The risk of asymptomatic hyperammonemia in children with idiopathic epilepsy treated with valproate: Relationship to blood carnitine status

Ketogenic therapy in childhood and adolescence: recommendations of the Brazilian experts group

Ketogenic dietary therapies (KDTs) are a safe and effective treatment for pharmacoresistant epilepsy in children. There are four principal types of KDTs: the classic KD, the modified Atkins diet (MAD), the medium-chain triglyceride (MCT) diet, and the low glycemic index diet (LGID). The International Ketogenic Diet Study Group recommends managing KDTs in children with epilepsy. However, there are no guidelines that address the specific needs of the Brazilian population. Thus, the Brazilian Child Neurology Association elaborated on these recommendations with the goal of stimulating and expanding the use of the KD in Brazil.

Valproic Acid-Associated Hyperammonemia: A Systematic Review

BACKGROUND

Hyperammonemia is an adverse effect that poses clinical uncertainty around valproic acid (VPA) use. The prevalence of symptomatic and asymptomatic hyperammonemia and its relationship to VPA concentration is not well established. There is also no clear guidance regarding its management. This results in variability in the monitoring and treatment of VPA-induced hyperammonemia. To inform clinical practice, this systematic review aims to summarize evidence available around VPA-associated hyperammonemia and its prevalence, clinical outcomes, and management.

METHODS

An electronic search was performed through Ovid MEDLINE, Ovid Embase, Web of Science, and PsycINFO using search terms that identified hyperammonemia in patients receiving VPA. Two reviewers independently performed primary title and abstract screening with a third reviewer resolving conflicting screening results. This process was repeated during the full-text review process.

RESULTS

A total of 240 articles were included. Prevalence of asymptomatic hyperammonemia (5%-73%) was higher than symptomatic hyperammonemia (0.7%-22.2%) and occurred within the therapeutic range of VPA serum concentration. Various risk factors were identified, including concomitant medications, liver injury, and defects in carnitine metabolism. With VPA discontinued, most symptomatic patients returned to baseline mental status with normalized ammonia level. There was insufficient data to support routine monitoring of ammonia level for VPA-associated hyperammonemia.

CONCLUSIONS

Valproic acid-associated hyperammonemia is a common adverse effect that may occur within therapeutic range of VPA. Further studies are required to determine the benefit of routine ammonia level monitoring and to guide the management of VPA-associated hyperammonemia.

Sex differences in side effects of antiseizure medications in pediatric patients with epilepsy: A systematic review

PURPOSE

To perform a systematic review searching for differences in the side effects of antiseizure medications (ASMs) with respect to sex in pediatric patients with epilepsy.

METHODS

We carried out a comprehensive literature search of the PubMed database and all results up to April 2020 were included. Titles, abstracts, and full texts of the articles were screened by two independent reviewers. We included all studies evaluating the side effects of ASMs in patients with epilepsy younger than 18 years, with reference to the two sexes. Studies on ASMs used for indications other than epilepsy were excluded.

RESULTS

A total of 5164 studies were identified. Sixty-seven studies were finally included, 5 of them also including adult patients in the sample. Sixteen studies revealed sex-related differences in side effects of ASMs, disclosing a higher frequency of general side effects in girls: a higher risk of overweight, hyperammonaemia, high leptin levels, and carnitine deficiency in girls on valproic acid; a lower height increase, an increased risk of weight loss, the anecdotical occurrence of acute psychosis in girls on topiramate; a higher risk of retinal toxicity in boys on vigabatrin.

CONCLUSION

The effect of sex on susceptibility to side effects of ASMs is poorly investigated with sparse results, and it could be underestimated. The findings of our study point to the presence of sex differences which should be thoroughly investigated to be confirmed, highlighting the need for a systematic evaluation of sex as a determinant variable influencing the response to medications in clinical research.

Blood Levels of Ammonia and Carnitine in Patients Treated with Valproic Acid: A Meta-analysis

Objective

Long-term valproic acid (VPA) administration is associated with adverse metabolic effects, including hyperammonemia and hypocarnitinemia. However, the pathogeneses of these adverse events remain unclear, and not enough reviews have been performed. The aim of this study was to conduct a meta-analysis of studies examining blood levels of ammonia and carnitine in patients treated with VPA.

