Evaluation of valproate effects on acylcarnitine in epileptic children by LC-MS/MS

Background: Valproate (VPA) is a simple fatty acid and a substrate for the fatty acid β-oxidation pathway. Previous data suggested that the toxicity of VPA may be provoked by carnitine deficiency and the inhibition of mitochondrial β-oxidation. Objective: The aim of the present study was to elucidate the effect of VPA treatment on carnitine and isomer-differentiated acylcarnitine disposition, and determined the relationships between acylcarnitines and blood VPA levels in long-term treated patients with VPA and/or other antiepileptic drugs. Methods: Serum samples were obtained from children aged 1-15 years old treated for at least 6 months with VPA alone (n = 28) or VPA combined with other anticonvulsants (n = 23) and untreated controls (n = 23). Serum acylcarnitines were separated from their isomers and quantified using high-performance liquid chromatography-tandem mass spectrometry. Results: We found higher 3-hydroxyisovalerylcarnitine levels and trace amounts of valproylcarnitine in both VPA monotherapy and polytherapy patients. Other acylcarnitines, hexanoylcarnitine, C12, C14:1-carnitines and the ratio of long-chain acylcarnitine to free carnitine were also higher in VPA polytherapy individuals than in controls. VPA monotherapy does not result in decreases in free carnitine or in the accumulation of long-chain acylcarnitines. Blood VPA concentrations correlated positively with hexanoylcarnitine, C12, C14:1, C16:1, C18:1-carnitines in all VPA-treated children (n = 51). Conclusion: Long-term VPA treatment in pediatric patients could affect some specific acylcarnitines, which is enhanced by the concomitant use of other anticonvulsants, and the formation of valproylcarnitine alone seems insufficient to develop severe carnitine deficiency at therapeutic doses of VPA.     

Effect of L-Carnitine Supplementation on Acute Valproate Intoxication

Summary: We analyzed urinary valproate (VPA) metabolites and carnitine concentrations in a child who accidentally ingested 400 mg/kg VPA. The concentration of 4-en VPA, the presumed major factor in VPA-induced hepato-toxicity, was markedly increased, without liver dysfunction or hyperammonemia. The other major abnormality was decreased β-oxidation and markedly increased ω-oxidation. After L-carnitine supplementation, VPA metabolism returned to normal. The level of valproylcarnitine was not increased and therefore was not affected by L-carnitine. L-Carnitine may be useful in treating patients with coma after VPA overdose.     

Comparison of the Steady-State Pharmacokinetics of Topiramate and Valproate in Patients with Epilepsy During Monotherapy and Concomitant Therapy

Summary: Purpose: The steady-state pharmacokinetics of valproate (VPA) and topiramate (TPM) were compared during VPA monotherapy, concomitant VPA and TPM therapy, and TPM monotherapy to evaluate pharmacokinetic interactions. Methods: After a 3-week baseline period, 12 patients receiving VPA monotherapy (500 to 2,250 mg every 12 h) received TPM at three escalating doses (from 100 to 200 to 400 mg every 12 h), each for 2 weeks. Thereafter, the VPA dose was tapered by 25% weekly. Blood and urine samples were collected over 12-h intervals during VPA monotherapy and at the end of each stage of TPM dose escalation and TPM monotherapy. Results: All patients reached TPM monotherapy, and nine achieved satisfactory seizure control for 2 weeks without VPA. TPM plasma peak concentration (C_max) and area under the concentration-versus-time curve during a 12–h dosing interval (AUC_0–12) were slightly higher (17%; n = 8) during TPM monotherapy than during concomitant VPA therapy. TPM oral and renal clearances (n = 8) were 25.9 ± 4.6 and 11.6 ± 3.2 ml/min during TPM monotherapy and were 29.8 ± 4.2 and 12.4 ± 2.7 ml/min during VPA concomitant therapy. VPA AUC_(0–12) decreased (11.3%; n = 10) with the addition of TPM 400 mg every 12 h. VPA oral clearance was 12.8 ± 4.1 ml/min during monotherapy and was 13.8 ± 4.0,14.1 ± 3.9, and 14.5 ± 5.2 ml/min during coadministration of TPM 100, 200, and 400 mg every 12 h, respectively. Cognitive dysfunction, observed in some patients receiving high doses of VPA with TPM, reversed or improved with VPA dose reduction and discontinuation. The lower-than-normal prestudy platelet count measured in one patient increased to normal levels when VPA was discontinued. Conclusions: Because changes in TPM and VPA pharmacokinetics were small, it is unlikely that their concomitant use will have a significant impact on the clinical condition of the patient.     

