Non-dose-related side effects of valproate

Non-Dose-Dependent Changes in Liver Enzyme Levels of Children With Epilepsy on Treatment With Sodium Valproate

Background:

Sodium valproate (VPA) is considered as the drug of choice for the treatment of generalized epilepsy in children. Sodium Valproate may be hepatotoxic.

Aim:

To assess the level of derangement of liver enzymes in children with epilepsy on treatment with sodium valproate.

Methods:

A cohort study. One hundred fifty-three children, comprising 51 with epilepsy on treatment with VPA (group I), 51 with epilepsy on treatment with other antiepileptic drugs (AEDs) but not VPA (group II), and 51 with nonconvulsive disorders (group III) had liver function tests performed for them. Data were analyzed by SPSS version 23.0.

Results:

There were 85 males and 68 females, aged 6 months to 14 years (median = 7.0 years). There was no significant difference in the mean plasma levels of alanine transaminase (ALT), alkaline phosphatase, and gamma glutamyl transferase across the three groups of children. The mean aspartate transaminase level was significantly higher in children in group III. There was a statistically significant negative correlation between the duration of AED therapy and the mean serum level of AST (r = −0.266, P = 0.016). The serum ALT level showed a statistically significant positive correlation with the duration of AED therapy (r = 0.268, P = 0.015).

Conclusion:

Sodium valproate monotherapy does not appear to be associated with significant hepatotoxicity in children in our cohort.

Pharmacotherapy for Focal Seizures in Children and Adolescents

Focal-onset seizures are among the most common forms of seizures in children and adolescents and can be caused by a wide diversity of acquired or genetic etiologies. Despite the increasing array of antiseizure drugs available, treatment of focal-onset seizures in this population remains problematic, with as many as one-third of children having seizures refractory to medications. This review discusses contemporary concepts in focal seizure classification and pathophysiology and describes the antiseizure medications most commonly chosen for this age group. As antiseizure drug efficacy is comparable in children and adults, here we focus on pharmacokinetic aspects, drug-drug interactions, and side effect profiles. Finally, we provide some suggestions for choosing the optimal medication for the appropriate patient.

The long-term safety of antiepileptic drugs

Antiepileptic drugs (AEDs) are used by millions of people worldwide for the treatment of epilepsy, as well as in many other neurological and psychiatric conditions. They are frequently associated with adverse effects (AEs), which have an impact on the tolerability and success of treatment. Half the people who develop intolerable AEs discontinue treatment early on after initiation, while the majority of people will continue to be exposed to their effects for long periods of time. The long-term safety of AEDs reflects their potential for chronic, cumulative dose effects; rare, but potentially serious late idiosyncratic effects; late, dose-related effects; and delayed, teratogenic or neurodevelopmental effects. These AEs can affect every body system and are usually insidious. With the exception of delayed effects, most other late or chronic AEs are reversible. To date, there is no clear evidence of a carcinogenic effect of AEDs in humans. While physicians are aware of the long-term AEs of old AEDs (the traditional liver enzyme-inducing AEDs and valproate), information about AEs of new AEDs (such as lamotrigine, levetiracetam, oxcarbazepine, topiramate or zonisamide), particularly of their teratogenic effects, has emerged over the years. Sporadic publications have raised issues about AEs of the newer AEDs eslicarbazepine, retigabine, rufinamide, lacosamide and perampanel but their long-term safety profiles may take years to be fully appreciated. Physicians should not only be aware of the late and chronic AEs of AEDs but should systematically enquire and screen for these according to the individual AED AE profile. Care should be taken for individuals with comorbid conditions that may render them more susceptible to specific AEs. Prevention and appropriate management of long-term AED AEs is expected to improve adherence to treatment, quality of life and control of epilepsy.

Nonalcoholic fatty liver disease in adolescents receiving valproic acid

OBJECTIVE

The aim of this study was to investigate the association between the metabolic derangements induced by valproic acid (VPA) and ultrasound-diagnosed nonalcoholic fatty liver disease (NAFLD) in adolescents.

METHODS

Using a cross-sectional design, we evaluated 86 adolescents with epilepsy who had received VPA monotherapy. Subjects for comparison were 67 normal-weight and 43 weight-matched adolescents. Participants underwent hepatic ultrasound, anthropometric evaluations, and biochemical tests.

RESULTS

Although the occurrence of ultrasound-diagnosed NAFLD was higher in VPA-treated patients than in normal-weight controls (36.0% vs 7.5%, P<0.001), it was similar in VPA-treated patients and weight-matched controls (36.0% vs 34.9%, P>0.05). The identified predictors of NAFLD in VPA-treated patients were abdominal obesity (OR=3.2, 95% CI=2.1-6.8), insulin resistance (OR=2.8, 95% CI=1.7-5.2), metabolic syndrome (OR=2.6, 95% CI=1.4-4.8), and generalized obesity (OR=1.9, 95% CI=1.2-3.7).

CONCLUSION

Valproic acid monotherapy is associated with NAFLD in a high percentage of adolescents with epilepsy who have typical VPA-related metabolic disturbances.

