Antiepileptic drug therapy and reproductive consequences: functional and morphologic effects

Determination of emerging chlorinated byproducts of diazepam in drinking water

Diazepam (DZP) is often found in source water and drinking water at dozens of nanograms per liter levels. The transformation of DZP in water chlorination disinfection process has aroused new concern because the toxic disinfection byproducts (DBPs) might be produced. However, the DBPs of DZP have not been fully identified, and their occurrence levels in drinking water have not been reported. In our chlorination experiment, five emerging DBPs of diazepam: (5-chloro-2-(methylamino) phenyl) (phenyl)methanone (BP-246), 6-chloro-1-methyl-4-phenylquinazolin-2(1H)-one (BP-271), N-(2-benzoyl-4,6-dichlorophenyl)formamide (BP-294), methyl-(2-benzoyl-4-chlorophenyl) (methyl)carbamate (BP-304 (1)) and 6-chloro-4-methoxy-1-methyl-4-phenyl-1,4-dihydro2H -benzo[d][1,3]oxazin-2-one (BP-304 (2)), were tentatively identified by high-resolution mass spectrometry and further characterized by nuclear magnetic resonance spectroscopy. We developed a trace analytical method for the analysis of these five DBPs in drinking water based on solid-phase extraction (SPE) followed liquid chromatography coupled with electrospray ionization tandem mass spectrometric detection. Ultrahigh sensitivities were achieved with limits of detection as low as 7 pg per liter. The recoveries at different spiking levels were all higher than 80% except for that of BP-246. Four of the DBPs and DZP were detected in real drinking water samples at concentrations ranging from several to dozens of nanograms per liter with relatively high detection frequencies. This is the first report on the existence of DZP-DBPs in drinking water. The method and results will be useful for further studies on the occurrence, toxicity, human exposure and control measures of these DBPs.

Neural tube defects: Risk factors and preventive measures

For the last 25 years, it has been proven that the occurrence or recurrence of neural tube defects can be prevented with the administration of folic acid before and early pregnancy. At present, over 80 countries in the world, except Japan, have mandated the fortification of wheat flour and/or rice with folic acid, which has resulted in a significant reduction in the prevalence of neural tube defects. In 2000, the Japanese government recommended folic acid 400 μg daily for young women of childbearing age and women who are planning to conceive. In 2002, the government started to present information about the importance of folic acid in the development of fetuses in the Mother-Child Health Booklet annually. Despite these endeavors, the prevalence of neural tube defects has remained unchanged. We discuss the risk factors of neural tube defects and propose preventive measures to decrease the number of neonates with neural tube defects. We believe that the government should implement the fortification of staple food with folic acid very soon, which will eventually decrease not only the neonatal mortality and morbidity, but also the economic burden on our health care system.

Genetic enhancement of microsomal epoxide hydrolase improves metabolic detoxification but impairs cerebral blood flow regulation

Microsomal epoxide hydrolase (mEH) is a detoxifying enzyme for xenobiotic compounds. Enzymatic activity of mEH can be greatly increased by a point mutation, leading to an E404D amino acid exchange in its catalytic triad. Surprisingly, this variant is not found in any vertebrate species, despite the obvious advantage of accelerated detoxification. We hypothesized that this evolutionary avoidance is due to the fact that the mEH plays a dualistic role in detoxification and control of endogenous vascular signaling molecules. To test this, we generated mEH E404D mice and assessed them for detoxification capacity and vascular dynamics. In liver microsomes from these mice, turnover of the xenobiotic compound phenanthrene-9,10-oxide was four times faster compared to WT liver microsomes, confirming accelerated detoxification. mEH E404D animals also showed faster metabolization of a specific class of endogenous eicosanoids, arachidonic acid-derived epoxyeicosatrienoic acids (EETs) to dihydroxyeicosatrienoic acids (DHETs). Significantly higher DHETs/EETs ratios were found in mEH E404D liver, urine, plasma, brain and cerebral endothelial cells compared to WT controls, suggesting a broad impact of the mEH mutant on endogenous EETs metabolism. Because EETs are strong vasodilators in cerebral vasculature, hemodynamics were assessed in mEH E404D and WT cerebral cortex and hippocampus using cerebral blood volume (CBV)-based functional magnetic resonance imaging (fMRI). Basal CBV₀ levels were similar between mEH E404D and control mice in both brain areas. But vascular reactivity and vasodilation in response to the vasodilatory drug acetazolamide were reduced in mEH E404D forebrain compared to WT controls by factor 3 and 2.6, respectively. These results demonstrate a critical role for mEH E404D in vasodynamics and suggest that deregulation of endogenous signaling pathways is the undesirable gain of function associated with the E404D variant.

