children prenatally exposed to AEDs more often had an abnormal total SDQ score as compared with children of women without epilepsy (odds ratio (OR)=4.8 (95% CI: 1.9-12.1)) and as compared with children of women with epilepsy who were not treated with AEDs during their pregnancy (OR=4.0 (95% CI: 1.3-12.8)). In conclusion, prenatal AED exposure may increase the risk of behavioral problems in preschool children even after adjustments for potential confounders and maternal epilepsy.

Neurobehavioral consequences of prenatal antiepileptic drug exposure

Despite elevated rates of birth defects associated with prenatal antiepileptic drug exposure, pharmacotherapy is typically continued throughout pregnancy because of the risks posed to mother and child by recurrent seizures. Emerging data suggest that prenatal exposure to valproate or polytherapy may also be associated with increased risk of cognitive impairment. However, our understanding of the longer-term sequelae of prenatal antiepileptic drug exposure remains incomplete. Improved understanding of the neurobehavioral consequences of prenatal antiepileptic drug exposure is essential to ensure accurate information is available for women with epilepsy planning a pregnancy, and to achieve optimal outcomes for mothers and children.

Synaptic and intrinsic balancing during postnatal development in rat pups exposed to valproic acid in utero

Valproic acid (VPA) is among the most teratogenic of commonly prescribed anticonvulsants, increasing the risk in humans of major malformations and impaired cognitive development. Likewise, rats exposed prenatally to VPA exhibit a variety of neuroanatomical and behavioral abnormalities. Previous work has shown that pyramidal neuron physiology in young VPA-exposed animals is marked by two strong abnormalities: an impairment in intrinsic neuronal excitability and an increase in NMDA synaptic currents. In this study, we investigated these abnormalities across postnatal development using whole-cell patch recordings from layer 2/3 neurons of medial prefrontal cortex. We found that both abnormalities were at a peak soon after birth but were gradually corrected as animals matured, to the extent that normal excitability and NMDA currents had been restored by early adolescence. The manner in which this correction happened suggested coordination between the two processes. Using computational models fitted to the physiological data, we argue that the two abnormalities trade off against each other, with the effects on network activity of the one balancing the effects of the other. This may constitute part of the nervous system's homeostatic response to teratogenic insult: an attempt to maintain stability despite a strong challenge.

Pharmacotherapeutics of epilepsy: use of lamotrigine and expectations for lamotrigine extended release

The goal in managing patients with epilepsy is complete seizure freedom. Pharmacotherapeutic management of epilepsy is complicated by multiple syndromes, inter-individual differences in drug sensitivities, inter-individual differences in drug disposition, and drug interactions. Most anti-epileptic drugs (AEDs) have a therapeutic window with only a 2- to 3-fold concentration range. Extended release formulations offer advantages over their immediate release counter parts with less fluctuation in the serum concentration vs time curve and improved compliance. However, missed doses are more likely to result in prolonged “sub-therapeutic serum concentrations”. Best clinical outcome may sometimes require twice daily dosing of extended release formulations even though approved for once daily dosing, as this optimally balances pharmacokinetics against compliance. Lamotrigine (LTG) is a broad spectrum AED with efficacy in partial and generalized epilepsy syndromes and good tolerability. Its metabolism is affected by co-medications which may be inducing, neutral or inhibiting of hepatic glucuronidation. Furthermore, though the average half-life in monotherapy is about 24 hours, there is a large inter-individual variation that may, including the extremes, approach a range of 10-fold. LTG-XR is expected to decrease fluctuation of serum concentration in the presence of hepatic inducing or neutral drugs. However, optimal clinical benefit in some patients may require twice daily dosing when metabolism is rapid.

The prevalence and management of epilepsy in secondary school pupils with and without special educational needs

OBJECTIVES

The objectives of this paper were to (i) determine the prevalence of epilepsy (including the various epilepsies and epilepsy syndromes) in a secondary school population; and (ii) compare the management of epilepsy between secondary school pupils with and without special educational needs.

METHODS

Retrospective observational study of a 250, 000 population (West Cheshire Health District). Pupils attending secondary school with epilepsy over a 1-year period were identified from the local Child Health Computer, school nurse and DGH records. Health records were examined to determine the prevalence, characteristics and management of the epilepsy, and the presence of any special educational needs, other learning difficulties or physical disability.