Altering the trajectory of early postnatal cortical development can lead to structural and behavioural features of autism

BACKGROUND

Autism is a behaviourally defined neurodevelopmental disorder with unknown etiology. Recent studies in autistic children consistently point to neuropathological and functional abnormalities in the temporal association cortex (TeA) and its associated structures. It has been proposed that the trajectory of postnatal development in these regions may undergo accelerated maturational alterations that predominantly affect sensory recognition and social interaction. Indeed, the temporal association regions that are important for sensory recognition and social interaction are one of the last regions to mature suggesting a potential vulnerability to early maturation. However, direct evaluation of the emerging hypothesis that an altered time course of early postnatal development can lead to an ASD phenotype remains lacking.

RESULTS

We used electrophysiological, histological, and behavioural techniques to investigate if the known neuronal maturational promoter valproate, similar to that in culture systems, can influence the normal developmental trajectory of TeA in vivo. Brain sections obtained from postnatal rat pups treated with VPA in vivo revealed that almost 40% of cortical cells in TeA prematurely exhibited adult-like intrinsic electrophysiological properties and that this was often associated with gross cortical hypertrophy and a reduced predisposition for social play behaviour.

CONCLUSIONS

The co-manifestation of these functional, structural and behavioural features suggests that alteration of the developmental time course in certain high-order cortical networks may play an important role in the neurophysiological basis of autism.

Oxidative Stress as a Mechanism of Valproic Acid-Associated Hepatotoxicity

Valproic acid (2-n-propylpentanoic acid; VPA) has several therapeutic indications, but it is used primarily as an anticonvulsant. VPA is a relatively safe drug, but its use is associated with idiosyncratic hepatotoxicity, which in some cases may lead to fatality. The underlying mechanism responsible for the hepatotoxicity is still not well understood, but various hypotheses have been proposed, including oxidative stress. This article discusses the experimental evidence on the effect of VPA on the various indices of oxidative stress and on the potential role of oxidative stress in VPA-associated hepatotoxicity.

Modulation of pentylenetetrazole-induced seizures and oxidative stress parameters by sodium valproate in the absence and presence of N-acetylcysteine

In view of a role of oxidative stress in epilepsy and the evidence for the involvement of peroxidative injury in sodium valproate (SVP)-induced adverse effects on liver and kidneys, we investigated whether the combination of SVP with N-acetylcysteine (NAC), an antioxidant, may help us to achieve maximal efficacy in terms of seizure control, with minimal toxicity on liver and kidneys. Pentylenetetrazole (PTZ)-induced seizures were used to evaluate the anticonvulsant effect of drugs. Biochemical estimations included the determination of oxidative stress markers like thiobarbituric acid-reactive substances in brain tissue and glutathione (GSH) levels in liver and kidney tissues. Aspartate aminotransferase and alanine aminotransferase concentrations in the serum were also determined to assess liver function. In our study, NAC exhibited a nondose-dependent anticonvulsant effect. The concurrent administration of NAC with SVP significantly prolonged the latency to jerks, myoclonus and clonic generalized seizures. No significant oxidative stress was evident in brain tissue following PTZ-induced seizures, though an elevation of serum transaminase enzymes was seen. SVP at the dose studied did not produce any significant oxidative stress on the liver and kidneys, while treatment with NAC elevated liver and kidney GSH levels. The concurrent administration of NAC with SVP had beneficial effects on liver and kidney cells.

Safety and Tolerability of the Ketogenic Diet in Pediatric Epilepsy: Effects of Valproate Combination Therapy

PURPOSE

To evaluate safety and tolerability of ketogenic diet (KGD) and valproate (VPA) cotherapy in the treatment of intractable seizures.

METHODS

The patient records of children who underwent KGD initiation at the Massachusetts General Hospital for Children from February 2002 to September 2004 were retrospectively assessed. Efficacy was measured by comparing reported seizure frequency at baseline and at 3-month intervals thereafter. Adverse events and reasons for terminating the diet were tabulated.

RESULTS

Of 71 patients who underwent KGD initiation, 24 were concomitantly using VPA at the time of initiation. The most serious adverse events were two cases of acute pancreatitis (2.8%), both of which occurred in patients not taking VPA. The most common complications in both groups were acidosis (39.4%), nausea and vomiting (23.9%), hypertriglyceridemia (21.1%), lethargy (18.3%), and behavioral changes and irritability (15.5%). No significant difference in adverse-event profiles was found between the VPA group and the non-VPA group. At 1 year, 32 patients remained on the diet, including 11 in the VPA group. Efficacy was nearly identical in these two groups.

CONCLUSIONS

KGD and VPA combination therapy is relatively safe and effective in refractory pediatric epilepsy. Adverse-event profiles of patients on KGD and VPA cotherapy are similar to those of patients on the KGD without VPA. In considering possible treatment options for intractable seizures, cotherapy with these two modalities should not be excluded for safety or tolerability concerns. In some patients, this combination may provide optimal seizure control.

Initiation of treatment and selection of antiepileptic drugs in childhood epilepsy

PURPOSE

A retrospective study was carried out on 53 cases with childhood epilepsy to evaluate the validity of the initial selection of antiepileptic drug (AED).

METHODS

We investigated the AEDs selected at the beginning of the treatment from the medical records of 53 untreated cases. A follow-up study was undertaken to evaluate the effects of the AEDs. In the second study, we investigated the AEDs of 10 cases with atypical benign partial epilepsy (ABPE), to clarify whether the initial AEDs selected for rolandic epilepsy were related to the appearance of ABPE.