Methods

We conducted database searches (PubMed, Web of Science) to identify studies examining blood levels of ammonia and carnitine in patients treated with VPA. A meta-analysis was performed to conduct pre- and post-VPA treatment comparisons, cross-sectional comparisons between groups with and without VPA use, and estimations of the standardized correlations between blood levels of ammonia, carnitine, and VPA.

Results

According to the cross-sectional comparisons, the blood ammonia level in the VPA group was significantly higher than that in the non-VPA group. Compared to that in the non-VPA group, the blood carnitine level in the VPA group was significantly lower. In the meta-analysis of correlation coefficients, the blood VPA level was moderately correlated with blood ammonia and blood free carnitine levels in the random effects model. Furthermore, the blood ammonia level was moderately correlated with the blood free carnitine level.

Conclusion

Although the correlation between ammonia and free carnitine levels in blood was significant, the moderate strength of the correlation does not allow clinicians to infer free carnitine levels from the results of ammonia levels. Clinicians should measure both blood ammonia and free carnitine levels, especially in patients receiving high dosages of VPA.

Effects of l-carnitine supplementation in patients with childhood-onset epilepsy prescribed valproate

BACKGROUND

The benefits of carnitine supplementation in patients treated with valproate (VPA) are not clear. Therefore, we retrospectively explored the benefits of carnitine supplementation by analyzing laboratory data.

METHODS

We measured the serum-free carnitine (FC), VPA, aspartate aminotransferase, alanine aminotransferase, amylase, and ammonia levels, and the platelet count, in 69 patients with childhood-onset epilepsy treated with VPA. Eight patients had received carnitine supplementation. The serum FC and acylcarnitine levels were measured using an enzyme cycling method. We compared laboratory values between patients with and without carnitine supplementation and analyzed the correlations between serum FC levels and laboratory values.

RESULTS

The serum FC levels were normal (median, 48.8 μmol/L; range: 41.9-68.3 μmol/L) in all eight patients with carnitine supplementation, but below normal in 32 of 61 patients without supplementation. The median serum amylase levels were lower in the patients with carnitine supplementation (median, 48 U/L; range: 27-149 U/L) than in those without (median, 7 U/L; range: 14-234 U/L). The platelet count and serum ammonia levels did not differ significantly between patients with and without supplementation. There was no significant correlation between the serum FC level and the platelet count, serum amylase level, or ammonia level.

CONCLUSIONS

Carnitine supplementation helps maintain serum FC levels in patients treated with VPA. The lower serum amylase levels in patients with carnitine supplementation may reflect protective effects of carnitine against latent pancreatic injury.

Carnitine supplementation prevents carnitine deficiency caused by pivalate-conjugated antibiotics in patients with epilepsy prescribed valproate

We measured carnitine levels before and after pivalate-conjugated antibiotic (PCA) use in six patients with epilepsy who were prescribed valproate (VPA). Three of the patients were on carnitine supplementation when PCA use started. Serum FC levels were within the normal range (37.2-49.0 μmol/L) in all six patients before PCA use. After PCA use, the serum free carnitine (FC) levels remained within the normal range (48.0-68.2 μmol/L) in all three patients on carnitine supplementation, but were below the normal range (18.7-30.8 μmol/L) in the three patients not on carnitine supplementation. No remarkable changes in serum VPA levels, platelet count, amylase or ammonia level was evident in any patients in relation to PCA use. Carnitine deficiency due to PCA use was prevented by carnitine supplementation in patients with epilepsy who were taking VPA. Carnitine supplementation can support patients at risk of carnitine deficiency.

Use of dietary and herbal supplements in adult patients with epilepsy

PURPOSE

To study the extent and characteristics of dietary and herbal supplements use in a large cohort of adult patients with epilepsy.

METHODS

This prospective study included 490 patients receiving care at a university epilepsy clinic. A number of variables, including demographics, characteristics of epilepsy and its treatment, comedication as well as data related to supplements intake were collected from medical records and a dedicated questionnaire.

