Bone mineral metabolism changes in epileptic children receiving valproic acid

Experimental study on the effects of simvastatin in reversing the femoral metaphyseal defects induced by sodium valproate in normal and ovariectomized rats

Introduction

Long-term treatment with antiepileptic drugs may cause secondary osteoporosis. The present study investigated the influence of simvastatin (SIM) in reversing the effects of valproate on bone defect healing in normal and ovariectomized (OVX) rats.

Methods

Bone defects in femora were established in seven experimental groups of rats: control (vehicle), sodium valproate (SVP; 300 mg/kg/d), SVP plus SIM (25 mg/kg/d), sham control (sham), OVX, OVX SVP and OVX SVP plus SIM. All rats were euthanized at 8 weeks after bone defect creation.

Results

Micro-CT, biomechanical and histological evaluations demonstrated lower bone strength and delayed bone healing in the SVP therapy group compared with the SVP plus SIM therapy group. Biochemical and immunohistochemical results showed that osteocalcin (OCN), collagen I (Col I) and procollagen type I N-terminal propeptide (P1NP) levels decreased, tartrate-resistant acid phosphatase type 5 precursor (TRACP-5b) expression increased, and Dickkopf-1 (DKK-1) and receptor activator of nuclear factor-κ B ligand (RANKL) expression were upregulated in the SVP therapy rats compared with the SVP plus SIM therapy group. Bone loss was exacerbated by OVX, but the effect of SIM in ameliorating bone loss was also more marked in the OVX rats.

Conclusions

This study indicated lower bone strength and delayed healing of bone defects in rats given SVP therapy, especially the OVX SVP treatment group. In contrast, treatment with SIM was effective in enhancing bone strength and promoting bone defect repair and showed significant influence on promoting osteogenesis and inhibiting osteoclastogenesis.

Evaluation of Bone Metabolism in Children Using Antiseizure Drugs: A Single-Center Experience and Review of the Literature

The effect of anti-seizure drugs (ASDs) on bone mineral density (BMD) is a controversial topic. This study investigated the effect of monotherapy and polytherapy drugs separately. Patients with a history of epilepsy treated with the same ASDs for more than 6 months were included in the study. Data regarding patient demographics, biochemical markers related to bone metabolism (calcium, phosphorus, alkaline phosphatase, parathyroid hormone, vitamin D), and BMD with dual-energy X-ray absorptiometry (DXA) were collected and compared. In total, 104 children with epilepsy using valproic acid (VPA), levetiracetam (LEV), carbamazepine (CBZ) alone or in combination and 22 healthy controls were evaluated. The ages of the children (64 boys, 62 girls) ranged between 2 and 17, with a mean of 9.50 ± 4.03 years. BMD or Z-scores did not differ among the monotherapy groups or between them and the polytherapy group. The lowest mean Z-score was in the VPA group but without statistical significance. Alkaline phosphatase levels were significantly higher in the group using CBZ. Calcium levels significantly differed between the groups (p = 0.001). The CBZ and LEV groups had the lowest calcium levels. However, phosphorus and vitamin D measurements did not significantly differ by ASDs used. Unfortunately, low vitamin D levels were evident in all children with epilepsy and even among controls. Physical activity, sun exposure, and calcium intake might be recommended in children treated with ACDs and in combination with additional risk factors monitoring via DXA should be considered. Further studies in a large population are necessary to judge which ASDs are more at risk to reduce bone mineralization than others.

Effect of Daily Vitamin D Supplementation on Serum Vitamin D Levels in Children with Epilepsy Receiving Sodium Valproate Monotherapy: A Randomized, Controlled Trial

OBJECTIVES

To compare the change in serum vitamin D levels and to compare the changes in serum levels of calcium, phosphate, alkaline phosphatase and parathyroid hormone in vitamin D supplemented and unsupplemented groups after 3 mo.

METHODS

In this randomized, parallel group, nonblinded, controlled trial, 40 children, 2-12 y of age with newly diagnosed epilepsy, and vitamin D sufficient status, and started on valproate monotherapy, were randomized into the intervention group (n = 20), which was given daily oral 600 IU vitamin D supplementation, and the control group (n = 20), which was not given any supplementation. Changes in the biochemical parameters was measured in the two groups after 3 mo.

RESULTS

There was a significant reduction in the median (IQR) vitamin D levels in the control group as compared to an increase seen in the intervention group [-6.64 (-8.4, -2.65) vs. 5.66 (1.81, 7.12); p < 0.001]. In the control group, 37.5% children developed vitamin D insufficiency and 12.5% developed deficiency whereas only 5% of the intervention group developed vitamin D insufficiency (p = 0.005). There was a significant decrease in ionized calcium (p = 0.02), increase in serum phosphate (p = 0.02), and alkaline phosphatase level (p = 0.003) in the unsupplemented group as compared to the supplemented group.

CONCLUSION

Vitamin D supplementation can reduce the valproate-associated decline in vitamin D levels and the negative impact on other markers of bone mineral metabolism.

TRIAL REGISTRATION

TCTR20200621002, 19.06.2020, retrospectively registered.

Hypovitaminosis D and risk factors in pediatric epilepsy children

Background

Anti-seizure medication (ASM) treatment is one of the significant risk factors associated with abnormal vitamin D status in epilepsy patients. Multiple studies have shown that adult epilepsy patients can exhibit vitamin D deficiency. However, there are few reports investigating pediatric epilepsy patients. In this study, we aimed to identify risk factors related to hypovitaminosis D in pediatric epilepsy patients in Thailand.

Methods

A cross-sectional retrospective cohort study was conducted in 138 pediatric epilepsy patients who received anticonvulsants from April 2018 to January 2019. Demographic data, seizure types, puberty status, physical activity, duration, and types of anti-seizure medications were analyzed. Patients with abnormal liver function, abnormal renal function, and who received vitamin D supplements or ketogenic diet containing vitamin D were excluded. Levels of serum vitamin D (25(OH)D) were measured.

Results

All 138 subjects were enrolled, the age ranged from 1.04 – 19.96 years; (mean = 9.65 ± 5.09), the mean serum 25(OH) D level was 26.56 ± 9.67 ng/ml. The prevalence of vitamin D deficiency was 23.2% and insufficiency was 47.8% respectively. Two risk factors—puberty status (OR 5.43, 95% CI 1.879-15.67) and non-enzyme-inhibiting ASMs therapy (OR 3.58, 95% CI 1.117-11.46)—were significantly associated with hypovitaminosis D, as shown by multivariate analyses.

Conclusions

Our study reports the high prevalence of hypovitaminosis D in pediatric epilepsy patients in Thailand despite being located in the tropical zone. These findings can guide clinicians to measure vitamin D status in pediatric epilepsy patients particularly when they reach puberty and/or are using non-enzyme-inhibiting ASMs therapy. Early detection of vitamin D status and prompt vitamin D supplementation can prevent fractures and osteoporosis later in life.