RESULTS

The AEDs used at the initial stage consisted of carbamazepine (CBZ), valproic acid (VPA), phenobarbital (PB), and vitamin B6. The main AEDs were CBZ and VPA for localization-related epilepsy, and VPA for generalized epilepsy. The initial selection of AEDs in 41 (85.4%) of 48 cases treated with AEDs were considered to be correct from the results of follow-up. We could not specify any AEDs that related to the appearance of ABPE.

CONCLUSIONS

The selection of AED in this series was considered to be most appropriate. We proposed a criterion to determine whether to begin the AED treatment immediately at the initial seizure.

Sodium valproate induces apoptosis in the rat hepatoma cell line, FaO

Sodium valproate (VPA) is clinically employed as an anti-convulsant and, to a lesser extent, mood stabilizer. While the incidence of toxicity associated with the clinical use of valproate is low, serious hepatotoxicity makes up a significant percentage. Rats treated with high doses of sodium valproate are subject to hepatotoxicity, and the study of the molecular mechanisms underlying this phenomenon may shed further light on the human situation. Exposure to sodium valproate results in the down regulation in rat liver of several transcripts whose products are involved in cellular energy homeostasis, resulting in time-dependent fluctuations in cellular ATP, possibly resulting in cell death. To further examine this, classical markers of apoptosis were examined in the rat hepatoma cell line FaO following sodium valproate exposure. Concentrations greater than 300 microM sodium valproate resulted in a transient wave of apoptosis, as assessed by chromatin condensation and DNA fragmentation assay. Analysis indicated that Fas-ligand and caspase-11 expression were increased at the transcriptome level, while caspase-3 was activated at the proteome level during the exposure period. These data demonstrates that sodium valproate causes cell death through apoptosis in a rat liver cell line, and provides information on the possible molecular mechanisms underlying this phenomenon in vivo.

Fatal sodium valproate-induced hypersensitivity syndrome with lichenoid dermatitis and fulminant hepatitis

Anticonvulsant hypersensitivity syndrome caused by sodium valproate (Depakene) has rarely been reported. Here we describe a patient who presented with nonspecific polymorphous eruptions, fulminant hepatitis, and jaundice. Lichenoid dermatitis was found in the skin biopsy specimen. Toxic hepatitis and microvesicular steatosis were found in the liver biopsy specimen, consistent with valproate hepatotoxicity.

Valproate: past, present, and future

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

Topiramate enhances the risk of valproate-associated side effects in three children

PURPOSE

We present three children with severe therapy-refractory epilepsy who tolerated valproate (VPA) well in various combinations with other antiepileptic drugs (AEDs) but developed typical VPA side effects in combination with topiramate (TPM).

METHODS

The clinical symptoms began with apathy in all three children; two of them also had hypothermia. Furthermore all children had elevated blood ammonia levels, one child in combination with increased liver transaminases and one with thrombocytopenia.

RESULTS

All children recovered completely after discontinuation of VPA or TPM.

CONCLUSIONS

TPM seems likely to enhance the risk of side effects usually attributed to VPA and not described in TPM monotherapy. Our case reports suggest that possible adverse effects of VPA should be given particular attention when VPA is combined with TPM.

Idiosyncratic reactions: new methods of identifying high-risk patients

This article describes the mechanisms of idiosyncratic drug reactions (IDRs) and provides an analysis of potential methods for identifying patients at high risk for antiepileptic idiosyncratic drug reactions. IDRs may be caused by toxic metabolites, either directly or indirectly (by way of an immunologic response or a free radical-mediated process). Four methods to potentially identify patients at high risk for AED IDRs are discussed: development of an "at-risk" clinical profile for a particular AED: identification of biomarkers that measure the formation of a toxic metabolite by a previously unrecognized bioactivation pathway for a particular AED; identification of biomarkers indicating deficient detoxification abilities [e.g., deficient free radical scavenging enzyme activities or low calculated oxidative protection (COP) ratios 1 and 2]; and identification of at-risk genetic markers. Clinical profiles for patients receiving valproic acid (VPA), felbamate (FBM), and lamotrigine (LTG) and who are at risk for development of AED IDRs are presented. Patients with VPA IDRs have deficient erythrocyte glutathione peroxidase activity, low plasma selenium concentrations, low COP1 ratios, and low COP2 ratios compared with age-matched controls. Patients with FBM-associated aplastic anemia have deficient erythrocyte glutathione peroxidase, superoxide dismutase (SOD), and glutathione reductase activities compared with age-matched controls. Use of at-risk clinical profiles (for VPA, FBM, and LTG) and measurement of erythrocyte glutathione peroxidase activity, erythrocyte SOD activity, and calculation of COP1 and COP2 ratios (for VPA and FBM) are inexpensive, simple methods of identifying high-risk patients for IDRs. Research is needed to further characterize the mechanism of IDRs, to investigate the clinical utility of free radical-scavenging enzyme activity measurement and calculation of COP ratios for other AED IDRs, and to develop additional methods of identifying patients at high risk for AED IDRs.