RESULTS

Overall 247 patients (50.4%) took at least one dietary supplement; nearly half (111, 44.9%) of this group took >1 products. Multivitamins and magnesium were the most prevalent supplements. Most of the patients used supplements for general health rather than their epilepsy condition. The average number of supplements and prescription medications used per person was 5.4. Ten percent (25 of 247) of subjects used dietary supplements which could have proconvulsive effect or potential for interaction with prescription medications. Multivariate analysis revealed two independent variables associated with supplements intake, younger age and female sex.

CONCLUSION

Dietary and herbal supplements use is common in patients with epilepsy, adding to the burden of overmedication. Concurrent use of supplements may potentially lead to interactions with prescription medications or loss of seizure control. Health care providers should routinely check for dietary supplements use to limit potential harm related to their intake.

Serum carnitine levels of children with epilepsy: Related factors including valproate

OBJECTIVE

This study measured the serum carnitine levels in patients with epilepsy and determined the factors contributing to low carnitine levels.

METHODS

We measured the serum carnitine levels in 94 consecutive patients with epilepsy, including the free carnitine (FC) and acylcarnitine fractions, using an enzyme cycling method. We defined a low FC as a serum FC level < 36 μmol/L. Age, body mass index (BMI), standard deviation score of BMI (BMI-SDS), use of valproate, cognitive disorder, and feeding problems differed between patients with low and normal FC. In patients taking valproate, the associations of the serum FC level with the platelet count and serum ammonia and amylase levels were analyzed.

RESULTS

Univariate analysis showed that a low BMI and BMI-SDS, the use of valproate, and cognitive disorder were more frequent in patients with a low FC. Logistic regression analysis revealed that a low BMI-SDS and cognitive disorders were independently associated with a low FC. Among the patients taking valproate, a low BMI-SDS and age were associated with a low FC. The serum FC and ammonia levels were inversely correlated, whereas no correlation was observed between the serum FC level and platelet count or serum amylase level.

CONCLUSION

A low BMI and cognitive disorders were related to a low FC in patients with epilepsy and the serum carnitine levels should be monitored in these patients.

The effect of antiepileptic drugs on the kidney function and structure

INTRODUCTION

Long-term use of antiepileptic drugs (AEDs) is associated with number of somatic conditions. Data from experimental, cross-sectional and prospective studies have evidence for the deleterious effect of some AEDs on the kidney. Areas covered: This review summarized the current knowledge of the effect of AEDs on the kidney including evidence and mechanisms. Fanconi syndrome was reported with valproate (VPA) therapy in severely disabled children with epilepsy. Renal tubular acidosis and urolithiasis were reported with acetazolamide, topirmate and zonisamide, drugs with carbonic anhydrase inhibition properties. Increased levels of urinary N-acetyl-beta-D-glucosaminidase (NAG) to urinary creatinine (U-NAG/UCr), urinary excretion of α1-micrglobulin, β-galactosidase activity; and urinary malondialdehyde to creatinine (MDA/Cr), markers of renal glomerular and tubular injury, were reported with chronic use of some AEDs (VPA, carbamazepine and phenytoin). The mechanism(s) of kidney dysfunction/injury induced by AEDs is unknown. Experimental and clinical studies have shown that VPA induces oxidative stress, mitochondrial deficits, carnitine deficiency and inflammation and fibrosis in renal tissue in mice and in vitro studies. Expert commentary: It seems reasonable to monitor kidney function during treating patients with epilepsy at high risk of kidney injury (e.g. on combined therapy with more than one AED, severely disabled children, etc).

Association between the blood concentrations of ammonia and carnitine/amino acid of schizophrenic patients treated with valproic acid

Background

Administration of valproic acid (VPA) is complicated with approximately 0.9% of patients developing hyperammonemia, but the pathogenesis of this adverse effect remains to be clarified. The aim of the present study was to search for mechanisms associated with VPA-induced hyperammonemia in the light of changes in serum amino acids concentrations associated with the urea cycle of schizophrenic patients.