Trial registration

TCTR20210215005 (http://www.clinicaltrials.in.th/).

Targeting Histone Modifications in Bone and Lung Metastatic Cancers

PURPOSE OF REVIEW

Breast cancer frequently metastasizes to the bone and lung, but the ability to treat metastatic tumor cells remains a pressing clinical challenge. Histone deacetylases (HDACs) and histone acetyltransferases (HATs) have emerged as promising targets since these enzymes are aberrantly expressed in numerous cancers and regulate the expression of genes that drive tumorigenesis and metastasis. This review focuses on the abnormal expression of histone-modifying enzymes in cancers that have a high tropism for the bone and lung and explores the clinical use of histone deacetylase inhibitors for the treatment and prevention of metastasis to these sites.

RECENT FINDINGS

Preclinical studies have demonstrated that the role for HDACs is highly dependent on tumor type and stage of disease progression. HDAC inhibitors can induce apoptosis, senescence, cell differentiation, and tumor dormancy genes and inhibit angiogenesis, making these promising therapeutics for the treatment of metastatic disease. HDAC inhibitors are already FDA approved for hematologic malignancies and are in clinical trials with standard-of-care chemotherapies and targeted agents for several solid tumors, including cases of metastatic disease. However, these drugs can negatively impact bone homeostasis. Although HDAC inhibitors are not currently administered for the treatment of bone and lung metastatic disease, preclinical studies have shown that these drugs can reduce distant metastasis by targeting molecular factors and signaling pathways that drive tumor cell dissemination to these sites. Thus, HDAC inhibitors in combination with bone protective therapies may be beneficial in the treatment of bone metastatic cancers.

The effects of antiepileptic drugs on bone health: A systematic review

PURPOSE

Epilepsy may be treated with antiepileptic drugs (AEDs), which have been reported to decrease bone mineral density (BMD). Current data is conflicting and variable, and little is known with regard to how duration of AED use or specific AEDs, such as CYP-450 enzyme-inducing (EIAEDs) versus non-enzyme inducing (NEIAEDs) drugs affect BMD. We sought to systematically review BMD changes due to AED use to identify trends in reporting.

METHODS

A literature search via Medline (PubMed), EMBASE, and Cochrane databases was performed. Peer-reviewed articles were identified that reported on BMD measurements in conjunction with AEDs.

RESULTS

Twenty-six studies met inclusion criteria. Long-term therapy was shown across multiple, well-controlled studies to have the most significant BMD loss. Carbamazepine had the most frequent reporting of unfavorable effects on bone health and Lamotrigine seemed to show the most bone-protective qualities. Serum biochemical markers of bone turnover did not significantly correlate with measured BMD changes.

CONCLUSION

The present study provides evidence that long-term AED therapy is the most significant risk factor for BMD loss. Furthermore, there was little compelling evidence to support that EIAEDs, as a class, were more harmful to bone than NEIAEDs, which has been previously suggested in multiple studies. Early clinical concern for significant loss of BMD may not be warranted as lower BMD was less likely to be observed during the initial years of AED therapy. Furthermore, serum markers of bone turnover are not clinically reliable in assessing BMD changes in patients taking AEDs.

Valproic Acid Impacts the Growth of Growth Plate Chondrocytes

A range of bone abnormalities including short stature have been reported to be associated with the use of antiepileptic drugs (AEDs) in children. Exactly how AEDs impact skeletal growth, however, is not clear. In the present study, rat growth plate chondrocytes were cultured to study the effects of AEDs, including valproic acid (VPA), oxcarbazepine (OXA), levetiracetam (LEV), lamotrigine (LTG), and topiramate (TPM) on the skeletal growth. VPA markedly reduced the number of chondrocytes by apoptosiswhile other AEDs had no effect. The apoptosis associated noncleaved and cleaved caspase 3, and caspases were increased by exposure to VPA, which up-regulated cyclooxygenase 2 (COX-2) mRNA and protein levels likely through histone acetylation. The COX-2 inhibitor NS-398 attenuated the effects of VPA up-regulating COX-2 expression and decreased VPA-induced caspase 3 expression. The use of VPA in children should be closely monitored or replaced, where appropriate, by AEDs which do not apparently affect the growth plate chondrocytes.

Effects of valproic acid on skeletal metabolism in children with epilepsy: a systematic evaluation and meta-analysis based on 14 studies

BACKGROUND

Previous studies have reported that long-term use of valproic acid can cause changes in bone metabolism in children. We conducted this meta-analysis to determine the effects of valproic acid on bone metabolism and bone mineral density (BMD) in children with epilepsy.

METHODS

Studies were searched from the databases of PubMed, Embase, Ovid, Cochrance Library, Springer Link and Web of Science. The effects of valproic acid on bone metabolism indicators and BMD were assessed through calculating the standardized mean difference (SMD) with 95% confidence interval (CI).

RESULTS

Fourteen studies with 987 individuals were included in this analysis. The long-term use of valproic acid did not affect the levels of serum calcium (p = 0.99), phosphorus (p = 0.28), ALP (p = 0.76), PTH (p = 0.36) and osteocalcin (p = 0.72), but it led to a decrease in 25-OH-VitD (p = 0.01) and BMD (p = 0.002 for the vertebra; p = 0.004 for the femur) in treating children with epilepsy.

CONCLUSION

Long-term use of valproic acid in treating children with epilepsy can lead to a reduction in 25-OH-VitD and BMD. Measurements of 25-OH-VitD and BMD should be performed regularly in children taking the drug to detect early osteopenia caused by the drug.

Bone health in pediatric patients with neurological disorders

Patients with neurological disorders are at high risk of developing osteoporosis, as they possess multiple risk factors leading to low bone mineral density. Such factors include inactivity, decreased exposure to sunlight, poor nutrition, and the use of medication or treatment that can cause lower bone mineral density such as antiepileptic drugs, ketogenic diet, and glucocorticoids. In this article, mechanisms involved in altered bone health in children with neurological disorders and management for patients with epilepsy, cerebral palsy, and Duchenne muscular dystrophy regarding bone health are reviewed.

Integrative regulation of physiology by histone deacetylase 3

Cell-type-specific gene expression is physiologically modulated by the binding of transcription factors to genomic enhancer sequences, to which chromatin modifiers such as histone deacetylases (HDACs) are recruited. Drugs that inhibit HDACs are in clinical use but lack specificity. HDAC3 is a stoichiometric component of nuclear receptor co-repressor complexes whose enzymatic activity depends on this interaction. HDAC3 is required for many aspects of mammalian development and physiology, for example, for controlling metabolism and circadian rhythms. In this Review, we discuss the mechanisms by which HDAC3 regulates cell type-specific enhancers, the structure of HDAC3 and its function as part of nuclear receptor co-repressors, its enzymatic activity and its post-translational modifications. We then discuss the plethora of tissue-specific physiological functions of HDAC3.