Investigations of single nucleotide polymorphisms in folate pathway genes in Chinese families with neural tube defects

AIMS

We investigated the hypothesis that there are interactions between SNPs in folate metabolism pathway genes and environmental risk factors to the etiology of neural tube defects (NTDs).

METHOD

In 602 Chinese families, 609 aborted fetus tissues or blood samples were collected from NTD individuals, and 1106 parental blood samples were detected as controls. We analyzed 28 SNPs in 12 folate pathway genes. Folate supplementation, gestational diabetes mellitus (GDM) and medicine administration before and during pregnancy were investigated. Case-parental control study and transmission/disequilibrium tests were performed according to environmental cofactor stratification.

RESULTS

Association between 5,10-methylenetetrahydrofolate reductase (MTHFR) 677C>T and NTDs was significant in all stratifications (all P<.05), and synergistic effects of no folate supplementation and GDM were shown on NTD occurrence. 5-Methyltetrahydrofolate-homocysteine methyltransferase (MTHM) 501A>G in case of GDM, and betaine-homocysteine methyltransferase (BHMT) 716G>A in case of no folate supplementation significantly associated with NTDs (both P<.05), whereas the two genotypes alone did not significantly associate with NTDs (both P>.05).

CONCLUSIONS

MTHFR 677C>T genotype, especially in case of no folate supplementation and GDM, promotes NTD occurrence. MTHM 501A>G only in case of GDM, and BHMT 716G>A only in case of no folate supplementation contribute to the etiology of NTDs.

Pharmacology and pharmacogenomics of neurological medications used in pregnancy

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

A case of Moebius syndrome presenting with congenital bilateral vocal cord paralysis

We describe a female infant with bilateral facial paralysis and abducens palsy. To the best of our knowledge, this is the first report of Moebius syndrome presenting with congenital bilateral vocal cord paralysis (CBVCP). Although CBVCP can be part of a recognizable syndrome, i.e. Down syndrome, 22q deletion syndrome, Robinow's syndrome and cerebro-oculo-facio-skeletal syndrome, no reports of Moebius syndrome with CBVCP were found in the literature. CBVCP is often associated with central nervous system abnormalities. However, our patient had no detectable brain abnormalities. The etiology of Moebius syndrome remains unknown. It is interesting that the clinical manifestations of Moebius syndrome can include CBVCP. However, the pathophysiology of CBVCP is unknown and further investigations into the etiology of Moebius syndrome are required.

Cardiovascular malformations induced by prenatal exposure to phenobarbital in rats

The effects of prenatal exposure to phenobarbital (PB) on the cardiovascular system were examined in rat fetuses and pups. PB was administered at a dose of 80 or 120 mg/kg/day by gavage to Sprague Dawley (SD) rats on two consecutive gestational days (GD): 7-8, 8-9, 9-10, or 10-11. Fetuses were examined for cardiovascular malformations on GD 20. In addition, pups were examined for PB-induced cardiovascular malformations. Incidences of ventricular septal defect (VSD), overriding aorta, double outlet right ventricle and transposition of great arteries were significantly increased in the fetuses whose dams were administered PB at 120 mg/kg on GD 8-9, 9-10 or 10-11. GD 8-11 was the critical period for the cardiovascular malformations associated with administration of PB in rats. Various types of cardiovascular malformations were detected in pups from the PB-administered dam. Severe cardiovascular malformations induced by PB caused deaths on early postnatal days. However, slight malformations such as isolated VSD persisted until weaning, and did not affect postnatal viability.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Neurotoxic damage of granule cells in the dentate gyrus and the cerebellum and cognitive deficit following neonatal administration of phenytoin in mice