RESULTS

The prevalence of epilepsy was 4.1 per 1000, being 10 times higher among adolescents who had special educational needs. Pupils with epilepsy and special educational needs had more poorly controlled epilepsy, but did not have a higher number of focal seizures nor were they taking a greater number of anti-epileptic drugs. A physical disability occurred five times more often in those with special educational needs and epilepsy. While epilepsy in pupils at mainstream school without special educational needs was better controlled, one-fifth of these subjects had poorly controlled epilepsy and a few also had physical disabilities.

CONCLUSIONS

Epilepsy is more challenging to control in adolescents with special educational needs attending special schools. However, some pupils in mainstream secondary schools had poorly controlled epilepsy even when they did not have recognized special educational needs. Health and education professionals working across the range of secondary school environments need to be able to support pupils with challenging epilepsy, many of whom will also have special educational needs and some a physical disability, as an increasing number of adolescents with these difficulties are being placed in mainstream schools.

Development and implementation of an adolescent epilepsy transition clinic

This article describes the collaborative development of a nurse-led transition clinic within the Comprehensive Epilepsy Program at the Stollery Children's Hospital and at the University of Alberta Hospital. Developed in 2005, our program has been instrumental in assisting 97 teens and their parents' transition from pediatric to adult epilepsy care. Through our Adolescent Epilepsy Transition Clinic, we address concerns expressed by teens and their parents when shifting from pediatric to adult healthcare services, including fear of the unknown, change in appointment location, loss of established relationships, and anticipated decrease in the quality of care posttransition. We also address concerns of adult and pediatric healthcare providers related to the adolescents' working knowledge of how their particular type of epilepsy and its management interact with typical adolescent developmental challenges and future career and lifestyle choices. The results from a process evaluation are presented and offer new insights for improving adolescent transition.

Population-based study of antiepileptic drug exposure in utero--influence on head circumference in newborns

PURPOSE

To study the effect of AED exposure on head circumference in the newborn.

METHODS

Data on all Swedish singletons births between 1995 and 2005, over 900,000 births, were obtained from the Swedish Medical Birth Registry. The effects of AEDs on birth-weight-adjusted mean head circumference (bw-adj-HC) were estimated by comparison with data from all births in an analysis which was adjusted for year of birth, maternal age, parity, maternal smoking, and maternal body mass index.

RESULTS

A significant reduction of mean bw-adj-HC was seen after both carbamazepine (CBZ) (standard deviation scores (SDS)=0.15, p<0.001) and valproic acid (VPA) (SDS=0.10, p=0.04) in monotherapy. No effect on mean bw-adj-HC was seen for phenytoin, clonazepam, lamotrigine and gabapentin. There was a significant increase in the occurrence of microcephaly (bw-adj-HC smaller than 2 SD below the mean) after any AED polytherapy (OR=2.85, 95% CI: 1.74-4.78) but not after AED monotherapy or monotherapy with CBZ or VPA. CBZ or VPA was taken by 71% of the pregnant mothers on AED, and the usage increased over time.

CONCLUSIONS

CBZ and VPA in monotherapy during pregnancy reduce mean bw-adj-HC. AED polytherapy increases the rate of microcephaly but no significant effect is seen of AED monotherapy. The possible significance for the further development of the child is uncertain but should be explored.

Anticonvulsants in the treatment of major depressive disorder: an overview

Major depressive disorder (MDD) is highly prevalent, potentially disabling, and sometimes fatal. Antidepressants (ADs) have improved its treatment, but incomplete response, sustained morbidity, recurrences, agitation, substance abuse, excess medical mortality, and suicide remain unsolved problems among mood disorder patients. AD treatment itself sometimes induces adverse behavioral responses. Several anticonvulsants (ACs) used to treat bipolar disorder (BPD) might also be of value for MDD. Accordingly, we reviewed published reports on ACs for MDD, identifying studies by computerized searches. We excluded reports dealing only with BPD patients or with sedatives, classified trials by design quality, and evaluated treatment of acute episodes and recurrences of adult MDD. We found 36 reports involving 41 relevant trials of carbamazepine (12 trials), valproate (11), lamotrigine (9), gabapentin (3), topiramate (3), phenytoin (2), and tiagabine (1). They include 9 blinded, controlled trials (of 28-70 days), involving carbamazepine (3 trials), lamotrigine (3), phenytoin (2), or topiramate (1) as primary treatments (5) or AD adjuncts (4). Some of these trials, as well as 7 of lesser quality, suggest benefits of carbamazepine, lamotrigine, and valproate, mainly as adjuncts to ADs. Another 20 anecdotes or small trials further suggest that these ACs might be useful as AD adjuncts-specifically to treat irritability or agitation in MDD. Overall, these reports provide suggestive evidence of beneficial effects of carbamazepine, lamotrigine, and valproate that require further study, especially for long-term adjunctive use, particularly in patients with recurring MDD with prominent irritability or agitation.