Bone Mineral Density Loss in People With Epilepsy Taking Valproate as a Monotherapy: A Systematic Review and Meta-Analysis

Objective: Data on changes in bone mineral density (BMD) from valproate (VPA) therapy are ambiguous and conflicting. Thus, the aim of this study was to systematically review the existing data and carry out a meta-analysis to investigate the effect of VPA as a monotherapy on BMD in people with epilepsy (PWE). Methods: We systematically searched PubMed, EMBASE, and MEDLINE for eligible studies. We calculated the standardized mean difference (SMD) with 95% confidence interval (CI) to investigate the statistical power of the association between VPA treatment and BMD. Results: Nineteen studies were included in this systematic review and meta-analysis. We found that BMD was lower in the VPA group than in the control group (SMD: -0.44; 95% CI: -0.65 to -0.22). A significant association was found in adult patients (SMD: -0.57; 95% CI: -0.88 to -0.26; I 2 = 69.8%) and pediatric patients (SMD: -0.32; 95% CI: -0.60 to -0.03; I 2 = 67.8%) by subgroup analysis. This study indicated that BMD was significantly lower in patients treated for more than 36 months than in controls (SMD: -0.52; 95% CI: -0.76 to -0.27; I 2 = 61.8%). However, a significant difference was not found between patients who were treated for less than 36 months and controls (SMD: -0.36; 95% CI: -0.72 to 0.01; I 2 = 74.8%). Conclusion and significance: The present study provided evidence that VPA treatment was significantly associated with BMD loss in PWE. Thus, for patients at a high risk of osteoporosis and fracture, especially for patients who need long-term treatment, VPA may not be a good choice.

Effects of valproic acid on bone mineral density and bone metabolism: A meta-analysis

PURPOSE

Numerous studies have shown that the risk of fracture is increased by long-term antiepileptic drugs (AEDs). Valproic acid (VPA) is one of the most commonly used AEDs. In this meta-analysis, we aimed to assess the effects of VPA on bone mineral density (BMD) and bone metabolism.

METHODS

PubMed, Embase, Cochrane and Web of Science databases were searched from inception to January 2019 for articles focusing on the effects of VPA on BMD and bone metabolism in adults or children. A meta-analysis was performed using RevMan 5. 3 software.

RESULTS

18 studies were included in the meta-analysis. The BMD of lumber spine (MD= -0.06, 95%CI: -0.09 to -0.03, P < 0.0001) and femoral neck (MD= -0.05, 95% CI= -0.08 to -0.01, P = 0.02) was markedly decreased in the VPA group compared to healthy controls. Serum bone-specific alkaline phosphatase (BALP) level (SMD = 0.85, 95% CI: 0.30-1.40, P = 0.002) was notably increased in the VPA group compared to healthy groups. In the child group, the serum parathyroid hormone (PTH) level was higher than in healthy groups (SMD= -0.22, 95% CI: -0.40 to -0.04, P = 0.02); besides, the serum 25-hydroxy vitamin D3 (25(OH)D3) level was decreased (SMD= -0.22, 95% CI: -0.40 to -0.04, P = 0.02), while no significant alteration of these parameters was noted in the adult VPA group (P ≥ 0.05).

CONCLUSIONS

VPA may reduce the BMD of lumbar spine and femoral neck in patients with epilepsy while increasing the serum BALP level. Serum PTH level are increased and serum 25(OH)D3 level decreased in children with epilepsy treated with VPA. These parameters were unaltered in adults.

How safe is bone health in patients on newer or enzyme inhibitor antiepileptic drugs?

BACKGROUND

Data on the effect of enzyme inhibitors and newer anti-epileptic drugs (AEDs) on bone health is limited with conflicting results.

AIM

We compared the effects on bone health of patients exposed to enzyme inducer versus enzyme inhibitor AEDs and newer versus older AEDs.

METHODS

We prospectively studied 51 patients on AEDs for more than two years and equal age and sex matched controls from March 2017 to September 2018. Biochemical bone mineral markers and bone mineral density (BMD) were measured and analysed between patients versus controls and between various sub-groups based on enzymatic effect, generation and number of AEDs.

RESULTS

Of 51 patients,11(21.5%) had osteopenia and 3(5.9%) had osteoporosis. T-score (-0.75 ± 1.22 versus 0.004 ± 1.0, p < .001) and Z-score at femur neck (-0.38 ± 1.08 versus0.002 ± 0.81, p < .001) were found to be significantly lower in patients compared to controls. Relative risk for low BMD was higher in patients on polytherapy compared to monotherapy (RR = 1.37,CI = 0.69-2.74).Higher relative risk for low BMD was noted with; clobazam (RR = 1.51,CI = 0.82-2.78), oxcarbazepine (RR = 1.33,CI = 0.68-2.59), phenobarbitone (RR = 1.31,CI = 0.26-6.7) and leviteracetam (RR = 1.18,CI = 0.45-3.06) mono or polytherapy and valproate monotherapy (RR = 3.5,CI = 1.09-11.29). No significant difference was noted with regards to mean dosage or metabolic or radiological markers of bone health between patients on enzyme inducer versus inhibitors and newer versus older AEDs. A significant negative correlation was found between cumulative drug load and femur T-score (r2 = -0.27, p = .04).

CONCLUSION

Bone health in epilepsy is adversely affected by chronic exposure to AEDs; irrespective of the enzymatic effect or generation of AEDs. Complex pharmacodynamic mechanisms of AEDs as well as pharmacokinetic interactions between various AED polytherapies affects bone health.

Vitamin D supplementation and bone markers in ambulatory children on long-term valproic acid therapy. A prospective interventional study

PURPOSE

Our aim was to investigate any adverse effects of long-term valproic acid (VPA) therapy on bone biochemical markers in ambulatory children and adolescents with epilepsy, and the possible benefits of vitamin D supplementation on the same markers.

METHODS

In this single center, the prospective interventional study levels of 25-hydroxyvitamin D (25OHD) and the bone turnover indices of Crosslaps (CTX), total alkaline phosphatase (tALP), osteoprotegerin (OPG), and the receptor activator for nuclear factor kB (RANK) ligand (sRANKL) were assessed before and after one year of vitamin D intake (400 IU/d) and were compared with those of clinically healthy controls. Fifty-four ambulatory children with mean (±standard deviation [SD]) age 9.0 ± 4.5 yrs on VPA (200-1200 mg/d) long-term monotherapy (mean: 3.2 ± 2.6 yrs) were studied, before and after a year's vitamin D intake (400 IU/d).

RESULTS

Nearly half of the cases were vitamin D insufficient/deficient with mean levels 23.1 ± 12.8 vs 31.8 ± 16.2 ng/mL of controls (p = 0.004) and after the year of vitamin D intake increased to 43.2 ± 21.7 ng/mL (p < 0.0001). In parallel, serum CTX and tALP had a decreasing trend approaching control levels but OPG and sRANKL did not change and were not different from controls. However, after vitamin D intake, a positive correlation was seen between 25OHD and OPG but not before.