The use of antiepileptic drugs during human gestation probably increases the risk of causing CNS disorders in later life. In brain, granule cells in the dentate gyrus (DG) and cerebellum are still developing in the last trimester of human gestation and a similar development is taking place during the mouse perinatal period. We treated newborn C57BL/6 mice orally with 35 mg/kg phenytoin (PHT) daily during postnatal days (PD) 5 to 14. Histopathological investigation revealed that the layer of mature granule cells in the DG that was immunoreactive to anti-calbindin D28k was thinner in PHT-treated mice. Purkinje cells in the treated group also had poor, immature arbors with an irregular arrangement. A number of TUNEL-positive cells were observed in the DG and cerebellum during the treatment. PHT-treated mice were impaired in the acquisition of a hidden platform task in the water maze and committed significantly more errors during the learning process in theradial arm maze. These findings demonstrate that neonatal administration of PHT interferes with the development of granule cells in the hippocampus and the cerebellum and causes spatial leaning deficits in later life. Cautious clinical use of this drug for pregnant patients is warranted, especially in the last trimester.

Epilepsy, pregnancy, and the child

Women with epilepsy have many legitimate concerns regarding the effects of their condition and the use of antiepileptic drugs (AEDs) on their unborn children. These concerns fall into 4 areas: increased seizure frequency during pregnancy, risk of birth defects, risks associated with breastfeeding, and psychomotor retardation in offspring. Studies have shown that many of these risks can be minimized with appropriate management and counseling. Data also show that psychomotor retardation in offspring of mothers with epilepsy is generally transitory. In this article, associations between maternal use of AEDs, birth defects, intrauterine growth retardation, and the psychomotor development are discussed together with how best to alter AED therapy to minimize them.

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.

Role of gene knockout mice in understanding the mechanisms of chemical toxicity and carcinogenesis

Most chemical carcinogens require metabolic activation to electrophilic metabolites that are capable of binding to DNA and causing gene mutation. Carcinogen metabolism is carried out by large groups of xenobiotic-metabolizing enzymes that include the phase I cytochromes P450 (P450) and phase II enzymes that include various transferases. During the past 10 years, considerable attention has been focused on the role of P450s in human cancer susceptibility. Polymorphisms in expression of P450s and transferases exist in humans and these might render increased susceptibility or resistance to cancer. Thus it is important to understanding how P450s participate in the carcinogenesis process and to determine if they are indeed the rate limiting and critical interface between the chemical and its biological activity. Since there are marked species differences in expressions and catalytic activities of the multiple P450 forms that activate carcinogens, this validation process becomes especially difficult. To address the role of P450s in whole animal carcinogenesis, mice were produced that lack the P450s known to catalyze carcinogen activation. Mouse lines having disruption of genes encoding P450s CYP1A2, CYP2E1, and CYP1B1 were developed by use of gene disruption in empbryonic stem cells. Mice lacking expression of microsomal epoxide hydrolase and NADPH:quinone oxidoreductase were also made. These mice exhibit no grossly abnormal phenotypes, suggesting that the xenobiotic-metabolizing enzymes have no critical roles in mammalian development and physiological homeostasis. This explains the occurrence of polymorphisms in humans and other mammalian species. However, these null mice do show differences in sensitivities to acute chemical toxicities, thus establishing the importance of xenobiotic metabolism in activation pathways that lead to cell death. Rodent bioassays using null mice and known genotoxic carcinogens should establish whether these enzymes are required for carcinogenesis in an intact animal model. These studies will also provide a framework for the production of transgenic mice and carcinogen bioassay protocols that may be more predictive for identifying human carcinogens and validate the molecular epidemiology studies ongoing in humans that seek to establish a role for polymorphisms in cancer risk.

Targeted disruption of the microsomal epoxide hydrolase gene. Microsomal epoxide hydrolase is required for the carcinogenic activity of 7,12-dimethylbenz[a]anthracene

Microsomal epoxide hydrolase (mEH) is a conserved enzyme that is known to hydrolyze many drugs and carcinogens, and a few endogenous steroids and bile acids. mEH-null mice were produced and found to be fertile and have no phenotypic abnormalities thus indicating that mEH is not critical for reproduction and physiological homeostasis. mEH has also been implicated in participating in the metabolic activation of polycyclic aromatic hydrocarbon carcinogens. Embryonic fibroblast derived from the mEH-null mice were unable to produce the proximate carcinogenic metabolite of 7,12-dimethylbenz[a]anthracene (DMBA), a widely studied experimental prototype for the polycylic aromatic hydrocarbon class of chemical carcinogens. They were also resistant to DMBA-mediated toxicity. Using the two-stage initiation-promotion skin cancer bioassay, the mEH-null mice were found to be highly resistant to DMBA-induced carcinogenesis. In a complete carcinogenesis bioassay, the mEH mice were totally resistant to tumorigenesis. These data establish in an intact animal model that mEH is a key genetic determinant in DMBA carcinogenesis through its role in production of the ultimate carcinogenic metabolite of DMBA, the 3,4-diol-1,2-epoxide.