Method

Blood samples (10 mL) were obtained from 37 schizophrenic patients receiving VPA for the prevention of violent behaviors in the morning after overnight fast. Blood concentrations of ammonia, VPA, free carnitine, acyl-carnitine, and 40 amino acids including glutamate and citrulline were measured for each patient. Univariate and multivariate regression analyses were performed to identify amino acids or concomitantly administered drugs that were associated with variability in the blood concentrations of ammonia.

Result

The blood ammonia level was positively correlated with the serum glutamate concentration (r = 0.44, p < 0.01) but negatively correlated with glutamine (r = −0.41, p = 0.01), citrulline (r = −0.42, p = 0.01), and glycine concentrations (r = −0.54, p < 0.01). It was also revealed that the concomitant administration of the mood stabilizers (p = 0.04) risperidone (p = 0.03) and blonanserin (p < 0.01) was positively associated with the elevation of the blood ammonia level.

Conclusion

We hypothisized that VPA would elevate the blood ammonia level of schizophrenic patients. The observed changes in serum amino acids are compatible with urea cycle dysfunction, possibly due to reduced carbamoyl-phosphate synthase 1 (CPS1) activity. We conclude that VPA should be prudently prescribed to schizophrenic patients, particularly those receiving mood stabilizers or certain antipsychotics.

Hyperammonemia induced by prophylactic administration of antiepileptic drugs during the perioperative period of craniotomy

BACKGROUND

Antiepileptic drugs (AEDs) are increasingly used prophylactically during the perioperative period to prevent epilepsy in patients undergoing craniotomy. Evidence concerning the use of AEDs and the incidence, extent and risk factors of hyperammonemia induced by different types of AEDs is lacking.

METHODS

Patients were divided into groups with 3 different AED regimens, levetiracetam, valproate and carbamazepine regimens, and the blood ammonia concentration and liver and coagulation functions were assessed during the perioperative period.

RESULTS

Sixty-five patients were enrolled consecutively and the postoperative hyperammonemia was found in 46 patients (70.77%), and 45 (97.83%) were asymptomatic. A total of 80.95% of the patients using valproate developed hyperammonemia, and the postoperative blood ammonia concentration continued to rise in 61.90% of these patients. Additionally, valproate had the least impact on liver enzymes. The synthetic function of the liver in patients with higher concentrations of preoperative blood ammonia was more seriously damaged than that in patients with normal postoperative ammonia concentrations.

CONCLUSIONS

Selection of AED for patients undergoing craniotomy should be based on the individual medical situation. Carbamazepine may be a proper choice for the majority of these patients, while valproate is likely to be more appropriate for patients with abnormal liver aminotransferases.

Levocarnitine induced seizures in patients on valproic acid: A negative systematic review

OBJECTIVE

Warnings of L-carnitine induced seizures are recorded on product monographs and pharmacy databases, without any referenced literature. This medication can potentially improve the hospital course in those patients with valproic acid (VPA) induced hyperammonemic encephalopathy, but may be withheld because of this warning. The goal was to perform an extensive systematic review of the literature to document the incidence of levocarnitine (L-carnitine) induced seizures in those patients on VPA therapy.

METHODS

Articles from MEDLINE, BIOSIS, EMBASE, Global Health, Scopus, Cochrane Library, the International Clinical Trials Registry Platform, clinicaltrials.gov (inception to June 2015), and reference lists of relevant articles were searched. The strength of evidence was to be adjudicated using both the Oxford and GRADE methodology by two independent reviewers.

RESULTS

We failed to identify a single study implicating L-carnitine supplementation leading to seizures in any patient on VPA therapy. This contradicts all quoted, but unsubstantiated, concerns on product monographs and pharmacy databases related to seizure induction/propagation with L-carnitine supplementation.

CONCLUSION

There is no literature available to support claims of L-carnitine induced seizures during supplementation in patients on VPA therapy for seizures. This contradicts quoted, but not referenced, concerns on the product monograph. In patients suffering from hypocarnitinemia or hyperammonemic encephalopathy while on VPA, L-carnitine supplementation can be considered knowing there is no data to support seizure propagation or induction with administration of this supplement.