CONCLUSIONS

The findings imply a higher bone turnover in the young patients on long-term VPA therapy that decreased after vitamin D intake.

Densidad mineral ósea e indicadores bioquímicos y hormonales en niños con parálisis cerebral cuadripléjica

Introduction: children with cerebral palsy (CP) have multiple risk factors for low bone mineral density or osteoporosis. Objective: to explore the association between bone mineral density (BMD) and biochemical and hormonal indicators of bone metabolism in children with quadriplegic cerebral palsy (CP). Methods: a cross-sectional analytical study included 59 participants from six to 18 years of age with quadriplegic CP. Serum concentrations of calcium, phosphorus, 25OHD metabolite, parathyroid hormone (PTH), alkaline phosphatase, and thyroid hormones were determined using standardized methods. The BMD measurement was obtained from the lumbar spine expressed in g/cm2 and Z-score. Unpaired Student's t-test, Chi-square test, odds ratio and Pearson's correlation were performed. Results: participants with CP and malnutrition had lower serum concentrations of calcium, phosphorus and alkaline phosphatase. Those who had low BMD showed lower serum concentrations of calcium, phosphorus and alkaline phosphatase. Most participants with low and normal BMD had vitamin D deficiency (27.1% and 10%) and insufficiency (35.4% and 30%), respectively. There was a significant correlation between BMD and serum concentrations of calcium, phosphorus, alkaline phosphatase, vitamin D and thyroid-stimulating hormone (TSH). There were no differences in the biochemical and hormonal indicators by level of gross motor function, use of anticonvulsants and oral versus enteral feeding method. Conclusion: malnutrition and alteration of vitamin D nutritional status were associated with low BMD and alterations of biochemical indicators of bone metabolism in pediatric patients with quadriplegic CP. The relationship between BMD and biochemical indicators of bone metabolism in children with quadriplegic CP was also demonstrated.

The footprints of mitochondrial impairment and cellular energy crisis in the pathogenesis of xenobiotics-induced nephrotoxicity, serum electrolytes imbalance, and Fanconi's syndrome: A comprehensive review

Fanconi's Syndrome (FS) is a disorder characterized by impaired renal proximal tubule function. FS is associated with a vast defect in the renal reabsorption of several chemicals. Inherited and/or acquired conditions seem to be connected with FS. Several xenobiotics including many pharmaceuticals are capable of inducing FS and nephrotoxicity. Although the pathological state of FS is well described, the exact underlying etiology and cellular mechanism(s) of xenobiotics-induced nephrotoxicity, serum electrolytes imbalance, and FS are not elucidated. Constant and high dependence of the renal reabsorption process to energy (ATP) makes mitochondrial dysfunction as a pivotal mechanism which could be involved in the pathogenesis of FS. The current review focuses on the footprints of mitochondrial impairment in the etiology of xenobiotics-induced FS. Moreover, the importance of mitochondria protecting agents and their preventive/therapeutic capability against FS is highlighted. The information collected in this review may provide significant clues to new therapeutic interventions aimed at minimizing xenobiotics-induced renal injury, serum electrolytes imbalance, and FS.

Bone mineral density loss in ambulatory children with epilepsy in spite of using supplemental vitamin D in Southern Iran: a case-control study

Epilepsy might have adverse effect on bone density due to underlying disease, drugs, vitamin D deficiency, immobilization and malnutrition. We investigated the bone mineral density in ambulatory vitamin-D supplemented children with epilepsy. This case-control study was conducted on 90 epileptic children aged 11.4 ± 3.3 years, and age and gender matched controls in pediatric neurology clinics of Shiraz, in Southern Iran, 2016. Anthropometric measurements, puberty, sun exposure, physical activity and biochemical variables were assessed. Bone mineral density was evaluated by dual-energy X-ray absorptiometry method. Data were analyzed by SPSS.v21. Prevalence of low bone mass in femur was more in patients (27%) than the controls (9%) (P value = 0.002). Age, weight Z score and height Z score were the most significant associated factors on lumbar BMD, BMAD, and femur BMD. Seizure duration and how it responded to anticonvulsants were the most associated factors with both lumbar and femur bone density. Sodium valproate and carbomazepin usage had negative association with lumbar Z score (beta = - 0.216, P = 0.017 and beta = - 0.336, P = 0.027, respectively). We hypothesized that epilepsy per se could affect bone density by an unknown pathophysiology, which was independent from vitamin D deficiency, effects of anticonvulsant and physical activity.

Regulation of Osteoclast Differentiation and Skeletal Maintenance by Histone Deacetylases

Bone is a dynamic tissue that must respond to developmental, repair, and remodeling cues in a rapid manner with changes in gene expression. Carefully-coordinated cycles of bone resorption and formation are essential for healthy skeletal growth and maintenance. Osteoclasts are large, multinucleated cells that are responsible for breaking down bone by secreting acids to dissolve the bone mineral and proteolytic enzymes that degrade the bone extracellular matrix. Increased osteoclast activity has a severe impact on skeletal health, and therefore, osteoclasts represent an important therapeutic target in skeletal diseases, such as osteoporosis. Progression from multipotent progenitors into specialized, terminally-differentiated cells involves carefully-regulated patterns of gene expression to control lineage specification and emergence of the cellular phenotype. This process requires coordinated action of transcription factors with co-activators and co-repressors to bring about proper activation and inhibition of gene expression. Histone deacetylases (HDACs) are an important group of transcriptional co-repressors best known for reducing gene expression via removal of acetyl modifications from histones at HDAC target genes. This review will cover the progress that has been made recently to understand the role of HDACs and their targets in regulating osteoclast differentiation and activity and, thus, serve as potential therapeutic target.

Differential effects of antiepileptic drugs on human bone cells

Antiepileptic drugs (AED) have been associated to in vivo deleterious consequences in bone tissue. The present work aimed to characterize the cellular and molecular effects of five different AED on human osteoclastogenesis and osteblastogenesis. It was observed that the different drugs had the ability to differentially modulate both processes, in a way dependent on the identity and dose of the AED. Shortly, valproic acid stimulated either osteoclastogenesis and osteoblastogenesis, whereas carbamazepine, gabapentin, and lamotrigine revealed an opposite behavior; topiramate elicited a decrease of osteoclast development and an increase in osteoblast differentiation. This is the first report describing the direct effects of different AED on human primary bone cells, which is a very important issue, because these drugs are usually consumed in long-term therapeutics, with acknowledged in vivo effects in bone tissue.