The expression and regulation of drug metabolism in human placenta

The human placenta oxidizes several xenobiotics, although the spectrum of substrates and metabolic activities when compared with the liver appears restricted. Maternal cigarette smoking or PCB exposure increase the expression of CYP1A1. This induced activity is able to catalyze the activation of benzo(a)pyrene into DNA-bound adducts, both in vitro and in vivo. Studies with RT-PCR technique have demonstrated that first trimester placentae express at the mRNA level CYP1A1, 1A2, 2C, 2D6, 2E1, 2F1, 3A4, 3A5, 3A7 and 4B1 and at full term CYP1A1, 2E1, 2F1, 3A3/4, 3A5 and 3A7. However, more detailed studies on cDNA probes or with specific antibodies or 'diagnostic' substrates for other than CYP1A1, 2E1 and 3A gene products have yielded negative results. Studies on human placenta and a chorioncarcinoma cell line, JEG 3 cells, boulster the concept that placental CYP1A1 and 1B1 - although their expression is Ah receptor and ARNT mediated - is controlled by distinct mechanisms. Aromatase, CYP19, and cholesterol side-chain cleaving, CYP11B, genes, proteins and activities are catalytically active in human placentae throughout the pregnancy and those parameters do not seem to be affected by maternal cigarette smoking but rather maternal health status. However, the substrate binding pocket of aromatase accepts as its substrate several xenobiotics and is responsible for constitutive xenobiotic biotransformations.Functional placental glutathione S-transferase, N-acetyl transferase and epoxide hydrolase are expressed via one gene each and their function reflects the placenta as an endocrine organ rather than a xenobiotic-metabolizing unit. However, markers for oxidative stress can be detected in decreased glutathione S-transferase activities.Because human placenta has quite well defined metabolic characteristics, and obtaining placental samples will not meet any drastic ethical difficulties, it could be used more intensively as a source of metabolizing enzymes in in vitro studies during the course of a drug development program. The human placenta, or its subcellular organelles, could serve as a real alternative model for an extrahepatic tissue in replacing recombinant expression systems especially if CYP11, 19, 1A1 or potentially 2E1 are target enzymes for potential metabolic interactions.

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.

Congenital malformations due to antiepileptic drugs

To identify the major risk factors for the increased incidence of congenital malformations in offspring of mothers being treated for epilepsy with antiepileptic drugs (AEDs) during pregnancy and, to determine the relative teratogenic risk of AEDs, we prospectively analyzed 983 offspring born in Japan, Italy, and Canada. The incidence of congenital malformations in offspring without drug exposure was 3.1%, versus an incidence with drug exposure of 9.0%. The highest incidence in offspring exposed to a single AED occurred with primidone (PRM; 14.3%), which was followed by valproate (VPA; 11.1%), phenytoin (PHT; 9.1%), carbamazepine (CBZ; 5.7%), and phenobarbital (PB; 5.1%). The VPA dose and level positively correlated with the incidence of malformations. This study first determined a cut-off value of VPA dose and level at 1000 mg/day and 70 microg/ml, respectively, to avoid the occurrence of malformations. The incidence of malformations increases as the number of drugs increases, and as the total daily dose increases. Specific combinations of AEDs such as VPA + CBZ and PHT + PRM + PB produced a higher incidence of congenital malformations. The incidence of malformations was not associated with any background factors studied except for the presence of malformations in siblings. These results indicate that the increased incidence of congenital malformations was caused primarily by AEDs, suggesting that malformations can be prevented by improvements in drug regimen, and by avoiding polypharmacy and high levels of VPA (more than 70 microg/ml) in the treatment of epileptic women of childbearimg age.