Markers of bone turnover in patients with epilepsy and their relationship to management of bone diseases induced by antiepileptic drugs

Data from cross-sectional and prospective studies revealed that patients with epilepsy and on long-term treatment with antiepileptic drugs (AEDs) are at increased risk for metabolic bone diseases. Bone diseases were reported in about 50% of patients on AEDs. Low bone mineral density, osteopenia/osteoporosis, osteomalacia, rickets, altered concentration of bone turnover markers and fractures were reported with phenobarbital, phenytoin, carbamazepine, valproate, oxcarbazepine and lamotrigine. The mechanisms for AEDs-induced bone diseases are heterogeneous and include hypovitaminosis D, hypocalcemia and direct acceleration of bone loss and/or reduction of bone formation. This article reviews the evidence, predictors and mechanisms of AEDs-induced bone abnormalities and its clinical implications. For patients on AEDs, regular monitoring of bone health is recommended. Prophylactic administration of calcium and vitamin D is recommended for all patients. Treatment doses of calcium and vitamin D and even anti-resorptive drug therapy are reserved for patients at high risk of pathological fracture.

Carnitine deficiency: Risk factors and incidence in children with epilepsy

BACKGROUND

Carnitine deficiency is relatively common in epilepsy; risk factors reportedly include combination antiepileptic drug (AED) therapy with valproic acid (VPA), young age, intellectual disability, diet and enteral or parenteral feeding. Few studies have examined the correlation between each risk factor and carnitine deficiency in children with epilepsy. We examined the influence of these risk factors on carnitine deficiency, and identified a formula to estimate plasma free carnitine concentration in children with epilepsy.

METHODS

Sixty-five children with epilepsy and 26 age-matched controls were enrolled. Plasma carnitine concentrations were measured using an enzyme cycling assay, and correlations were sought with patients' other clinical characteristics.

RESULTS

Carnitine deficiency was found in approximately 17% of patients with epilepsy and was significantly associated with carnitine-free enteral formula only by tube feeding, number of AEDs taken (independent of VPA use), body weight (BW), body height and Gross Motor Function Classification System (GMFCS) score. Stepwise multiple linear regression analysis indicated that carnitine concentration (in μmol/L) could be accurately estimated from a formula that does not require blood testing: 42.44+0.14×(BW in kg)-18.16×(feeding)-3.19×(number of AEDs), where feeding was allocated a score of 1 for carnitine-free enteral formula only by tube feeding and 0 for taking food orally (R(2)=0.504, P<0.001).

CONCLUSIONS

Carnitine-free enteral formula only by tube feeding, multiple AED treatment and low BW are risk factors for carnitine deficiency in children with epilepsy. l-carnitine should be administered to children at risk of deficiency to avoid complications. Treatment decisions can be informed using an estimation formula that does not require blood tests.

Seminal fluid analysis and testicular volume in adults with epilepsy receiving valproate

Epilepsy and its medications adversely affect reproductive and sexual functions and fertility. This study aimed to assess sperm parameters and testicular volume in men with epilepsy on valproate (VPA). Included were 55 patients with idiopathic epilepsy with a mean age of 31.86 ± standard deviation (SD) 6.55 years, mean illness duration of 12.50 ± SD 5.10 years, and a mean treatment time of 9.55 ± SD 0.85 years. Sex hormone profile, semen analysis, testicular volume and total seminal plasma carnitine were determined. Compared to controls, patients had lower levels of free testosterone (p<0.01), sperm concentration (p<0.0001) and count (p<0.0001), carnitine (p<0.01), and testicular volume (p<0.01), and higher rates of immotile sperm (p<0.001) and abnormal forms (p<0.0001). Significant correlations were identified between sperm count, motility, immotile sperm, abnormal forms, testicular volume, carnitine levels and duration of illness, duration of treatment with VPA and VPA dose. Multivariable analysis demonstrated that duration of treatment with VPA, sperm count, motility and abnormal forms were significantly associated with seminal plasma carnitine. Long-term VPA treatment is adversely associated with reduced sperm count and motility, increased abnormal sperm count and reduced testicular volume. This may contribute to reduced fertility.