Levetiracetam and lamotrigine effects as mono- and polytherapy on bone mineral density in epileptic patients

OBJECTIVE

The purpose of this study was to determine the effect of lamotrigine (LTG) and levetiracetam (LEV) as mono- and polytherapy on biochemical markers of bone turnover and bone mineral density in Egyptian adult patients with epilepsy.

METHODS

Forty-eight patients were divided into four groups: two received monotherapy of either LTG or LEV, and the other two groups received polytherapy comprising (valproate [VPA] + LTG or VPA + LEV). Thirty matched healthy participants were included in the study. Participants completed a nutritional and physical activity questionnaire. Biochemical markers of bone and mineral metabolism and bone mineral density of the lumbar spine were measured at baseline and at six months.

RESULTS

In the LEV monotherapy group, the bone formation markers showed a significant decrease in serum alkaline phosphatase and serum osteocalcin levels while the bone resorption marker showed a significant increase in urinary deoxypyridinoline levels. After six months of treatment, bone mineral density showed a significant decrease in all treated groups, while among monotherapy groups, this significant decrease was more prevalent in the LEV monotherapy group compared with the LTG monotherapy group. Furthermore, there was significant negative correlation between urinary deoxypyridinoline levels and bone mineral density in the LEV monotherapy group.

CONCLUSION

Using new generation antiepileptics, LEV monotherapies and polytherapy showed harmful effects on bone but LTG did not.

Evaluation of bone health among epileptic patients using biochemical markers and DEXA scan: an Egyptian study

BACKGROUND

An association between antiepileptic drugs, low bone mineral density (BMD), fractures, and abnormalities in bone metabolism has been suggested for a longer period, although conclusive evidence has not been reported.

METHODS

Thirty epileptic patients and 30 matched healthy subjects participated in the study. Measurements of serum levels of calcium, phosphorus, vitamin D, parathormone, and alkaline phosphatase were done for included subjects. Dual-energy X-ray absorptiometry (DEXA) scan was also performed.

RESULTS

Serum calcium, phosphorus, and vitamin D were significantly lower, whereas serum parathormone and alkaline phosphatase were significantly higher in epileptic patients compared to control subjects. Bone mineral density (BMD) abnormalities were detected in 22 patients (73.4%). A statistically significant difference in DEXA scan measurements at different regions was detected between epileptic patients and control subjects. Epileptic patients receiving enzyme inducer antiepileptic drugs (AEDs) had significantly lower serum (calcium, phosphorous, and vitamin D) and lower BMD values compared to those receiving enzyme inhibitors. Results of BMD were positively correlated with serum calcium, phosphorous, and vitamin D, while negatively correlated with serum alkaline phosphatase and duration of therapy.

CONCLUSIONS

Abnormal bone health is common in epileptic patients. These abnormalities may be attributed to prolonged intake of AEDs especially enzyme inducers.

Decreased bone density induced by antiepileptic drugs can cause accelerated orthodontic tooth movement in male Wistar rats

PURPOSE

The aim of the present study was to evaluate the effect of the carbamazepine and valproic acid on orthodontic tooth movement in male Wistar rats.

METHODS

Evaluation of tooth movement after 21 days of drugs infusion was carried out by feeler gauge. Bone densitometry on lateral cephalograms was conducted on days 1 and 21. After dissection of the maxillae, histologic parameters were evaluated.

RESULTS

Orthodontic tooth movement was accelerated in experimental groups rather than controls. Optical density was significantly increased in these groups. In histologic sections, mesioapical portion of the PDL (Periodontal Ligament) was wider in experimental groups. Also, distoapical portion of the PDL was wider only in valproic acid group.

CONCLUSION

Valproic acid and carbamazepine can decrease the bone density which may induce the accelerated orthodontic tooth movement in rats.

Dispensability of Annual Laboratory Follow-Up After More than 2 Years of Valproic Acid Use: A Systematic Review

BACKGROUND

The necessity of annual laboratory follow-up in patients treated with valproic acid (VPA) is controversial.

OBJECTIVE

We investigated the need for annual laboratory follow-up of liver enzymes, electrolytes, and full blood count (FBC) in patients treated with VPA.

PATIENTS AND METHODS

A systematic search in Evidence-Based Medicine Reviews (EBMR), MEDLINE, and EMBASE was undertaken in December 2016 to identify all published articles investigating or citing valproic acid, liver function disorders, electrolyte disorders, and FBC deviations.

RESULTS

This review included 108 articles. As the number of participants and duration of the study was not adequate in most studies to detect rare adverse events, studies did not demonstrate a clear prevalence of hepatotoxicity. While a transient increase of transaminases is common and seldom harmful, severe hepatotoxicity is a rare phenomenon and is not prevented by routine laboratory monitoring. VPA had no relevant effect on serum calcium, sodium, potassium, and albumin. The prevalence of FBC varied from 0.6 to 27.8%, occurred mostly in the first 2 years of therapy, and was usually asymptomatic.

CONCLUSIONS

Long-term monitoring in VPA treatment is only necessary when there have been dose adjustments, co-medication switches, or co-morbidity. In uncomplicated cases, annual laboratory follow-up may be discontinued after 2 years of VPA treatment. Encouraging patients to be vigilant is more effective in the detection of hepatotoxicity than laboratory testing. Follow-up of FBC at 3-6 months, 1 year, and 2 years after start or after a dose increase of VPA or interacting medication is sufficient.

Histone Deacetylases in Cartilage Homeostasis and Osteoarthritis

The involvement of the epigenome in complex diseases is becoming increasingly clear and more feasible to study due to new genomic and computational technologies. Moreover, therapies altering the activities of proteins that modify and interpret the epigenome are available to treat cancers and neurological disorders. Many additional uses have been proposed for these drugs based on promising preclinical results, including in arthritis models. Understanding the effects of epigenomic drugs on the skeleton is of interest because of its importance in maintaining overall health and fitness. In this review, we summarize ongoing advancements in how one class of epigenetic modifiers, histone deacetylases (Hdacs), controls normal cartilage development and homeostasis, as well as recent work aimed at understanding the alterations in the expression and activities of these enzymes in osteoarthritis (OA). We also review recent studies utilizing Hdac inhibitors and discuss the potential therapeutic benefits and limitations of these drugs for preventing cartilage destruction in OA.

The Impact of Anti-Epileptic Drugs on Growth and Bone Metabolism

Epilepsy is a common neurological disorder worldwide and anti-epileptic drugs (AEDs) are always the first choice for treatment. However, more than 50% of patients with epilepsy who take AEDs have reported bone abnormalities. Cytochrome P450 (CYP450) isoenzymes are induced by AEDs, especially the classical AEDs, such as benzodiazepines (BZDs), carbamazepine (CBZ), phenytoin (PT), phenobarbital (PB), and valproic acid (VPA). The induction of CYP450 isoenzymes may cause vitamin D deficiency, hypocalcemia, increased fracture risks, and altered bone turnover, leading to impaired bone mineral density (BMD). Newer AEDs, such as levetiracetam (LEV), oxcarbazepine (OXC), lamotrigine (LTG), topiramate (TPM), gabapentin (GP), and vigabatrin (VB) have broader spectra, and are safer and better tolerated than the classical AEDs. The effects of AEDs on bone health are controversial. This review focuses on the impact of AEDs on growth and bone metabolism and emphasizes the need for caution and timely withdrawal of these medications to avoid serious disabilities.