Pregnancy and quality of life in women with epilepsy

Women with epilepsy have many legitimate concerns regarding the effects of their condition and the use of antiepileptic drugs (AEDs) on their unborn children. These concerns fall into four areas: increased seizure frequency, risk of birth defects, risks associated with breast-feeding, and psychomotor retardation associated with AED use. Studies have shown that many of these risks can be minimized with appropriate management and counseling. This review describes some of the data regarding these risks and how best to alter AED therapy to minimize them. It also reviews data showing that psychomotor retardation is generally transitory.

Long-term consequences of neonatal exposure to diazepam on cerebral glucose utilization, learning, memory and anxiety

The long-term consequences of neonatal exposure to diazepam (DZP) on behavioral abilities and local cerebral glucose utilization (LCGU) in 12 brain regions involved in the control of memory and anxiety were studied in adult rats. Rat pups received a daily subcutaneous injection of 10 mg/kg DZP or of the dissolution vehicle from postnatal day (P) 2 to 21. Learning and memory were tested in P60-P70 rats over 5 consecutive days in a T maze and an eight-arm maze while anxiety and reaction to novelty were tested in a two-compartment box with a two-step staircase on the enriched side. LCGU was measured in the P60 rat by the quantitative autoradiographic [14C]deoxyglucose method. In the T maze, when performed without delay between the two trials, the rate of alternation was significantly lower in DZP- than in vehicle-exposed rats on the first 2 days of testing and similar in both groups on days 3-5. In the procedure with a 30 s intertrial delay, the rate of alternation was similar in DZP- and vehicle-treated rats on all days of testing. In the eight-arm maze, DZP-treated rats were more active, i.e., entered more arms per minute than control animals. The number of arms entered before the first error was lower on day 1 and higher on day 3 in DZP- compared to vehicle-exposed rats. In the two-compartment box, DZP-treated rats crossed more often and spent more time than controls on the lower step of the staircase while control rats made more rearings and spent more time than DZP-exposed rats in the well protected corner of the box. LCGU were decreased by early DZP exposure in six regions which were mammillary body, septum, visual and prefrontal cortices, dorsomedian caudate nucleus and mediodorsal thalamus. In conclusion, postnatal DZP treatment induced at adulthood an increase in activity, a delay in task acquisition but no learning-memory impairment and reduced the level of anxiety allowing active responding to novelty. These quite subtle behavioral changes were accompanied by discrete metabolic decreases in regions mediating anxiety, reflecting a change in the level of anxiety and emotionality.

Preliminary report on teratogenic effects of zonisamide in the offspring of treated women with epilepsy

PURPOSE

We wished to assess the risk of teratogenicity of zonisamide (ZNS) in humans.

METHODS

Pregnant epileptic women treated with ZNS and their offspring were prospectively monitored from June 1989 to December 1994. The outcome of pregnancy and status of neonates were examined based on the same standardized protocol.

RESULTS

Twenty-six offspring exposed to ZNS with or without other antiepileptic drugs (AEDs) were studied. Malformations were detected in 2 offspring (7.7%) exposed to ZNS polypharmacy. Anencephaly was detected in one case at 16 weeks of gestation (case 1, artificial abortion), and atrial septal defect was detected in another case at 37 weeks of gestation (case 2, delivery by cesarean section). Serum concentrations of ZNS during the first trimester of pregnancy were 6.1 micrograms/ml in case 1 and 6.3 micrograms/ml in case 2; in both cases, the levels were below the therapeutic concentration range of ZNS.

CONCLUSIONS

Teratogenic effects of ZNS were not clearly defined from these results since malformations were detected in two polypharmacy cases but not in four monopharmacy cases. The present data do not indicate that the risk of ZNS teratogenicity is greater than that of other conventional AEDs. However, such risk cannot be neglected even at therapeutic dosages or concentrations of ZNS, especially in patients receiving poly-pharmacy.