Valproate and carbamazepine comedication changes hepatic enzyme activities in sera of epileptic children

Previous observation that valproic acid (VPA) and carbamazepine (CBZ) caused hepatic damage prompted us to investigate the effects of VPA or CBZ monotherapy and VPA + CBZ comedication on the number of hepatic enzyme activities in sera of epileptic children. This study compares alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyltransferase (GGT) activities in sera of children treated with VPA (n=42), or CBZ (n=36) taken as a monotherapy, with VPA + CBZ combined therapy (n=36). The effect of VPA alone is greater on the activity of AST than on other enzymes, while CBZ therapy changes primarily the activities of GGT. The mean catalytic activity of AST was significantly elevated in groups on VPA, CBZ and VPA + CBZ treatment (2.02-, 1.49- and 1.45-fold increase, respectively) as compared to the control values. Changes in the ALT activity followed different patterns. The maximal increase was observed in the CBZ group with a smaller increase in the group on VPA + CBZ polytherapy, whereas only 15% of patients receiving VPA showed an average 1.38-fold increase of the mean enzyme activity. Increase in the catalytic activity of GGT probably reflects the induction produced by the CBZ treatment, either alone or in combination. Children on CBZ monotherapy showed an increase of mean catalytic activity of about twofold in 56% of patients. Children on VPA + CBZ comedication showed a similar behaviour, while VPA alone produced a moderate (1.44-fold) increase in 23% of children. However, concentrations of VPA and CBZ in sera of patients receiving monotherapy were within the expected therapeutic limits, whereas subtherapeutic levels of VPA were found in 30% of children on VPA + CBZ comedication. We propose that individual dosage adjustment in VPA + CBZ polytherapy should be combined with monitoring of relevant enzyme activities in serum.

Management of chronic pain. Part I

Chronic pain is associated with substantial psychosocial and economic stress, coupled with functional loss and various levels of vocational dysfunction. The role of a pain center is to focus on chronic pain in a multidisciplinary, comprehensive manner, providing the patient with the most effective opportunity to manage his or her chronic disease syndrome. This article focuses on methods to manage many types of chronic pain and describes a broad range of pharmacologic and nonpharmacologic interventions and options available to the patient. Part I of this two-part monograph describes pharmacotherapeutic interventions and regional nerve blocks. Part II focuses on psychologic assessment and treatment and physical therapy. A multimodal management strategy offers patients the greatest improvement potential for specific chronic pain syndromes. Cognitive and behavioral therapies and physical therapies are described. This combination of therapies may provide patients with the skills and knowledge needed to increase their sense of control over pain. The integration of appropriate pharmacotherapeutic regimens, neural blockades, physical therapy, and psychologic techniques maximizes a patient's effectiveness in dealing with chronic pain. Three case studies are presented in Part II.

Hematologic manifestations and impaired liver synthetic function during valproate monotherapy

In a prospective study 50 children with new onset epilepsy were investigated. Routine screening for complete blood count, serum protein, albumin, gamma-glutamyltransferase (gamma-GT), aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase, and coagulation studies before, 3, 6 and 9 weeks after commencement of antiepileptic therapy with valproate were carried out. Serum B12 and folate levels were also determined in 29 patients. The aim of the study was to evaluate the effect of VPA on these laboratory findings. We found a significant reduction of red blood count and platelet count, whereas MCV showed a significant upward trend. Vitamin B12 levels were elevated after starting VPA therapy. We found no elevations of liver enzymes, but a significant transient reduction of ALT after 3 and 6 weeks and significantly reduced serum protein and albumin after 3, 6 and 9 weeks. Coagulation studies revealed a significant downward trend in serum fibrinogen and upward trend in thrombin time. The other parameters showed no significant changes after onset of VPA treatment. We think that reduced red blood cell and platelet counts, and elevated MCV indicate a direct toxic effect on a hematopoietic precursor or stem cell in patients treated with VPA. Furthermore, reduced protein, albumin and fibrinogen indicate an impaired liver synthetic function in asymptomatic children treated with VPA monotherapy.

Trans-2-ene-valproic acid is less behaviorally teratogenic than an equivalent dose of valproic acid in rats

Although animal experiments have shown the trans-2-ene metabolite (t-2-ene-VPA) of valproic acid (VPA) to be pharmacologically equivalent to the parent compound in terms of anticonvulsant activity, it is considerably less teratogenic in studies which have examined prenatally exposed fetuses for morphological defects. This has made t-2-ene-VPA an attractive potential antiepileptic agent. However, while neurobehavioral alterations have also been observed in rats prenatally exposed to VPA, even at doses below those which produce malformations, the developmental neurotoxicity of t-2-ene-VPA had not previously been examined. The current study evaluated the long-term behavioral effects of prenatal exposure to t-2-ene-VPA. Pregnant CD rats were treated with 300 or 400 mg/kg t-2-ene-VPA by gavage on days 7-18 of gestation, doses previously shown to produce no teratogenicity. A VPA group was administered 300 mg/kg for comparison. The pharmacokinetic profiles of the two compounds were similar. Behavioral findings in offspring prenatally exposed to VPA were consistent with previous findings, i.e., VPA offspring exhibited decreased locomotor activity, increased swimming maze errors, and reduced tactile startle responding compared to controls. In the 400 mg/kg t-2-ene-VPA group, Cincinnati maze errors and auditory startle reactivity were increased, while no significant behavioral effects were detected in the 300 mg/kg t-2-ene group. These results indicate that the developmental neurotoxicity of t-2-ene-VPA is lower than that of VPA but is still significant.