Lamotrigine and twin pregnancy, incidental event or possible correlation?

Lamotrigine is frequently used to manage epilepsy during pregnancy. However, some major and minor birth defects are reported with lamotrigine monotherapy. This study is a case series report on 20 epileptic women who were receiving lamotrigine in their pregnancy. Apart from the normal pregnancies and births, in our study three patients gave birth to healthy twins, two vanished twin syndromes occurred and one patient had abortion. Twin pregnancy in association with lamotrigine therapy has not been clearly described before. Our observational study raises the idea that lamotrigine may induce twin pregnancy but larger studies need to investigate the presence or absence of such association more decently.

Managing epilepsy in women of childbearing age

Epilepsy affects the menstrual cycle, aspects of contraception, fertility, pregnancy and bone health in women. It is common for seizure frequency to vary throughout the menstrual cycle. In ovulatory cycles, two peaks can be seen around the time of ovulation and in the few days before menstruation. In anovulatory cycles, there is an increase in seizures during the second half of the menstrual cycle. There is also an increase in polycystic ovaries and hyperandrogenism associated with valproate therapy. There are no contraindications to the use of non-hormonal methods of contraception in women with epilepsy. Non-enzyme-inducing antiepileptic drugs (AEDs) [valproate, benzodiazepines, ethosuximide, levetiracetam, tiagabine and zonisamide] do not show any interactions with the combined oral contraceptive (OC). There are interactions between the combined OC and hepatic microsomal-inducing AEDs (phenytoin, barbiturates, carbamazepine, topiramate [dosages>200 mg/day], oxcarbazepine) and lamotrigine. Pre-conception counselling should be available to all women with epilepsy who are considering pregnancy. Women with epilepsy should be informed about issues relating to the future pregnancy, including methods and consequences of prenatal screening, fertility, genetics of their seizure disorder, teratogenicity of AEDs, folic acid and vitamin K supplements, labour, breast feeding and care of a child. During pregnancy, the lowest effective dose of the most appropriate AED should be used, aiming for monotherapy where possible. Recent pregnancy databases have suggested that valproate is significantly more teratogenic than carbamazepine, and the combination of valproate and lamotrigine is particularly teratogenic. Most pregnancies in women with epilepsy are without complications, and the majority of infants are delivered healthy with no increased risk of obstetric complications in women. There is no medical reason why a woman with epilepsy cannot breastfeed her child. The AED concentration profiled in breast milk follows the plasma concentration curve. The total amount of drug transferred to infants via breast milk is usually much smaller than the amount transferred via the placenta during pregnancy. However, as drug elimination mechanisms are not fully developed in early infancy, repeated administration of a drug such as lamotrigine via breast milk may lead to accumulation in the infant. Studies have suggested that women with epilepsy are at increased risk of fractures, osteoporosis and osteomalacia. No studies have been undertaken looking at preventative therapies for these co-morbidities.

Epilepsy pharmacogenetics

Large interindividual variation in efficacy and adverse effects of anti-epileptic therapy presents opportunities and challenges in pharmacogenomics. Although the first true association of genetic polymorphism in drug-metabolizing enzymes with anti-epileptic drug dose was reported 10 years ago, most of the findings have had little impact on clinical practice so far. Most studies performed to date examined candidate genes and were focused on candidate gene selection. Genome-wide association and whole-genome sequencing technologies empower hypothesis-free comprehensive screening of genetic variation across the genome and now the main challenge remaining is to select and study clinically relevant phenotypes suitable for genetic studies. Here we review the current state of epilepsy pharmacogenetics focusing on phenotyping questions and discuss what characteristics we need to study to get answers.

Female issues in epilepsy: a critical review

The focus on gender-related issues for women with epilepsy has heightened in recent years. The emphasis, however, has been on the childbearing years. Epilepsy and antiepileptic drug treatment affect sexual development, the menstrual cycle, and aspects of contraception, fertility, and reproduction. Female patients with epilepsy at a reproductive age face a unique set of reproductive issues, ranging from descriptions of disorders of reproduction in epilepsy and its causes, to contraception, pregnancy, sexuality, menopause, and osteoporosis. Conditions and diseases that specifically affect women are discussed. The role of hormones across the life cycle--endogenous and exogenous hormones and their effects on drug interactions, drug metabolism, and therapeutic outcomes--is described. Contraception and pregnancy issues for women with epilepsy have received the appropriate attention.

