Decreased bone mass and increased bone turnover with valproate therapy in adults with epilepsy

Bone mineral density in subjects using central nervous system-active medications

PURPOSE

Decreased bone mineral density defines osteoporosis according to the World Health Organization and is an important predictor of future fractures. The use of several types of central nervous system-active drugs, including benzodiazepines, anticonvulsants, antidepressants, and opioids, have all been associated with increased risk of fracture. However, it is unclear whether such an increase in risk is related to an effect of bone mineral density or to other factors, such as increased risk of falls. We sought to examine the relationship between bone mineral density and the use of benzodiazepines, anticonvulsants, antidepressants, and opioids in a representative US population-based sample.

SUBJECTS AND METHODS

We analyzed data on adults aged 17 years and older from the Third National Health and Nutrition Examination Survey (NHANES III, 1988-1994). Total femoral bone mineral density of 7114 male and 7532 female participants was measured by dual-energy x-ray absorptiometry. Multivariable linear regression models were used to quantify the relation between central nervous system medication exposure and total femoral bone mineral density. Models controlled for relevant covariates, including age, sex, and body mass index.

RESULTS

In linear regression models, significantly reduced bone mineral density was found in subjects taking anticonvulsants (0.92 g/cm2; 95% confidence interval [CI]: 0.89 to 0.94) and opioids (0.92 g/cm2; 95% CI: 0.88 to 0.95) compared with nonusers (0.95 g/cm2; 95% CI: 0.95 to 0.95) after adjusting for several potential confounders. The other central nervous system-active drugs--benzodiazepines or antidepressants--were not associated with significantly reduced bone mineral density.

CONCLUSION

In cross-sectional analysis of NHANES III, anticonvulsants and opioids (but not benzodiazepines or antidepressants) were associated with significantly reduced bone mineral density. These findings have implications for fracture-prevention strategies.

Induction of endogenous pathways by antiepileptics and clinical implications

The aim of this study was to review modifications of the endogenous pathways (e.g. enzyme elevations, normal body constituent depletion or higher formation/excretion of endogenous metabolites) which could be ascribed to enzyme induction by antiepileptic drugs (AEDs). Information on older (e.g. phenobarbital, phenytoin and carbamazepine) and newer drugs (where information is available) is discussed together with clinical implications. The enzymes involved in the endogenous pathways and induced by the AEDs will not be limited to the hepatic microsomal enzymes; extrahepatic enzymes and/or enzymes present in other subcellular fractions will also be discussed, if pertinent. The induction of endogenous pathways by AEDs has been taken into account in the past, but much less emphasis has been given compared with the extensive literature on induction by AEDs of the metabolism of concomitantly administered drugs, either of the same or of different classes. Not all of the endogenous pathways examined and induced by AEDs appear to result in serious clinical consequences (e.g. induction of hepatic ALP, increased excretion of d-glucaric acid or of 6 beta-hydroxycortisol). In some cases, induction of some pathways (e.g. increase of high-density lipoprotein cholesterol or of conjugated bilirubin) might even be a beneficial side-effect, however enzyme induction is considered rather a detrimental aspect for an AED, as induction is generally a broad and a non-specific phenomenon. The new AEDs have generally less induction potential than the older agents. Yet some (felbamate, topiramate, oxcarbazepine and lamotrigine) have the potential for inducing enzymes, whereas others (levetiracetam, gabapentin and vigabatrin) appear to be completely devoid of enzyme inducing characteristics, at least as far as the enzymes investigated are concerned.

Multiple mechanisms induce transcriptional silencing of a subset of genes, including oestrogen receptor alpha, in response to deacetylase inhibition by valproic acid and trichostatin A