Hematologic manifestations of long-term valproate therapy

Sixty patients receiving long-term valproate (VPA) monotherapy were studied for hematologic side effects. All were patients in a long-term care facility and ranged in age from 2 to 29 years (mean 14.6 years). Twenty developed at least one prominent hematologic abnormality. Thrombocytopenia and macrocytosis were the most common findings. In patients with macrocytosis, platelet counts were inversely related to VPA levels. Serum B12 levels were increased in 51 of the patients. In 12 patients with macrocytosis who were extensively studied, no etiology for the increased MCV could be identified. An increased number of Pelger-Huet-like cells was noted in these 12 patients. None of the patients demonstrated hepatic dysfunction. Hematologic toxicity was never severe enough to discontinue therapy and always responded to small decrements in VPA therapy. VPA was discontinued in only 1 patient, owing to poor seizure control.

The rapid change to monotherapy with valproic acid in children

A review of hospitalized epilepsy patients at Texas Tech University identified 20 children during a 4-year period who had undergone a rapid change from other anticonvulsants to valproate monotherapy. All patients had difficult-to-treat or intractable epilepsy syndromes. In each case, sodium valproate was introduced over a 2- to 4-day period as all other anticonvulsants were withdrawn quickly and sequentially. No acute side effects were seen during hospitalizations, and only one patient reported gastrointestinal complaints. At time of discharge, 12 of the 20 patients were seizure free. Fifteen of the 20 patients were maintained on monotherapy following discharge. By the end of the study period, 12 of the 20 patients showed improvement with valproate, with nine patients experiencing complete seizure control. A rapid switch to valproate monotherapy can be done safely in an inpatient setting.

Valproate-induced coma: case report and literature review

OBJECTIVE

To report a case of hyperammonemia without hepatic dysfunction as a possible cause of lethargy, stupor, and coma in a woman after valproic acid (VPA) administration, and discuss the possible different mechanisms of ammonia elevation and coma.

CASE SUMMARY

A woman diagnosed with complex partial seizures that secondarily generalize was treated with phenytoin (PHT) 250 mg/d for 18 years. Three months before admission, this dosage was increased to 300 mg/d and phenobarbital (PB) 100 mg/d was added because the seizures were incompletely controlled. The patient developed a progressive inability to walk. She was diagnosed as having PHT intoxication. VPA therapy was begun while PHT was being tapered and progressive impairment of consciousness occurred. This evolved into a coma without focal neurologic signs, and was accompanied by isolated hyperammonemia without hepatic failure.

DISCUSSION

Adverse effects attributable to VPA were reviewed in the literature. Occasionally, VPA may lead to severe secondary effects such as hepatic failure and coma. In these cases increased blood concentrations of transaminases, bilirubin, and ammonia have been found. Several reports have stressed the existence of hyperammonemic coma without biochemical evidence of hepatic failure, which is what occurred in our patient. This suggests that isolated hyperammonemia and hepatic failure after VPA treatment may have a different biochemical basis.

CONCLUSIONS

VPA-induced coma with hyperammonemia and without evidence of hepatic failure should be considered in patients being treated with PHT or PB when VPA is administered concomitantly. This case report shows the importance of clinical monitoring and immediate drug discontinuation when drowsiness, gastrointestinal symptoms, or lethargy occur.

Valproate (VPA) metabolites in various clinical conditions of probable VPA-associated hepatotoxicity

Of a cohort of 470 epileptic patients in whom valproate (VPA) serum metabolites had been measured, 170 subjects without symptoms or signs of hepatic side effects were chosen as a reference group to establish the usual metabolic pattern. A wide interindividual variation of VPA metabolite concentrations was noted. Infants receiving VPA monotherapy and comedication with other antiepileptic drugs (AEDs) showed lower concentrations of the potential hepatotoxin 4-ene-VPA than did older children. In 11 patients with early symptoms and signs of possible fatal VPA-associated hepatotoxicity, the following spectrum of benign clinical conditions was observed: unusually severe side effect during initiation of VPA therapy (1 patient), high VPA dosage (2 patients), reversible impairment of coagulation with bleeding manifestations in association with a slight increase in transaminase levels (1 child), and reversible liver dysfunction associated with febrile illness (7 patients). Reversible or irreversible fulminant liver failure had occurred in 5 children. Three of the 4 children with a fatal outcome had massive lactic acidosis. In all patients with probable VPA-associated hepatotoxicity, some aspects of VPA metabolism differed distinctly from that of the reference group, but the inter-individual profile of metabolites varied considerably, even in the subgroup of 4 children who died. Impairment of VPA beta-oxidation and increase of metabolites of alternative metabolic pathways (omega- and omega 1-hydroxylation, dehydrogenation reactions) were the most frequent findings. Increased values of 2-n-propyl-4-pentenoic acid metabolite of VPA (4-ene-VPA), could be detected only in 1 of the 5 patients with fulminant liver failure and in one other child with a slight hepatic dysfunction, indicating that this VPA metabolite is not the decisive hepatotoxin or indicator of hepatotoxicity. Because we cannot distinguish between benign and life-threatening hepatic adverse reactions on the basis of VPA metabolites, all identified changes are considered secondary to an as-yet-unknown primary metabolic event. The most toxic compound could be VPA itself, which may unmask an inborn or an acquired metabolic defect in the processing of fatty acids.