Histone Deacetylases in Bone Development and Skeletal Disorders

Histone deacetylases (Hdacs) are conserved enzymes that remove acetyl groups from lysine side chains in histones and other proteins. Eleven of the 18 Hdacs encoded by the human and mouse genomes depend on Zn(2+) for enzymatic activity, while the other 7, the sirtuins (Sirts), require NAD2(+). Collectively, Hdacs and Sirts regulate numerous cellular and mitochondrial processes including gene transcription, DNA repair, protein stability, cytoskeletal dynamics, and signaling pathways to affect both development and aging. Of clinical relevance, Hdacs inhibitors are United States Food and Drug Administration-approved cancer therapeutics and are candidate therapies for other common diseases including arthritis, diabetes, epilepsy, heart disease, HIV infection, neurodegeneration, and numerous aging-related disorders. Hdacs and Sirts influence skeletal development, maintenance of mineral density and bone strength by affecting intramembranous and endochondral ossification, as well as bone resorption. With few exceptions, inhibition of Hdac or Sirt activity though either loss-of-function mutations or prolonged chemical inhibition has negative and/or toxic effects on skeletal development and bone mineral density. Specifically, Hdac/Sirt suppression causes abnormalities in physiological development such as craniofacial dimorphisms, short stature, and bone fragility that are associated with several human syndromes or diseases. In contrast, activation of Sirts may protect the skeleton from aging and immobilization-related bone loss. This knowledge may prolong healthspan and prevent adverse events caused by epigenetic therapies that are entering the clinical realm at an unprecedented rate. In this review, we summarize the general properties of Hdacs/Sirts and the research that has revealed their essential functions in bone forming cells (e.g., osteoblasts and chondrocytes) and bone resorbing osteoclasts. Finally, we offer predictions on future research in this area and the utility of this knowledge for orthopedic applications and bone tissue engineering.

Effects of antiepileptic drugs on bone mineral density and bone metabolism in children: a meta-analysis

OBJECTIVE

The aim of our meta-analysis was to assess the effects of antiepileptic drugs on bone mineral density and bone metabolism in epileptic children.

METHODS

Searches of PubMed and Web of Science were undertaken to identify studies evaluating the association between antiepileptic drugs and bone mineral density and bone metabolism.

RESULTS

A total of 22 studies with 1492 subjects were included in our research. We identified: (1) a reduction in bone mineral density at lumbar spine (standardized mean difference (SMD)=-0.30, 95% confidence interval (CI) [-0.61, -0.05]), trochanter (mean difference (MD)=-0.07, 95% CI [-0.10, -0.05]), femoral neck (MD=-0.05, 95% CI [-0.09, -0.02]), and total body bone mineral density (MD=-0.33, 95% CI [-0.51, -0.15]); (2) a reduction in 25-hydroxyvitamin D (MD=-3.37, 95% CI [-5.94, -0.80]) and an increase in serum alkaline phosphatase (SMD=0.71, 95% CI [0.38, 1.05]); (3) no significant changes in serum parathyroid hormone, calcium, or phosphorus.

CONCLUSIONS

Our meta-analysis suggests that treatment with antiepileptic drugs may be associated with decreased bone mineral density in epileptic children.

Effects of antiepileptic drugs on bone health and growth potential in children with epilepsy

BACKGROUND

Bone health may be impaired in children with epilepsy.

OBJECTIVES

Our objective was to characterize bone mineral density (BMD) and bone growth in children receiving antiepileptic drugs (AEDs) and to assess the effects of co-morbidity, vitamin D deficiency, and type of drugs used.

DATA SOURCES

Data were sourced from PubMed, Embase, and Web of Science.

ELIGIBILITY CRITERIA

Cross-sectional, cohort, case-control, or randomized controlled trials reporting BMD or parameters of bone growth.

PARTICIPANTS

Children with epilepsy compared with controls.

INTERVENTIONS

AEDS or ketogenic diet.

STUDY APPRAISAL

The studies were evaluated by one author.

SYNTHESIS METHODS

Studies were categorized as reporting reduced BMD or not at any skeletal site as outcome. A logistic regression was performed for age, percent boys, study design, type of AED, co-morbidity or not, and signs of vitamin D deficiency/osteomalacia or not.

RESULTS

Carbamazepine and valproate were analyzed as monotherapy in 11 studies, and for both drugs a limited decrease in BMD seemed present. For oxcarbazepine, levetiracetam, phenytoin, phenobarbital, and topiramate, only one study with monotherapy was found for each drug, none of which reported decreased bone density. Polytherapy with AEDs seemed to be associated with a larger decrease in bone density than was monotherapy. Although few studies were available on bone growth, these did indicate that bone growth may be impaired among users of AEDs. Ketogenic diet may be associated with decreased bone density. The main determinant of normal BMD was absence of vitamin D deficiency/osteomalacia.

LIMITATIONS

The studies differed in skeletal sites studied and most were cross-sectional. No head-to-head comparisons of AEDs were performed. Children treated with polytherapy or ketogenic diet may have more complicated and severe disease than those treated with monotherapy. The underlying cause of epilepsy and vitamin D deficiency may contribute to impaired bone growth and density.

CONCLUSIONS

Reduced bone density, impaired bone growth, and vitamin D deficiency may be seen in children treated with drugs against epilepsy.

IMPLICATIONS

Measures to correct vitamin D deficiency, calcium intake should be taken.

Epilepsy treatment by sacrificing vitamin D

Epilepsy is one of the most common neurologic disorders in childhood that often requires long term treatment with antiepileptic drugs. Both antiepileptic treatment and the comorbidities associated with epilepsy have a negative impact on bone health in growing children. Given the fact that vitamin D deficiency is a major public health problem worldwide, clinicians caring for children with chronic diseases should be aware of effects of the medication on the bone metabolism. Yet, vitamin D deficiency due to antiepileptic treatment is an overlooked issue among neurologists. In this review, we briefly describe vitamin D metabolism and the effect of vitamin D in the brain. We also discuss the literature in terms of vitamin D deficiency and antiepileptic treatment in the pediatric population.

Antiepileptic drugs and high prevalence of low bone mineral density in a group of inpatients with chronic epilepsy

PURPOSE

Long-term antiepileptic drug use is associated with low bone mineral density (BMD), fractures and abnormalities in bone metabolism. We aimed at determining the prevalence of bone mineral disorders in patients with refractory epilepsy treated with antiepileptic drugs.