Seminal fluid analysis and testicular volume in adults with epilepsy receiving valproate

Epilepsy and its medications adversely affect reproductive and sexual functions and fertility. This study aimed to assess sperm parameters and testicular volume in men with epilepsy on valproate (VPA). Included were 55 patients with idiopathic epilepsy with a mean age of 31.86 ± standard deviation (SD) 6.55 years, mean illness duration of 12.50 ± SD 5.10 years, and a mean treatment time of 9.55 ± SD 0.85 years. Sex hormone profile, semen analysis, testicular volume and total seminal plasma carnitine were determined. Compared to controls, patients had lower levels of free testosterone (p<0.01), sperm concentration (p<0.0001) and count (p<0.0001), carnitine (p<0.01), and testicular volume (p<0.01), and higher rates of immotile sperm (p<0.001) and abnormal forms (p<0.0001). Significant correlations were identified between sperm count, motility, immotile sperm, abnormal forms, testicular volume, carnitine levels and duration of illness, duration of treatment with VPA and VPA dose. Multivariable analysis demonstrated that duration of treatment with VPA, sperm count, motility and abnormal forms were significantly associated with seminal plasma carnitine. Long-term VPA treatment is adversely associated with reduced sperm count and motility, increased abnormal sperm count and reduced testicular volume. This may contribute to reduced fertility.

Risk factors of hyperammonemia in patients with epilepsy under valproic acid therapy

Hyperammonemia has been reported to be associated with patients who receive valproic acid (VPA) therapy. This study aimed to determine the risk factors for hyperammonemia in patients with epilepsy treated with VPA. One hundred and fifty-eight adult patients with epilepsy aged older than 17 years who received VPA therapy were enrolled into this study. Blood samples were taken during the interictal state and analyzed for the blood level of ammonia. Statistical analysis was conducted between different groups of patients. The results showed that the frequency of hyperammonemia associated with VPA therapy was 27.8% (ammonia level >93 µg/dL), and 5.1% of the patients had severe hyperammonemia (ammonia level >150 µg/dL). The blood ammonia level was significantly correlated with the dosage of VPA and the plasma concentration of VPA. An increase of 1 mg in the dosage of VPA increased the risk of hyperammonemia by 0.1%. In addition, combination treatment with liver enzyme inducing antiepileptic drugs (AEDs) and antipsychotic drugs increased the risk of hyperammonemia. In conclusion, the use of VPA in adult patients with epilepsy was associated with a dose-dependent increase in blood concentrations of ammonia. Combination treatment with liver enzyme-inducing AEDs and antipsychotic drugs increased the risk of VPA-induced hyperammonemia. Most of the patients with VPA-induced hyperammonemia were asymptomatic; however, if patients taking VPA present with symptoms such as nausea, fatigue, somnolence, ataxia, and consciousness disturbance, the blood ammonia level should be measured.

Serum carnitine level and its associated factors in patients with chronic viral hepatitis

ABSTRACT: 

Aim: Serum carnitine level and its associated factors have been evaluated in patients with chronic viral hepatitis. Methods: Patients with confirmed chronic viral hepatitis based on the serological markers and liver biopsy were included. In total, 86 volunteers and 86 patients with chronic viral hepatitis completed the study. Demographic data, type of treatment regimen and nutritional status of the patients were recorded and one blood sample was collected from each patient after an overnight fasting. A double antibody sandwich ELISA kit was used to measure carnitine serum level. Results: Mean ± standard deviation of serum carnitine level in the case and control groups were 34.3 ± 15.3 and 55.7 ± 28.4 μmol/l, respectively (p = 0.001). Regarding carnitine deficiency definition, 64 out of 86 patients (74.4%) and 21 out of 86 (24.5%) healthy individuals suffered from carnitine deficiency (p < 0.001). Carnitine dietary intake was significantly lower (p < 0.001). Compared with patients with chronic hepatitis C infection, a more severe form of carnitine deficiency was detected in patients with chronic hepatitis B infection (18.39 ± 15.68 μmol/l vs 42.30 ± 32.92 μmol/l; p = 0.03). In addition, serum carnitine level (41.1 ± 14.8 μmol/l) was significantly higher in the cirrhotic than noncirrhotic patients (31.60 ± 13.2 μmol/l; p = 0.04). Conclusion: Although the cirrhotic patients had higher serum carnitine level compared with noncirrhotic patients, serum carnitine level in the patients with chronic hepatitis was significantly lower than the healthy individuals. Also compared with the defined cut-off point for normal carnitine serum level, carnitine deficiency was common in Iranian patients with chronic hepatitis.