Effects of valproate and E-2-en-valproate on functional and morphological parameters of rat liver. I. Biochemical, histopathological and pharmacokinetic studies

E-2-en-Valproate (E-2-en-VPA; trans-2-en-VPA) and VPA were studied for potential hepatotoxicity in young male Sprague-Dawley rats. Both drugs were administered daily at 750 mg/kg i.p. (divided into three doses a day) for 7 consecutive days. Clinical chemistry parameters were studied before and after the period of treatment. Furthermore, the drug pharmacokinetics and metabolism were analyzed at onset and end of the prolonged administration. Treatment with VPA induced hyperammonemia and other alterations in liver function tests which were not observed after treatment with E-2-en-VPA, although plasma levels of both drugs were comparable. The pharmacokinetics of VPA and E-2-en-VPA in young rats were similar, but analysis of metabolites by gas chromatography-mass spectrometry indicated marked differences in the metabolite profile, e.g., a lack of the suspected hepatotoxic metabolite 4-en-VPA in plasma of rats treated with E-2-en-VPA. Histopathological examination of liver sections showed that VPA and E-2-en-VPA did not induce degenerative liver lesions or significant alterations in hepatic content and distribution of lipids and glycogen at the doses administered. Only one of the VPA treated rats showed fatty infiltration (microvesicular steatosis). The data demonstrate that, although E-2-en-VPA is more potent than VPA as an anticonvulsant in rats, it does not exert more potent hepatotoxic effects and does not alter ammonia metabolism. Thus the data substantiate previous experimental studies that E-2-en-VPA might be a valuable substitute for VPA.

Liver function tests in persons receiving anticonvulsant medications

Liver function tests were carried out in 206 adults and children taking anticonvulsants to ascertain the prevalence of biochemical abnormalities in asymptomatic patients. It was observed that serum gamma-glutamyl transpeptidase was elevated in 74.6% of patients, alkaline phosphatase in 29.7% and alanine aminotransferase in 25.2% of cases. These figures are similar to those previously reported in the literature and probably reflect hepatic enzyme induction by the anticonvulsants. It is suggested that there is no value in the routine performance of liver function tests in patients with epilepsy. However, such patients should be informed of the symptoms of hepatic dysfunction and asked to report for liver function tests should they have such symptoms.

Valproate hepatotoxicity syndrome: hypotheses of pathogenesis

Therapeutic use of the anticonvulsant valproate (VPA) has been associated with a rare, but severe and often fatal hepatotoxicity. Cases usually present with lethargy, anorexia, and vomiting with rapid progression to coma. Liver histopathology is characterized by steatosis with and without necrosis. In some instances only necrosis was present. Several hypotheses of pathogenesis have been postulated. These deal mainly with biochemical systems that are known to be affected by VPA, or with the possible idiosyncratic production of toxic VPA metabolites, especially delta 4-VPA. At present, no hypothesis entirely explains the diverse characteristics of the disorder.

Identification of the main metabolites of 2-ethylhexanoic acid in rat urine using gas chromatography-mass spectrometry

The metabolites of 2-ethylhexanoic acid, an industrial chemical and the active ingredient in wood preservatives, were investigated in rat urine. Male Wistar rats were given 2-ethylhexanoic acid (2-EHA) in drinking water (600 mg/kg daily) for nine weeks, and then urine specimens were collected and analysed. The compounds were identified by gas chromatography-mass spectrometry in both electron-impact mode and chemical ionization mode. In addition to 2-EHA, ten different 2-EHA-related metabolites were found in the urine of 2-EHA-treated rats. The main metabolite was 2-ethyl-1,6-hexanedioic acid. Urine also contained 2-ethyl-6-hydroxyhexanoic acid and five other hydroxylated metabolites and two lactones, the detailed structures of which have not yet been elucidated. The unsaturated 5,6-dehydro-EHA was also identified; this is the metabolite corresponding to 2-n-propyl-4-pentenoic acid, the hepatotoxic metabolite of valproic acid. At least part of the 2-EHA is present in urine as a glucuronide conjugate.

Valproic acid hepatotoxicity in human liver slices

Precision cut human liver slices were incubated in organ culture with valproic acid (VPA) to identify patterns of sensitivity to VPA-induced hepatotoxicity. The slices were incubated in Krebs-HEPES buffer supplemented with 25mM glucose and 84 micrograms/ml gentamycin. At 2, 4, 6, 12, 18 and 24 hr slices were taken and analyzed for K+ retention, synthesis of protein and LDH leakage. All three of these viability indicators showed that certain human livers were more susceptible to VPA-induced hepatotoxicity than others. In the limited group of human livers investigated (n = 9) we found one to be particularly sensitive and two relatively insensitive to VPA toxicity. The remaining tissues were of intermediate sensitivity towards VPA. At this time there is no correlation between the human livers that were susceptible to VPA induced hepatotoxicity and age or sex. This study was designed to show that VPA does induce hepatotoxicity in vitro at therapeutically relevant concentrations. Future studies will show whether VPA hepatotoxicity correlates with VPA metabolism, nutritional status or concomitant therapy.