METHODS

A cross-sectional survey was conducted in adult patients (n = 205) from a residential unit of a tertiary epilepsy centre. Screening for bone mineral disorders was performed with dual-energy X-ray absorptiometry (DXA) scan of spine and hip (including bone mineral density and vertebral fracture assessment) and laboratory measurements. Patient information regarding demography, epilepsy characteristics and medication use was recorded. Based on DXA T-scores, prevalence of bone mineral disorders (osteopenia and osteoporosis) was calculated. Correlations between DXA T-scores and epilepsy parameters were explored.

RESULTS

Of the 205 patients, there were 10 dropouts. 80% (n = 156/195) of the patients had low BMD: 48.2% had osteopenia and 31.8% had osteoporosis. Of those having low BMD, 51.9% (n = 81/195) was between 18 and 50 years. The T-score of the femoral neck correlated significantly with total duration of epilepsy, cumulative drug load and history of fractures. Linear regression analysis showed that of the epilepsy-related parameters, only cumulative drug load significantly predicted low femoral neck T-score (P = 0.001).

CONCLUSION

In this high-risk population, we obtained a very high prevalence of 80% of low BMD. Both men and women were affected as well as patients <50 years of age. This study illustrates the magnitude of the problem of bone mineral disorders in chronic epilepsy.

Antiepileptic drugs and bone metabolism in children: data from 128 patients

There are conflicting results concerning bone metabolism in children receiving antiepileptic medication, with data concentrating on neurologically impaired patients. We performed a multicenter cross-sectional study in otherwise healthy children who received monotherapy with valproic acid, oxcarbazepine, lamotrigine, sulthiame, levetiracetam, or topiramate for at least 6 months. Data on calcium, phosphorus, alkaline phosphatase, 25-OH vitamin D, and parathormone were collected. Among 128 patients, 24.4% had hypocalcemia, 25.4% hypophosphatemia, and 13.3% (n = 17) 25-OH vitamin D levels <10 ng/mL. All patients were clinically asymptomatic. Mean calcium concentrations were found to be significantly lower among the study population (2.41 mmol/L) compared with healthy controls (2.53 mmol/L). Lowest mean concentration was observed in patients treated with sulthiame followed by oxcarbazepine and valproic acid. No influence of calcium intake or therapy on bone metabolism was noted. Effects on bone metabolism of anticonvulsive monotherapy are not restricted to neurologically impaired children but also affect otherwise healthy children.

Vitamin D deficiency in children with epilepsy: Do we need to detect and treat it?

Children and adolescents treated with antiepileptic drugs are known to have problems with bone metabolism, bone mineral density loss, and 2-3 times the fracture risk of healthy controls. We reviewed the literature regarding bone mineral density in children with epilepsy and vitamin D therapy in children treated with anti-epileptic drugs. Studies of bone mineral density markers in children with epilepsy have mostly found little significant difference in bone mineral density markers in children with epilepsy. They have been limited by small sample size and many of the studies have not corrected for confounding factors such as comorbidities, mobility, nutrition, and obesity. Studies of vitamin D therapy in children with epilepsy have shown little evidence of effect and have been similarly limited by lack of stratification with regard to confounding factors. There is a need for larger studies, using clinically significant outcomes such as fractures, including at risk populations such as symptomatic generalised epilepsy, impaired mobility, and polytherapy. At the present time in the absence of good evidence to the contrary, there remains concern that children with epilepsy are at risk of poor bone health and that vitamin D therapy may be beneficial. As low-dose vitamin D supplementation (400 IU per day) is now recommended for healthy children and it is biologically feasible that children with epilepsy may be at higher risk of clinically significant deficiency, it is important that neurologists ensure that low-dose vitamin D supplementation should be prescribed and compliance followed up in children with epilepsy.

Effects of long-term combination treatment with valproate and atypical antipsychotics on bone mineral density and bone metabolism in premenopausal patients with bipolar disorder: a preliminary study

OBJECTIVE

We investigated bone mineral density (BMD) and bone metabolism in female bipolar patients who were undergoing long-term treatment with valproate combined with a low-dose atypical antipsychotic.

METHODS

Nineteen premenopausal women with bipolar disorder who were treated with valproate combined with atypical antipsycho-tics for at least 2 years were evaluated. The BMD was measured at lumbar spine and femur sites using dual-energy X-ray absorptiometry (DE-XA). The biochemical markers of bone turnover and circulating levels of gonadal hormones were assessed. Subjects with abnormal DEXA scans were compared to those with normal scans.

RESULTS

Nine (47%) of nineteen subjects showed osteopenia or osteoporosis. The T-score for subjects with abnormal DEXA scans was -1.988. Decreased BMD was more prominent in the proximal femur than in the lumbar spine. Subjects with abnormal DEXA scans had high phosphorus and low testosterone levels relative to subjects with normal scans (p=0.008 and p=0.028, respectively). There was a significant negative correlation between phosphorus, osteocalcin, and femur neck BMD (p<0.05). However, multivariate analysis did not show a significant association between femur and lumbar BMD and biochemical markers of bone turnover.

CONCLUSION

Long-term treatment with valproate combined with low-dose atypical antipsychotics may adversely affect BMD in premenopausal women with bipolar disorder. A prospective, controlled-study with a larger population is warranted, and assessment of BMD and bone metabolism should be taken into consideration in long-term therapy with valproate and atypical antipsychotics.

Suberoylanilide hydroxamic acid (SAHA; vorinostat) causes bone loss by inhibiting immature osteoblasts

Histone deacetylase (Hdac) inhibitors are used clinically to treat cancer and epilepsy. Although Hdac inhibition accelerates osteoblast maturation and suppresses osteoclast maturation in vitro, the effects of Hdac inhibitors on the skeleton are not understood. The purpose of this study was to determine how the pan-Hdac inhibitor, suberoylanilide hydroxamic acid (SAHA; a.k.a. vorinostat or Zolinza(TM)) affects bone mass and remodeling in vivo. Male C57BL/6J mice received daily SAHA (100mg/kg) or vehicle injections for 3 to 4weeks. SAHA decreased trabecular bone volume fraction and trabecular number in the distal femur. Cortical bone at the femoral midshaft was not affected. SAHA reduced serum levels of P1NP, a bone formation marker, and also suppressed tibial mRNA levels of type I collagen, osteocalcin and osteopontin, but did not alter Runx2 or osterix transcripts. SAHA decreased histological measures of osteoblast number but interestingly increased indices of osteoblast activity including mineral apposition rate and bone formation rate. Neither serum (TRAcP 5b) nor histological markers of bone resorption were affected by SAHA. P1NP levels returned to baseline in animals which were allowed to recover for 4weeks after 4weeks of daily SAHA injections, but bone density remained low. In vitro, SAHA suppressed osteogenic colony formation, decreased osteoblastic gene expression, induced cell cycle arrest, and caused DNA damage in bone marrow-derived adherent cells. Collectively, these data demonstrate that bone loss following treatment with SAHA is primarily due to a reduction in osteoblast number. Moreover, these decreases in osteoblast number can be attributed to the deleterious effects of SAHA on immature osteoblasts, even while mature osteoblasts are resistant to the harmful effects and demonstrate increased activity in vivo, indicating that the response of osteoblasts to SAHA is dependent upon their differentiation state. These studies suggest that clinical use of SAHA and other Hdac inhibitors to treat cancer, epilepsy or other conditions may potentially compromise skeletal structure and function.