Valproate-induced hyperammonemia in juvenile ceroid lipofuscinosis (Batten disease)

PURPOSE

Valproate-induced hyperammonemia (VHA) and hyperammonemic encephalopathy (VHE) are well-known complications of valproate (VPA) treatment. Currently recognised risk factors for VHE include a high VPA dosage, the need for polytherapy and long duration of treatment. Despite the severe nature of the epilepsy, presence of concomitant psychiatric manifestations, and frequent need for poly-pharmacy associated with juvenile ceroid lipofuscinosis (JNCL, Batten disease) neither this disorder nor other subtypes of neuronal ceroid lipofuscinosis have previously been identified as risk factors for VHA/VHE. The aim of the present publication is to describe four cases with VHE in a well-defined Danish population of JNCL.

METHOD

An examination of medical records of all 35 patients with JNCL in Denmark was conducted and revealed fourteen patients treated with VPA.

RESULTS

Four patients treated with VPA developed VHE. All patients were prescribed VPA in standard dosages, had normal plasma concentrations of VPA and received antiepileptic drug (AED) polytherapy. Symptoms occurred shortly after commencement or increase in dose of VPA, and were quickly reversible upon discontinuation of VPA. Carnitine supplement was administrated in two patients, which resulted in resolution of symptoms and normalized ammonium levels.

CONCLUSION

Patients with JNCL are in great risk of developing VHA and VHE due to a high rate of polytherapy. Furthermore, studies have shown that carnitine level can be depressed in JNCL, which may increase the risk of VHA and VHE. We recommend that increased attention should be given to these patients.

Adverse drug reactions induced by valproic acid

Valproic acid is a widely-used first-generation antiepileptic drug, prescribed predominantly in epilepsy and psychiatric disorders. VPA has good efficacy and pharmacoeconomic profiles, as well as a relatively favorable safety profile. However, adverse drug reactions have been reported in relation with valproic acid use, either as monotherapy or polytherapy with other antiepileptic drugs or antipsychotic drugs. This systematic review discusses valproic acid adverse drug reactions, in terms of hepatotoxicity, mitochondrial toxicity, hyperammonemic encephalopathy, hypersensitivity syndrome reactions, neurological toxicity, metabolic and endocrine adverse events, and teratogenicity.

Risk factors for hyperammonemia in pediatric patients with epilepsy

PURPOSE

To identify risk factors for hyperammonemia in pediatric patients with epilepsy.

METHODS

A total of 2,944 pediatric patients (ages 0-15 years) were classified into the following three groups: a group without drug treatment (n = 445, group I), a group receiving antiepileptic drugs other than valproic acid (VPA) (n = 673, group II), and a VPA-treated group (n = 1,826, group III). Hyperammonemia was defined as a plasma ammonia level exceeding 100 μg/dl with reference to the standard range and previous reports.

KEY FINDINGS

The mean ammonia level of groups I, II, and III was 36.0, 56.0, and 86.8 μg/dl, respectively, and the incidence of hyperammonemia was 1.6%, 7.7%, and 31.7%, respectively. In each group, the mean ammonia level of patients aged 3 years or younger was significantly higher than that of patients aged 4-15 years. In group II, concomitant use of topiramate and zonisamide were risk factors for hyperammonemia (adjusted odds ratio [OR] 3.9, 95% confidence interval [CI] 1.7-9.2, and OR 3.5, 95% CI 1.9-6.5, respectively). In group III, the ammonia level increased in a VPA dose-dependent manner. At a VPA dose of 30 mg/kg, there was 4.3-fold increase in the incidence of hyperammonemia. The other significant risk factors identified were female gender (OR 1.3, 95% CI 1.0-1.6), symptomatic generalized epilepsy (OR 1.4, 95% CI 1.1-1.8), and the concomitant use of phenytoin (OR 4.7, 95% CI 3.3-6.9), phenobarbital (OR 2.2. 95% CI 1.6-3.2), acetazolamide (OR 6.6, 95% CI 2.5-17.2), topiramate, or zonisamide.