Valproate, carnitine metabolism, and biochemical indicators of liver function. Collaborative Group for the Study of Epilepsy

The effects of valproate (VPA) on carnitine and lipid metabolism and on liver function were assessed in 213 age- and sex-matched outpatients from five centers, with the following distribution: VPA monotherapy, 54; VPA polytherapy, 55; other monotherapies, 51; and untreated, 53. Mean total and free carnitine levels were significantly lower in patients with polytherapy; acylcarnitine was significantly higher for VPA monotherapy and the ratio of acyl- to free carnitine was significantly higher in all patients receiving VPA. Ammonia, uric acid, and bilirubin were the only tests selectively impaired with VPA. A significant correlation was found between serum ammonia and VPA dosage. Glucose, beta-lipoproteins, triglycerides, acetacetate, and beta-hydroxybutyrate were unchanged in the four groups. Sex and age appeared to interact with total and free carnitine values. Adverse drug reactions were apparently unrelated to carnitine metabolism impairment. Only a few patients had abnormal carnitine values. Our data support the assumption that carnitine deficiency and abnormal liver function due to VPA are mostly subclinical events.

Physiologic and metabolic aspects of anticonvulsants

A great number of anticonvulsants are available for treating these different types of epilepsy. Therapeutic drug monitoring has been favored as the method for controlling drug concentrations in the plasma and preventing untoward effects. When these anticonvulsants are prescribed to treat epilepsy in children, careful monitoring is most important because drug metabolism varies depending on maturation and development of body functions. Molecular approaches are also important to elucidate the effectiveness of the drugs for treatment of different seizure disorders and should contribute to a better understanding of body functions.

Facial clefts and congenital heart defects in children of parents with epilepsy: genetic and environmental etiologic factors

Increased prevalence of cleft lip with or without cleft palate (CL(P], isolated cleft palate (CP), and congenital heart defects (CHD) in children of epileptic mothers have been ascribed to early fetal exposure to antiepileptic drugs (AED). However, common genetic factors responsible for both the malformations in question and the epileptic disorder might be of relevance for the increased rate of CL(P), CP, and CHD, rather than the influence of AED. The present review analyzes the literature on genetic and environmental etiologic factors (i.e. AED and epileptic seizures) that have been reported to increase the rate of CL(P), CP, and CHD in children of parents with epilepsy. Our data suggest that genetic factors are of minor importance for the etiology of facial clefts in offspring of epileptic patients. The rate of facial clefts was increased by a factor of 4.7 in children of AED-treated mothers with epilepsy compared with the background population values. Children of fathers with epilepsy and sibs of epileptic patients had no more facial clefts than expected. The rate of CHD in children of mothers and fathers with epilepsy was comparable to population figures. The role of epileptic seizures as a causative factor for CL(P), CP, and CHD is not settled, but seems to be of limited importance. Areas of future research are outlined concerning the teratogenic role of AED and their metabolites, especially on the postnatal intellectual development of the exposed children. Finally, the need for studies on prophylactic measures as well as the necessity of international surveillance systems on new AED teratogenicity are emphasized.

Clinical pharmacokinetics of valproic acid--1988

Sodium valproate (valproic acid) has been widely used in the last decade and is now considered a relatively safe and effective anticonvulsant agent. Recently, several investigators have proposed its use in the treatment of anxiety, alcoholism and mood disorders, although these indications require further clinical studies. Valproic acid is available in different oral formulations such as solutions, tablets, enteric-coated capsules and slow-release preparations. For most of these formulations bio-availability approaches 100%, while the absorption half-life varies from less than 30 minutes to 3 or 4 hours depending on the type of preparation used. Once absorbed, valproic acid is largely bound to plasma proteins and has a relatively small volume of distribution (0.1 to 0.4 L/kg). Its concentration in CSF is approximately one-tenth that in plasma and is directly correlated with the concentration found in tears. At therapeutic doses, valproic acid half-life varies from 10 to 20 hours in adults, while it is significantly shorter (6 to 9 hours) in children. Valproic acid undergoes extensive liver metabolism. Numerous metabolites have been positively identified and there is reasonable evidence that several of them contribute to its pharmacological and toxic actions. In fact, several valproic acid metabolites have anti-convulsant properties, while many of the side effects it may cause (e.g. those related to hyperammonaemia or liver damage) are most often observed in patients previously treated with phenobarbitone. This could indicate that induction of liver enzymes is responsible for the formation of toxic valproic acid metabolites.