Valproate (VPA) and trichostatin A (TSA), inhibitors of zinc-dependent deacetylase activity, induce reduction in the levels of mRNA encoding oestrogen receptor-alpha (ERalpha), resulting in subsequent clearance of ERalpha protein from breast and ovarian cell lines. Inhibition of oestrogen signalling may account for the endocrine disorders, menstrual abnormalities, osteoporosis and weight gain that occur in a proportion of women treated with VPA for epilepsy or for bipolar mood disorder. Transcriptome profiling revealed that VPA and TSA also modulate the expression of, among others, key regulatory components of the cell cycle. Meta-analysis of genes directly responsive to oestrogen indicates that VPA and TSA have a generally antioestrogenic profile in ERalpha positive cells. Concomitant treatment with cycloheximide prevented most of these changes in gene expression, including downregulation of ERalpha mRNA, indicating that a limited number of genes signal a hyperacetylated state within cells. Three members of the NAD-dependent deacetylases, the sirtuins, are upregulated by VPA and by TSA and sirtuin activity contributes to loss of ERalpha expression. However, prolonged inhibition of the sirtuins by sirtinol also induces loss of ERalpha from cells. Mechanistically, we show that VPA invokes reversible promoter shutoff of the ERalpha, pS2 and cyclin D1 promoters, by inducing recruitment of methyl cytosine binding protein 2 (MeCP2) with concomitant exclusion of the maintenance methylase DNMT1. Furthermore, we demonstrate that, in the presence of VPA, local DNA methylation, deacetylation and demethylation of activated histones and recruitment of inhibitory complexes occurs on the pS2 promoter.

Effects of treatment on endocrine function in patients with epilepsy

Antiepileptic drug (AED) treatment is associated with multiple short- and long-term side effects. Effects on endocrine function, including weight change, reproductive function, thyroid function, and bone health are examples of these side effects. Some AEDs affect weight, resulting in weight gain or loss. Levetiracetam and lamotrigine are weight-neutral agents, whereas valproate is associated with weight gain. Reproductive dysfunction is reported in women and men with epilepsy treated with AEDs. In women, the most common symptoms are hyperandrogenism, menstrual disorders with ovulatory failure, polycystic ovary-appearing ovaries or polycystic ovary syndrome, and hyperinsulinemia. These symptoms may be secondary to epilepsy or to AED treatment, particularly with valproate. In men, effects on sperm quality and motility, delayed sexual development, and small testicular size have been described in association with AED treatment. Carbamazepine reduces testosterone levels, whereas valproate increases androgen levels. Oxcarbazepine is not associated with changes in testosterone levels. Treatment with all of these agents can result in changes in sperm, including concentration, morphology, and motility. Enzyme-inducing AEDs are known to result in decreased thyroid hormones. Recent studies found reduced serum thyroid hormone concentrations in men and young girls treated with carbamazepine and oxcarbazepine. However, all patients were clinically euthyroid, and these changes were reversible after AED withdrawal. Persons with epilepsy treated with AEDs are at increased risk for fracture. Not only is this increased because of seizure activity, but also because of treatment with AEDs. AED treatment results in decreased bone mineral density, the most sensitive predictor of fracture and changes in biochemical indices of bone metabolism, including calcium, vitamin D, and markers of bone formation and resorption. Identifying each of these endocrine abnormalities is important because it may be necessary and beneficial to change AED treatment. In addition, multiple therapies exist for the treatment of polycystic ovary syndrome, infertility, and decreased bone mineral density.

An analysis of lifetime fractures in women with epilepsy

OBJECTIVE

To clarify the relationship between fractures and antiepileptic drug (AED) use.

METHODS

Menopausal women with epilepsy were interviewed at two clinics regarding site, year and circumstances of any fracture, duration of AED use and menopause. Fracture sites were analyzed according to AED use.

RESULTS

Twenty-nine fractures occurred in 20 of the 50 interviewed subjects (mean age 54). Nine occurred prior to AEDs; seven attributed to accident and two to clumsiness. Twenty occurred on AEDs; 10 attributed to clumsiness (most in the leg and foot), eight to seizure (most in the arm or hand) and two to accident. Duration of AED exposure was similar in both groups and in osteoporotic vs non-osteoporotic sites.

CONCLUSIONS

Epilepsy therapy may contribute more to the lifetime occurrence of fracture than seizures themselves. More screening for osteoporosis is required. While adjusting doses to prevent seizures, ongoing screening for neurotoxicity must be maintained in order to avoid fractures.