SIGNIFICANCE

A young age and concomitant use of carbonic anhydrase inhibitors are associated with an increased risk of hyperammonemia regardless of whether the patient is taking VPA. In patients receiving VPA, concomitant use of phenytoin and/or phenobarbital enhances the risk of hyperammonemia. An increase in ammonia can be caused by multiple factors. Our results may help clinicians to avoid problems of hyperammonemia.

Risk factors for hyperammonemia associated with valproic acid therapy in adult epilepsy patients

Hyperammonemia is one of the side effects of treatment with valproic acid (VPA), but the risk factors and mechanisms involved remain obscure. This study analyzed the risk factors for hyperammonemia associated with VPA therapy in adult epilepsy patients. A retrospective analysis of 2724 Japanese patients (1217 males and 1507 females aged from 16 to 76years) treated with VPA between January 2006 and December 2010 were analyzed. The ammonia level increased markedly in a VPA dose-dependent manner, and was significantly elevated in patients who also used hepatic enzyme inducers such as phenytoin (PHT), phenobarbital (PB), carbamazepine (CBZ), and combinations of these drugs. When a blood ammonia level exceeding 200μg/dl was defined as hyperammonemia, the risk factors for hyperammonemia according to multiple regression analysis were a VPA dose >20mg/kg/day (odds ratio (OR): 4.1; 95% confidence interval (CI): 1.6-10.8) and concomitant use of PHT (OR: 11.0; 95% CI: 3.1-38.7), concomitant PB (OR: 4.3; 95% CI: 1.0-17.9), concomitant CBZ (OR: 2.8; 95% CI: 0.6-11.9), and concomitant topiramate (OR: 2.8; 95% CI: 1.2-6.5). Regimens containing multiple inducers were associated with an increased risk of hyperammonemia. Identification of risk factors for hyperammonemia associated with VPA therapy can help to minimize side effects during its clinical use.

Influences of bone and mineral metabolism in epilepsy

INTRODUCTION

Patients with epilepsy are at increased risk for metabolic bone disease, low bone mineral density and fractures.

AREAS COVERED

This article reviews the predictors and mechanisms of bone loss in patients with epilepsy. It provides information regarding the basic bone biology, evidences of osteopathy with epilepsy and the potential mechanisms of its pathogenesis. This review shows that long-term use of antiepileptic drugs (AEDs) is associated with the risk of osteopathy. However, age, gender, low body mass, severity of epilepsy, co-morbid conditions, institutionalization and calcium and vitamin D deficiencies are additional and modified risk factors. AEDs may indirectly accelerate bone loss through hypovitaminosis D, hypocalcemia and hyperparathyroidism or reduce bone accrual through decreasing the levels of calcitonin, growth factors and vitamin K. Also, AEDs may directly accelerate osteoclastic (bone loss) and/or reduce osteoblastic (bone formation) activities, the main cells involved in bone remodeling.

EXPERT OPINION

Understanding the basic bone biology and the pathophysiology of the disturbed bone and mineral metabolism in epilepsy will aid in identification and monitoring of patients at risk and in planning appropriate prophylactic and therapeutic measures.

The real mechanism of VPA-induced hyperammonemia remains unknown

Valproic acid (VPA) is a well-tolerated and effective agent for the treatment of epilepsy, bipolar disorder, and schizoaffective disorder. Several case reports have indicated that VPA may induce serious symptomatic hyperammonemia. Based on analysis of susceptible patients, several possible mechanisms and risk factors have been proposed to identify the patients at risk. Nevertheless, we report the case of a schizoaffective patient who developed severe hyperammonemia occurring after brief exposure to VPA, despite the absence of any known risk factors. Until now, early recognition of the signs and symptoms of hyperammonemia is crucial to managing this unusual adverse reaction.