Short- and long-term effects of neonatal diazepam exposure on local cerebral glucose utilization in the rat

The short- and long-term consequences of a neonatal exposure to diazepam (DZP) on the postnatal changes in local cerebral metabolic rates for glucose (LCMRglcs) were studied by the quantitative autoradiographic [14C]2-deoxyglucose method in a total number of 66 brain structures of freely moving rats. Rat pups received a daily subcutaneous injection of 10 mg/kg DZP, of the dissolution vehicle or of saline from postnatal day 2 (P2) to 21 (P21). The animals were studied at 4 ages, P10, P14, P21 and P60. DZP induced a decrease in LCMRglcs which was restricted to 13 areas at P10, mainly sensory and limbic regions. At P14, the treatment had significant metabolic effects on 48 structures belonging to all functional systems. By P21, 23 brain areas were still affected by the treatment, mainly sensory, limbic and motor areas. At P60, i.e. at about 40 days after the end of drug exposure, LCMRglcs still decreased in 14 brain regions which were mainly sensory and limbic structures. The structures most sensitive to both short- and long-term consequences of the anticonvulsant treatment are mammillary body, limbic cortices and sensory regions. The dissolution vehicle increased LCMRglcs in a few brain regions at P14 and P60, whereas it decreased metabolic levels in 5 brain regions at P21. The results of the present study show that the brain appears to be particularly vulnerable to the treatment at P14, period of active brain growth, whereas by P21, the drug is actively metabolized and a tolerance to the treatment may occur. The long-term effects of the treatment are in good accordance with the well-known effects of DZP on anxiety, sedation and memory. The structures most sensitive to early neonatal DZP exposure are the mammillary body, limbic cortices and sensory regions that all contain a high density of benzodiazepine binding sites.

Effects of early chronic diazepam treatment on incorporation of glucose and beta-hydroxybutyrate into cerebral amino acids: relation to undernutrition

The effects of early chronic diazepam (DZP) exposure on blood glucose and ketone body concentration and glucose and beta-hydroxybutyrate (beta HB) utilization for regional cerebral amino acid biosynthesis were studied in suckling rats. The animals were treated from postnatal day 2 (P2) to 21 (P21) by a daily subcutaneous injection of 10 mg/kg DZP or of the dissolution vehicle and studied at P5, P10, P14 and P21, together with an additional group of food-restricted rats obtained by an increase in litter size. DZP treatment induced a 9-26% decrease in body and brain weight. Undernutrition decreased body weight by 20-24% at all ages whereas brain weight was relatively spared. DZP and N-desmethyldiazepam concentrations decreased with age and were cleared from brain and plasma by 6-8 hrs after the injection. DZP decreased plasma glucose concentrations by 6-12% at P5, P14 and P21, whereas undernutrition did not change plasma glucose concentrations, except for a 7% decrease at P14. DZP treatment had no consequences on circulating concentrations of both ketone bodies while undernutrition increased their concentration by 45-362% at all ages. The conversion of [14C]glucose into cerebral amino acids was reduced by DZP at P5 and P10. The cerebral concentration of neurotransmitter amino acids was not affected by DZP treatment which only increased the amount of neutral amino acids mainly in the cerebellum at P5 and P10. After [U-14C]glucose injection, specific radioactivities of cerebral amino acids were mostly decreased by DZP from P5 to P14 and significantly increased at P21. With [3-14C] beta HB as a precursor, specific radioactivities of neurotransmitter amino acids were increased by DZP. In conclusion, P5 and P10 rats appear to be most sensitive to DZP effects whereas some tolerance to the drug seems to develop by P21. The lack of effects of DZP on blood ketone body concentrations compared to food restriction as well as the relative sparing of brain weight in undernourished rats confirms that the cerebral metabolic consequences of early DZP exposure on brain energy metabolism are mostly direct effects not mediated by sedation-induced undernutrition.

Teratogenicity of antiepileptic drugs: is the prevention possible?

To assess the relative contribution of antiepileptic drugs (AEDs) toward the occurrence of congenital malformation, two prospective studies (previous and present) were compared. In the present subjects of 145 cases, the total daily dose of AEDs (drug score) in each case was decreased as much as possible, and polypharmacy was changed to monopharmacy before conception where it was possible. The incidence of malformations significantly decreased from 13.5% to 6.2% (p = 0.031) by the change in drug regimen. The drug score, number of AEDs, maternal age at delivery, seizure type, and etiology of epilepsy were statistically different between the two study groups. Even after the correction of the data by the last three factors, the difference in the incidence of malformation did not disappear, while it disappeared if data were corrected either by the drug score or number of AEDs. These results suggest that the possibility of prevention of AED related malformations is possible by an improvement in AED therapy.