Bone mass and turnover in women with epilepsy on antiepileptic drug monotherapy

Antiepileptic drugs, particularly cytochrome P450 enzyme inducers, are associated with disorders of bone metabolism. We studied premenopausal women with epilepsy receiving antiepileptic drug monotherapy (phenytoin, carbamazepine, valproate, and lamotrigine). Subjects completed exercise and nutrition questionnaires and bone mineral density studies. Serum was analyzed for indices of bone metabolism including calcium, 25-hydroxyvitamin D, parathyroid hormone, insulin growth factor I, insulin binding protein III, and bone formation markers, bone-specific alkaline phosphatase, and osteocalcin. Urine was analyzed for cross-linked N-telopeptide of type I collagen, a bone resorption marker. Calcium concentrations were significantly less in subjects receiving carbamazepine, phenytoin, and valproate than in those receiving lamotrigine (p = 0.008). Insulin growth factor-I was significantly reduced in subjects receiving phenytoin compared with those receiving lamotrigine (p = 0.017). Subjects receiving phenytoin had significantly greater levels of bone-specific alkaline phosphatase (p = 0.007). Our results demonstrate that phenytoin is associated with changes in bone metabolism and increased bone turnover. The lower calcium concentrations in subjects taking carbamazepine or valproate compared with those taking other antiepileptic drugs suggest that these antiepileptic drugs may have long-term effects. Subjects receiving lamotrigine had no significant reductions in calcium or increases in markers of bone turnover, suggesting this agent is less likely to have long-term adverse effects on bone.

Bone mineral density and serum levels of 25 OH vitamin D in chronic users of antiepileptic drugs

The aim of this cross sectional study was to evaluate bone mineral density (BMD) and serum levels of 25-hydroxy vitamin D (25OHD) in a group of patients taking antiepileptic drugs (AED) for a seizure disorder. Between May-2001 and January-2003, we evaluated 58 patients (40 women/18 men), 34.4+/-6 years old living in Curitiba or in its metropolitan area, on antiepileptic therapy for 2 to 38 years (10 on monotherapy /48 on multiple drugs regime). The group was matched by age, gender, and bone mass index to 29 healthy subjects (20 women/ 9 men); 34.2+/-5.9 years old. Medical history and physical exam were performed on all subjects with particular information sought about fractures and risks factors for osteoporosis. Blood samples were collected for total serum calcium, albumin, phosphorus, creatinine, total alkaline phosphatase, and liver function tests. BMD of the lumbar spine, femur and forearm was determined by dual energy X-ray absorptiometry (DXA, Hologic QDR 1000). Between February and April-2003, other blood samples were collected to measure 25OHD, intact paratohormone (PTH) and calcium. Unemployment and smoking history were more frequent among patients than among controls (p<0.05). Fifteen patients had a fracture history, all of which occurred during a seizure. The BMD of the lumbar spine (0.975+/-0. 13 g/cm2 vs. 1.058+/-0.1 g/cm2; p<0.03) and of the total femur (0.930+/-0.1 g/cm2 vs. 0.988+/-0.12 g/cm2; p<0.02) was lower in patients than in controls. In 63.5% of patients and in 24.1 % of controls a T-score < -1.0 in at least one site was seen. The AED users had higher total alkaline phosphatase and lower 25OHD (p<0.02). No correlations between BMD and 25OHD were found. The use of phenytoin was correlated with a greater incidence of fractures (RR: 2.38). We conclude that patients on chronic use of AED have alterations in bone metabolism characterized in this study by lower BMD of the lumbar spine and total femur and lower serum concentrations of 25OHD.

Current drug treatment of epilepsy in adults

The choice of antiepileptic drugs (AEDs) is rapidly increasing. This review looks at the evidence that guides the decision of which AED to start as monotherapy and aims to aid the choice of treatment if monotherapy fails. Unfortunately, the evidence supporting the prescribing of new drugs is sparse, because most randomised controlled trials answer questions focused on regulatory requirements rather than on clinical use. Ultimately, the choice of one AED will be determined by an individual risk-benefit assessment in which the most effective drug for an individual patient is chosen, and one that would have the lowest risk of significant harm. It is the risk of chronic toxic effects and issues of teratogenicity for women that may affect the choice of drug therapy to the greatest degree. In the future there is a need to improve the quality of clinical data on efficacy and harmful effects of AEDs.

Osteoporosis in women with disabilities

Women with physical and cognitive disabilities are at high risk for osteoporosis and osteoporosis-related fractures. Women with physical disabilities frequently are nonambulatory and have bone loss due to immobility. Women with cognitive disabilities have high rates of osteopenia and osteoporosis, likely partially due to high rates of anticonvulsant medication use. Women with Down syndrome are at especially high risk of osteopenia and osteoporosis, possibly because of lower peak bone density levels. Prevention of osteoporosis and related fractures in this population includes population-based measures, such as calcium and vitamin D supplementation and risk-based screening procedures. Primary care providers and specialists need to prioritize osteoporosis prevention strategies when taking care of women with disabilities. Future research is needed to determine optimal screening and prevention strategies in this very high risk population.