Teratogenesis associated with antibipolar agents

OBJECTIVE

To review the teratogenic effects associated with the use of Food and Drug Administration-approved agents for bipolar disorder.

METHODS

A PubMed search of all English language articles published from January 1966 to December 2008 was conducted. The key search terms included all major bipolar agents, cross-referenced with: teratogenicity, teratogen, safety, pregnancy, fetus, bipolar disorder, and malformation. The search was augmented with manual reviews of relevant article reference lists as well as http://clinicaltrials.gov and http://www.fda.gov (both last accessed in April 2008). Several pregnancy registries were also reviewed to determine malformation rates as well as teratogenesis attributable to each agent. Articles selected for review were based on author consensus, adequacy of sample size, the use of standardized experimental procedures, validated assessment measures, and overall manuscript quality.

RESULTS

Valproate is associated with the highest rate of major congenital malformations (6.2%-16%). The relative risk of neural tube defects with valproate and carbamazepine is reported as approximately 1%-5% and 0.5%-1%, respectively. Preliminary evidence suggests that the relative risk for oral clefts (cleft lip or palate) is increased with lamotrigine relative to other antiepileptic drugs (AED) (ie, approximately 0.4%). The rate of major congenital malformations is higher in fetuses exposed to AED polytherapy (ie, >or=2 drugs) in comparison with AED monotherapy. Adverse neurobehavioral effects are insufficiently reported for most agents. In-utero exposure to valproate is associated with a greater risk of developmental difficulty requiring special education interventions as well as decreased verbal IQ scores. The risk of Ebstein's anomaly associated with lithium use is increased relative to the general population. The major congenital malformation rate with chlorpromazine and atypical antipsychotics is not established as being higher than a non-exposed group; the teratogenic risks associated with the olanzapine-fluoxetine combination are unknown.

CONCLUSIONS

Well-characterized risks are associated with valproate, carbamazepine, lamotrigine, and lithium. The risks associated with psychotropic drug use need to be understood in the context of significant rates of relapse and associated morbidity when discontinuing bipolar treatment during pregnancy.

Anticonvulsant profile and teratogenicity of 3,3-dimethylbutanoylurea: a potential for a second generation drug to valproic acid

PURPOSE

The purpose of this study was to evaluate the anticonvulsant activity and teratogenic potential of branched aliphatic acylureas represented by isovaleroylurea (IVU), pivaloylurea (PVU) and 3,3-dimethylbutanoylurea (DBU), as potential second-generation drugs to valproic acid (VPA).

METHODS

The anticonvulsant activity of IVU, PVU, and DBU was determined in mice and rats utilizing the maximal electroshock seizure (MES) and the pentylenetetrazole (scMet) tests. The ability of DBU to block electrical-, or chemical-induced seizures was further examined in three acute seizure models: the psychomotor 6 Hz model, the bicuculline and picrotoxin models and one model of chronic epilepsy (i.e., the hippocampal kindled rat model). The induction of neural tube defects (NTDs) by IVU, PVU, and DBU was evaluated after i.p. administration at day 8.5 of gestation to a mouse strain highly susceptible to VPA-induced teratogenicity. The pharmacokinetics of DBU was studied following i.v. administration to rats.

RESULTS

DBU emerged as the most potent compound having an MES-ED(50)of 186 mg/kg (mice) and 64 mg/kg (rats) and an scMet-ED(50)of 66 mg/kg (mice) and 26 mg/kg (rats). DBU underwent further evaluation in the hippocampal kindled rat (ED(50)= 35 mg/kg), the psychomotor 6 Hz mouse model (ED(50)= 80 mg/kg at 32 mA and ED(50)= 133 mg/kg at 44 mA), the bicuculline- and picrotoxin-induced seizure mouse model (ED(50)= 205 mg/kg and 167 mg/kg, respectively). In contrast to VPA, DBU, IVU, and PVU did not induce a significant increase in NTDs as compared to control. DBU was eliminated by metabolism with a half-life of 4.5 h.

CONCLUSIONS

DBU's broad spectrum and potent anticonvulsant activity, along with its high safety margin and favorable pharmacokinetic profile, make it an attractive candidate to become a new, potent, and safe AED.

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.