Histone deacetylases in skeletal development and bone mass maintenance

The skeleton is a multifunctional and regenerative organ. Dynamic activities within the bone microenvironment necessitate and instigate rapid and temporal changes in gene expression within the cells (osteoclasts, osteoblasts, and osteocytes) responsible for skeletal maintenance. Regulation of gene expression is controlled, in part, by histone deacetylases (Hdacs), which are intracellular enzymes that directly affect chromatin structure and transcription factor activity. Key roles for several Hdacs in bone development and biology have been elucidated though in vitro and in vivo models. Recent findings suggest that clinical usage of small molecule Hdac inhibitors for conditions like epilepsy, bipolar disorder, cancer, and a multitude of other ailments may have unintended effects on bone cell populations. Here we review the progress that has been made in the last decade in understanding how Hdacs contribute to bone development and maintenance.

Hdac-mediated control of endochondral and intramembranous ossification

Histone deacetylases (Hdacs) remove acetyl groups (CH3CO-) from ε-amino groups in lysine residues within histones and other proteins. This posttranslational (de) modification alters protein stability, protein-protein interactions, and chromatin structure. Hdac activity plays important roles in the development of all organs and tissues, including the mineralized skeleton. Bone is a dynamic tissue that forms and regenerates by two processes: endochondral and intramembranous ossification. Chondrocytes and osteoblasts are responsible for producing the extracellular matrices of skeletal tissues. Several Hdacs contribute to the molecular pathways and chromatin changes that regulate tissue-specific gene expression during chondrocyte and osteoblast specification, maturation, and terminal differentiation. In this review, we summarize the roles of class I and class II Hdacs in chondrocytes and osteoblasts. The effects of small molecule Hdac inhibitors on the skeleton are also discussed.

Adverse effects of valproate on bone: defining a model to investigate the pathophysiology

PURPOSE

Bone disease and fractures are common with chronic antiepileptic drug (AED) therapy, but the underlying mechanisms are poorly understood. This study aimed to characterize adverse bone effects of valproate and to identify mouse strains either resistant or sensitive to these effects.

METHODS

Seven mouse strains (n = 40/strain; 10/diet) were screened for the effect of chronic (8 weeks) valproate treatment (0, 2, 4, and 6 g/kg food) on total bone mineral content (BMC, by dual energy x-ray absorptiometry). In a confirmatory study the effect of valproate (0 or 4 g/kg food) over 16 weeks was assessed in five of the mouse strains (n = 60/strain; 30/diet) identified in the screening phase as either sensitive or resistant. Ex vivo volumetric bone measures and structural changes were assessed using peripheral quantitative computed tomography (pQCT) and histomorphometry.

RESULTS

Chronic valproate treatment reproducibly affected bone in C3H/HeJ mice, with a 9.1% (p < 0.01) reduction in total BMC and a 10.7% (p < 0.01) reduction in trabecular volumetric density, indicating a sensitive strain to AED-induced bone loss. Histomorphometry was consistent, revealing reductions in trabecular volume (19.6%, p < 0.05) and number (14.3%, p < 0.04), and a 19.9% (p < 0.05) increase in trabecular separation. In contrast the A/J mice were reproducibly resistant to the bone effects.

CONCLUSION

Mouse strains sensitive and resistant to the adverse bone effects of chronic valproate treatment were identified. The strain-specific effects suggest a role of genetic factors in the pathogenesis of AED-induced bone disease. This novel model provides a new, powerful tool to investigate the pathophysiology and therapy of AED-associated bone disease.

Effects of antiepileptic drug therapy on vitamin D status and biochemical markers of bone turnover in children with epilepsy

Reports of decreased serum 25-hydroxyvitamin D (25-OHD) and altered bone metabolism associated with antiepileptic drug (AED) treatment are inconsistent and predominantly restricted to adults. In this cross-sectional observational study, the aim was to evaluate the influence of AED treatment on vitamin D status and markers of bone turnover in children with epilepsy. In 38 children taking AEDs and 44 healthy control subjects, blood samples were collected to determine the levels of serum 25-OHD, intact parathyroid hormone (iPTH), calcium (Ca), phosphate (P), bone alkaline phosphatase (BAP), osteocalcin (OC) and C terminal telopeptide of type I collagen (ICTP). More than 75% of the patients were vitamin D deficient (serum 25-OHD<20 ng/mL) and 21% of the patients had an insufficient vitamin D status (serum 25-OHD=20-30 ng/mL). In the patients, the serum levels of OC (p = 0.002) and BAP (p < 0.001) were significantly increased, but ICTP (p = 0.002) concentrations were significantly decreased compared with the control group. When patients where divided into two groups according to their medication (mono- or polytherapy), significantly lower 25-OHD (p = 0.038) and ICTP (p = 0.005) levels and elevated BAP (p = 0.023) concentrations were found in patients under polytherapy. An association between 25-OHD and the measured bone markers could not be determined. Our results indicate that the prevalence of vitamin D deficiency in epilepsy patients under AED treatment is high, especially under polytherapy, and alteration markers of bone formation and resorption suggests an accelerated skeletal turnover. The routine monitoring of serum 25-OHD and vitamin D supplementation on an individual basis should be considered.

Evaluation of bone turnover in epileptic children using oxcarbazepine

This study evaluated the effects of oxcarbazepine monotherapy on bone turnover in prepubertal and pubertal children. Thirty-four newly diagnosed pediatric patients with normal bone mineral density, serum biochemical markers of bone formation, and hormonal markers participated. Levels of 25-hydroxyvitamin D were significantly decreased after therapy compared with baseline values. Levels of gamma-glutamyl transferase, phosphorus, alkaline phosphatase, osteocalcin, parathyroid hormone, and calcitonin had increased. However, only changes in osteocalcin and gamma-glutamyl transferase levels were statistically significant compared with baseline values. Drug-induced osteopenia was evident in 3 patients with z scores of bone-mineral density less than -2.0, whereas these patients had z scores of less than -1.5 before treatment. Although 18 months of oxcarbazepine treatment exerted slightly adverse effects on bone metabolism, the effect seems insignificant in children with normal bone-mineral density. Although alterations in bone metabolism do not always suffice to explain the decrease in bone-mineral metabolism, we think that patients with osteopenia before the initiation of oxcarbazepine therapy should be followed carefully, especially in long-term treatment.