Bone disease in epilepsy

Recent literature demonstrates an association between antiepileptic drugs (AEDs) and bone disease. Decreased bone mineral density (BMD) has been found in adults and children receiving both enzyme-inducing AEDs and valproate, which is an enzyme-inhibiting AED. Biochemical abnormalities include hypocalcemia, elevated parathyroid hormone, and elevated markers of bone formation and resorption. Although patients in earlier studies had evidence of decreased vitamin D, low BMD has been found to be independent of abnormal vitamin D chemistries in more recently published studies. Multiple mechanisms have been postulated to explain AED-associated bone disease, but no single mechanism fully explains all the abnormalities seen. Therapies are available for bone disease. However, few studies have evaluated the effects of treatment in bone disease associated with AEDs.

Antiepileptic drugs and reduced bone mineral density

There is a growing interest in recognizing the association between antiepileptic drugs and reduced bone mineral density. Although the literature regarding this association has been available for more than three decades, the management of this complication remains unclear. We review the relevant literature regarding antiepileptic drugs and reduction in bone mineral density with the aim of developing some guidelines for practical management of this problem. This review focuses on the mechanism of antiepileptic drug-induced bone loss, its recognition, and its management.

Pathophysiology of bone loss in patients receiving anticonvulsant therapy

Many studies have shown that patients taking antiepileptic drugs (AEDs) are at increased risk for metabolic bone disease and low bone mineral density. Although early reports of bone disease in patients with epilepsy often involved institutionalized patients, who may be at risk because of lack of physical activity, reduced sunlight exposure, and poor nutrition, low bone density has also been reported in well-nourished, ambulatory outpatients with epilepsy. Traditionally, attention to the problem of AED-induced bone loss has been focused on those drugs that induce the hepatic cytochrome P450 enzyme system, thereby increasing the metabolism of vitamin D. However, the mechanisms of AED-induced bone loss appear to be multiple, and all types of AEDs are potentially implicated. Besides hepatic enzyme induction, mechanisms may include direct effects of AEDs on bone cells, resistance to parathyroid hormone, inhibition of calcitonin secretion, and impaired calcium absorption. An understanding of bone biology and the pathophysiology of bone loss can aid in the identification and monitoring of patients at risk and in the planning of appropriate prophylactic and therapeutic measures, by which most of the morbidity associated with AED-induced bone loss can be prevented.

Bone health in pediatric epilepsy

Childhood and adolescence are critical periods of skeletal mineralization. Peak bone mineral density achieved by the end of adolescence determines the risk for later pathological fractures and osteoporosis. Chronic disease and medication often adversely affect bone health. Epilepsy is one of the most common neurological conditions occurring in persons under the age of 21. Epilepsy may affect bone in a number of ways. Restrictions of physical activity imposed by seizures; limitations on physical activity resulting from cerebral palsy, frequently present in patients with symptomatic epilepsy; and medications used to treat seizures can all adversely affect bone health. It has long been observed that treatment with phenytoin and phenobarbital can be associated with rickets. More recently, established agents such as carbamazepine and valproate have been shown to be associated with a lowering of bone mineral density. The literature related to bone health in pediatric epilepsy is reviewed, although it should be noted that these data are limited.

Fractures, epilepsy, and antiepileptic drugs

The risk for skeletal fractures in patients with epilepsy is two to six times greater than in the general population. Fractures may be caused by seizures themselves or by falls, with or without seizures. Side effects of antiepileptic drugs (AEDs), such as ataxia, and coexisting neurological deficits contribute to the risk for falls. The effects of older AEDs on bone mineral density probably increase the risk for fractures associated with seizures and falls. Preventive measures include optimal control of seizures and supplementation with calcium and vitamin D. Whether newer AEDs prove to be without adverse effects on bone mineral metabolism remains to be determined.

Epilepsy and bone health in adults

Adults taking antiepileptic drugs (AEDs) have an augmented risk for osteopenia and osteoporosis because of abnormalities of bone metabolism associated with AEDs. The increased fracture rates that have been described among patients with epilepsy may be related both to seizures and to AEDs. The hepatic enzyme-inducing AEDs phenytoin, phenobarbital, and primidone have the clearest association with decreased bone mineral density (BMD). Carbamazepine, also an enzyme-inducing drug, and valproate, an enzyme inhibitor, may also adversely affect bone, but further study is needed. Little information is available about specific effects of newer AEDs on bone. Physicians are insufficiently aware of the association between AEDs and bone disease; a survey found that fewer than one-third of neurologists routinely evaluated AED-treated patients for bone disease, and fewer than 10% prescribed prophylactic calcium and vitamin D. Physicians should counsel patients taking AEDs about good bone health practices, and evaluation of bone health by measuring BMD is warranted after 5 years of AED treatment or before treatment in postmenopausal women.