Valproate metabolites and hepatotoxicity in an epileptic population

Idiosyncratic hepatotoxicity, although rare, is of major concern when one is treating patients with valproate (VPA). Several clinical criteria are associated with an increased risk of developing this complication, but more specific predictors are needed. It has been postulated that 4-en-VPA or one of its further metabolites may be responsible for the hepatic toxicity and that under certain conditions the metabolism of VPA is shifted to this product. We postulated that measurement of serum concentrations of 4-en-VPA or another metabolite might be a simple technique that would be predictive of risk for developing idiosyncratic hepatotoxicity. Because this complication is rare, we chose to analyze our data by a multiple linear regression model, exploring associations between VPA or three of its metabolites and clinical risk factors for hepatotoxicity. 4-en-VPA correlated with older age and absence of encephalopathy. 4-en-VPA was only seen in patients receiving polytherapy; all patients were also receiving CBZ. 2-en-VPA correlated with poor nutritional status. We conclude that routine measurement of serum 4-en-VPA is unlikely to be a useful predictor of risk for developing fatal hepatotoxicity. Serum concentrations of 4-en-VPA may not reflect presence or effects in the liver as it may be metabolized to further intermediates or be bound to tissue. Thus, serum levels of 4-en-VPA do not reflect its important role in the pathogenesis of hepatotoxicity. This metabolite was detected only in patients receiving polytherapy, a potent risk factor for developing this rare complication.

Fatal liver failure in 16 children with valproate therapy

The data of 16 children who died while receiving valproate (VPA) therapy in West Germany were analyzed. Five were normally developed, 5 were receiving VPA-monotherapy, and only 2 patients were aged less than 3 years. The first clinical symptoms of impending hepatotoxicity usually included nausea, vomiting, and apathy; pathologic laboratory tests reflected liver failure. Liver histology revealed microvesicular steatosis, cell necrosis, and bile duct proliferation of varying degree. An abnormal metabolite, 4-ene-VPA, was detected in all examined patients (six of six) and persisted after drug withdrawal. The pathogenesis of fatal liver failure during VPA treatment remains unknown. World-wide, approximately 100 fatalities have been reported in relation to VPA treatment. More than 90% were aged less than 20 years, 95% developed their first symptoms within the first 6 months of treatment, and 16 were treated with VPA alone. Since it is difficult precisely to define a group at risk for fatalities with VPA, careful clinical and laboratory monitoring with a special focus on vomiting and apathy, liver enzymes, and coagulation tests seem mandatory during the first 6 months after introduction of VPA. Taking into account the considerable number of fatalities during VPA treatment, the indication for its use requires careful reevaluation.

Three cases of delivery under sodium valproate--placental transfer, milk transfer and probable teratogenicity of sodium valproate

Here is a report of three cases of delivery from women who have taken sodium valproate (VPA). One neonate was born with polydactylism, and we reviewed the congenital malformations in children of mothers who have taken VPA. In the other two cases, we also examined the levels of VPA in the cord serum and breast milk. The levels of VPA in the cord serum were 50 micrograms/ml at 12 hours after the last maternal dose and 75 micrograms/ml at 14 hours after the last maternal dose. The blood levels of VPA in the two mothers were 48-59 micrograms/ml and 55-85 micrograms/ml in their late pregnancy, respectively. The levels of VPA in the breast milk were 2.0-3.5 micrograms/ml and the ratio of VPA in the breast milk to blood was 2-3%. These results suggest the high rate of placental transfer and the low rate of milk transfer of VPA.

Progressive neuronal degeneration of childhood (PNDC) with liver disease

Thirteen children with progressive neuronal degeneration and liver disease are reported. Clinical features included developmental delay after a normal initial period with later onset of intractable epilepsy. The EEG showed an unusual but characteristic pattern, and visual evoked responses (VER) were abnormal. Rapidly progressive cerebral atrophy was seen on computerized axial tomography (CAT). Inheritance was consistent with an autosomal recessive trait. Pathological findings were neuronal degeneration and spongy change of the cerebral cortex. The calcarine cortex was more severely affected than other areas. Hepatic lesions included severe fatty change and cirrhosis. In six patients liver disease was detected before the onset of epilepsy and exposure to anticonvulsants. Two others were reported to have died from sodium valproate (SV) toxicity, but both had abnormal liver enzymes before treatment with SV, and in both the neuropathological findings were indicative of PNDC. During life, PNDC may be indicated by the characteristic clinical course, abnormal liver function tests, and abnormalities of EEG, VER, and CAT.

New anticonvulsants in pediatrics: carbamazepine and valproate

The majority of patients with epilepsy have their first seizure during childhood and are first evaluated and diagnosed by their pediatrician. For many patients the medication selected by the pediatrician will be taken for an extended time period, perhaps even for a lifetime. The first job of the pediatrician is to be sure that the patient's recurrent attacks represent genuine epilepsy and not some other paroxysmal medical disorder such as migraine or cardiac arrhythmias. Epileptic seizures are then classified by a careful clinical description of the attacks in conjunction with the results of the physical and EEG examinations. Based on all of the information at hand, the clinician chooses the drug that is most likely to reduce or eliminate further seizures without exposing the child to unnecessary medical risk or behavioral-cognitive adverse effects. In properly selected patients, both carbamazepine and valproate are safe, physically well tolerated, and less likely to provoke chronic mental side effects than the pediatrician's "traditional" choices: phenobarbital or phenytoin. Although carbamazepine and valproate have been widely acclaimed by neurologists and epileptologists, practicing pediatricians have heretofore been less likely to initiate treatment with these drugs. Yet pediatricians have something of priceless value to offer the child with epilepsy: seizure control and a clear mind. The information in this monograph should assist the practicing pediatrician in the rational choice, initiation, and follow-up of treatment with these two excellent anticonvulsants.