[Lamotrigine in women with epilepsy. Review of present data]

The manuscript deals with the tolerability of Lamotrigine in women. The recent literature is reviewed with respect to interactions with oral contraceptives, sexuality, infertility, interactions with sex hormones, polycystic ovarian syndrome, adipositas, cosmetic side effects, osteoporosis, pregnancy, breast feeding, and teratogenetic effects. The available data have practical implications for the safe use of Lamotrigine in women.

Medical comorbidities in the treatment of epilepsy

The treatment of epilepsy extends far beyond seizure control. Many comorbidities have a significant impact on the medical management and quality of life of patients with epilepsy. In this review, we examine interactions between epilepsy and some common medical conditions. Psychiatric disorders with a high prevalence in epilepsy include mood disorders, anxiety disorders, and psychosis. Depression is common, psychosis occurs both in direct relation to seizures and interictally, and suicide rates are increased. Changes in sexual function and reduced fertility and marriage rates are described, including a discussion of polycystic ovary syndrome, which is increased in women with epilepsy. The effects of other chronic medical comorbid conditions are reviewed, including the effects of antiepileptic medications on bone health and the impact of renal insufficiency on pharmacological therapy of epilepsy.

Epilepsy: comorbidity in the elderly

Elderly people experience the highest incidence of epilepsy and their clinical mananagement is often challenging, due to a potential increase in the likelihood of adverse treatment events. In addition, concomitant diseases are highly prevalent in this population and elderly patients are likely to be prescribed a number of medications that must be taken concurrently. As a result, the incidence of adverse drug-drug interactions and adverse drug reactions is also extremely high. Thus, the treatment of elderly patients with epilepsy requires careful consideration of any comorbid conditions and concomitant medications. Most adverse events are drug-related and are therefore preventable. It is important to consider these complications when prescribing antiepileptic drug (AED) treatment. An AED with broad-spectrum efficacy, good tolerability and a favourable drug interaction profile (e.g. valproate, gabapentin and lamotrigine) may prevent many unwanted drug interactions and side effects.

The Association Between Antiepileptic Drugs and Bone Disease

A growing body of literature indicates an association between antiepileptic drugs (AEDs) and bone disease, including histologic, radiographic, and biochemical evidence. The AEDs most commonly reported to cause decreased bone mineral density and disorders of bone metabolism are inducers of the cytochrome P450 enzyme system (phenobarbital, phenytoin, carbamazepine, primidone). More recent studies also suggest that valproate, an enzyme inhibitor, causes abnormalities in bone health. Multiple mechanisms have been postulated to support the association; however, no single mechanism explains all the findings. Identifying bone disease in persons with epilepsy receiving AEDs is important, as multiple treatment options are available.

Valproate: past, present, and future

Preclinical studies have been carried out during the past four decades to investigate the different mechanisms of action of valproate (VPA). The mechanisms of VPA which seem to be of clinical importance include increased GABAergic activity, reduction in excitatory neurotransmission, and modification of monoamines. These mechanisms are discussed in relation to the various clinical uses of the drug. VPA is widely used as an antiepileptic drug with a broad spectrum of activity. In patients, VPA possesses efficacy in the treatment of various epileptic seizures such as absence, myoclonic, and generalized tonic-clonic seizures. It is also effective in the treatment of partial seizures with or without secondary generalization and acutely in status epilepticus. The pharmacokinetic aspects of VPA and the frequent drug interactions between VPA and other drugs are discussed. The available methods for the determination of VPA in body fluids are briefly evaluated. At present, investigations and clinical trials are carried out and evaluated to explore the new indications for VPA in other conditions such as in psychiatric disorders, migraine and neuropathic pain. Furthermore, the toxicity of VPA, both regarding commonly occurring side effects and potential idiosyncratic reactions are described. Derivatives of VPA with improved efficacy and tolerability are in development.

Bone mineral density in an outpatient population receiving enzyme-inducing antiepileptic drugs

Antiepileptic drug (AED) use is identified as being associated with increased fracture risk. AEDs commonly associated with osteopathies are inducers of the hepatic cytochrome p450 enzyme system (EIAEDs). We performed a retrospective cross-sectional study assessing bone mineral density (BMD) in an adult outpatient population receiving EIAEDs. Patients were routinely referred for dual-energy X-ray absorptiometry to evaluate BMD. BMD was measured at the femoral neck of hip and lumbar spine. Results were presented as absolute BMD (g/cm(2)), T score, and Z score. T and Z scores were used in this analysis. As a group, those with BMD measurements represent people with intractable epilepsy. There were no statistically significant differences found in the T or Z scores by gender; therefore all analyses combined both men and women. Significant reductions in both T and Z scores were present in men and women <50 and >or=50.

Epilepsy and women's health: family planning, bone health, menopause, and menstrual-related seizures

Epilepsy uniquely affects more than 1 million American women and girls. Health care providers must be aware of the specific concerns and issues regarding the different effects epilepsy has on male and female patients. Epilepsy and antiepileptic drugs substantially affect women's health in the areas of menstruation, contraception, sexual function, pregnancy, menopause, and bone health. Optimal care of women with epilepsy requires collaboration among neurologists, obstetrician-gynecologists, internists, family practitioners, genetic counselors, and nurse educators. This article reviews some areas of concern for women living with epilepsy.

Pharmacological and therapeutic properties of valproate: a summary after 35 years of clinical experience

Thirty-five years since its introduction into clinical use, valproate (valproic acid) has become the most widely prescribed antiepileptic drug (AED) worldwide. Its pharmacological effects involve a variety of mechanisms, including increased gamma-aminobutyric acid (GABA)-ergic transmission, reduced release and/or effects of excitatory amino acids, blockade of voltage-gated sodium channels and modulation of dopaminergic and serotoninergic transmission. Valproate is available in different dosage forms for parenteral and oral use. All available oral formulations are almost completely bioavailable, but they differ in dissolution characteristics and absorption rates. In particular, sustained-release formulations are available that minimise fluctuations in serum drug concentrations during a dosing interval and can therefore be given once or twice daily. Valproic acid is about 90% bound to plasma proteins, and the degree of binding decreases with increasing drug concentration within the clinically occurring range. Valproic acid is extensively metabolised by microsomal glucuronide conjugation, mitochondrial beta-oxidation and cytochrome P450-dependent omega-, (omega-1)- and (omega-2)-oxidation. The elimination half-life is in the order of 9 to 18 hours, but shorter values (5 to 12 hours) are observed in patients comedicated with enzyme-inducing agents such as phenytoin, carbamazepine and barbiturates. Valproate itself is devoid of enzyme-inducing properties, but it has the potential of inhibiting drug metabolism and can increase by this mechanism the plasma concentrations of certain coadministered drugs, including phenobarbital (phenobarbitone), lamotrigine and zidovudine. Valproate is a broad spectrum AED, being effective against all seizure types. In patients with newly diagnosed partial seizures (with or without secondary generalisation) and/or primarily generalised tonic-clonic seizures, the efficacy of valproate is comparable to that of phenytoin, carbamazepine and phenobarbital, although in most comparative trials the tolerability of phenobarbital was inferior to that of the other drugs. Valproate is generally regarded as a first-choice agent for most forms of idiopathic and symptomatic generalised epilepsies. Many of these syndromes are associated with multiple seizure types, including tonic-clonic, myoclonic and absence seizures, and prescription of a broad-spectrum drug such as valproate has clear advantages in this situation. A number of reports have also suggested that intravenous valproate could be of value in the treatment of convulsive and nonconvulsive status epilepticus, but further studies are required to establish in more detail the role of the drug in this indication. The most commonly reported adverse effects of valproate include gastrointestinal disturbances, tremor and bodyweight gain. Other notable adverse effects include encephalopathy symptoms (at times associated with hyperammonaemia), platelet disorders, pancreatitis, liver toxicity (with an overall incidence of 1 in 20,000, but a frequency as high as 1 in 600 or 1 in 800 in high-risk groups such as infants below 2 years of age receiving anticonvulsant polytherapy) and teratogenicity, including a 1 to 3% risk of neural tube defects. Some studies have also suggested that menstrual disorders and certain clinical, ultrasound or endocrine manifestations of reproductive system disorders, including polycystic ovary syndrome, may be more common in women treated with valproate than in those treated with other AEDs. However, the precise relevance of the latter findings remains to be evaluated in large, prospective, randomised studies.