Clinical trial of L‐Carnitine and valproic acid in spinal muscular atrophy type I

Introduction: The aim of this study was to determine the safety and therapeutic potential of L ‐carnitine and valproic acid (VPA) in infants with spinal muscular atrophy (SMA). Methods: Our investigation was an open‐label phase 2 multicenter trial of L ‐carnitine and VPA in infants with SMA type I with retrospective comparison to an untreated, matched cohort. Primary outcomes were: safety and adverse events; secondary outcomes were survival, time to death/>16 hours/day of ventilator support; motor outcomes; and maximum ulnar compound motor action potential amplitude. Results: A total of 245 AEs were observed in 35 of the 37 treated subjects (95%). Respiratory events accounted for 49% of all adverse events, resulting in 14 deaths. Survival was not significantly different between treated and untreated cohorts. Discussion: This trial provides evidence that, in infants with SMA type I, L ‐carnitine/VPA is ineffective at altering survival. The substantial proportion of infants reaching end‐points within 6 months of enrollment underscores the urgent need for pre‐symptomatic treatment in SMA type I. Muscle Nerve 57 : 193–199, 2018     

Carnitine levels in valproic acid-treated psychiatric patients: a cross-sectional study

BACKGROUND: Carnitine facilitates the transport of long-chain fatty acids across the mitochondria for beta oxidation, and the removal of potentially toxic acylcoenzyme-A metabolites from the inner aspect of mitochondrion as acylcarnitines. Previous studies suggest a significant decrease in carnitine concentrations and changes in the ratio of acylcarnitine to free carnitine in seizure-disoriented patients treated with valproic acid (VPA), which may lead to clinical manifestations of carnitine deficiency. This study sought to explore whether the same decrease in plasma free carnitine and increase in acylcarnitines are seen when VPA is used in the treatment of patients with psychiatric disease. METHOD: Thirty psychiatric patients treated with VPA for at least six months were selected for the study and granted informed consent for participation. Exclusion criteria included liver disorder or pancreatitis, metabolic defects known to affect plasma carnitine levels, or noncompliance with VPA regimen. Plasma free carnitine, total carnitine, VPA, and amylase levels were determined, and liver function tests (LFTs) were performed. Pearson correlations were conducted between VPA levels, levels and ratios of carnitines, as well as LFTs and amylase levels. RESULTS: Plasma free and total carnitine levels were lower than the reported normal range for the laboratory performing the assay, and the ratio of acylcarnitine to free carnitine was increased. There was a significant positive correlation of VPA levels and acylcarnitine-free carnitine ratio, a trend toward significance between VPA levels and acylcarnitine levels, and a marginal negative correlation between VPA levels and free carnitine levels. VPA levels correlated also with several LFTs and acylcarnitine levels. Octanoyl carnitine and acylcarnitine levels, as well as acylcarnitine-free carnitine and octanoyl-free carnitine ratios, correlated significantly with amylase levels. CONCLUSION: Although the study was limited by a cross-sectional design without direct control comparison, the findings suggest that patients with various psychiatric conditions treated with polypharmacy that includes VPA may have lower plasma carnitine levels than would be expected in healthy controls.     

Effects of acute valproic acid administration on carnitine plasma concentrations in epileptic patients

Serial plasma samples collected after an acute administration of valproic acid, (VPA, 15 mg/kg as oral solution) in epileptic patients were selected for this study. The plasma samples were selected from three different groups of patients; patients on phenobarbital and phenytoin with clinical VPA intolerance (group A); patients on phenobarbital and phenytoin without clinical VPA toxicity (group B); and patients without phenobarbital and phenytoin and without clinical VPA toxicity (group C). Plasma samples from 6 patients per group were analyzed for carnitines and ammonia. Ammonia levels during acute study increased significantly (P less than 0.05) in patients who experienced VPA intolerance, while no changes were found in the other patients. After acute VPA administration, total carnitine was unchanged but free carnitine was decreased (P less than 0.05) and carnitine esters were increased (P less than 0.05) in all groups of patients studied. No difference in carnitine profiles was seen between patients with or without evidence of VPA administration has an important effect on carnitine metabolism. However, unlike the acute effect on ammonia metabolism, this acute effect does not seem to be correlated with any associated antiepileptic therapy, nor does it predict clinical VPA intolerance.     

The prevalence of valproic-acid-associated hyperammonaemia in patients with intractable epilepsy resident at the Chalfont centre for epilepsy

Valproic acid (VPA)-induced hyperammonaemia, with or without clinical or laboratory evidence of hepatoxicity, is well-documented. This study was designed to assess the prevalance of hyperammonaemia in institutionalised patients treated with VPA chronically and to identify contributing factors. Eight-two refractory patients (60 men and 22 women; mean age, 39 years; mean weight, 70.1 kg), were studied. Ten patients were on VPA monotherapy, and 72 were on antiepileptic drug (AED) polytherapy. Fourteen epileptic patients on AED polytherapy excluding VPA (patient controls) and 10 volunteers (healthy controls) were also evaluated. VPA dose ranged between 7.1 and 71.4 mg/kg/day and was associated with VPA plasma concentrations of 114–753 and 77–1,315 μmol/L pre-and postprandially, respectively. A plasma ammonium (NH₄⁺) concentration of 50 μmol/L is considered the upper normal limit in healthy adult subjects. Pre- and postprandial plasma NH₄⁺ concentrations >50 μmol/L were seen in 20% and 30% of VPA-treated patients, respectively. In contrast, all healthy and patient controls had plasma NH₄⁺ concentrations <50 μmol/L. VPA dose correlated significantly with VPA plasma concentration only in the monotherapy group and with postprandial plasma NH₄⁺ concentration. The highest VPA dose (71.4 mg/kg/day) was associated with the highest (95 μmol/L) plasma NH₄⁺ concentration. There was a significant correlation (r = 0.61; p < 0.02) between plasma NH₄⁺ and VPA concentration postprandially in male patients taking VPA and carbamazepine in combination. It is concluded that, although VPA medication can be associated with elevated plasma NH₄⁺ concentrations that are not clinically significant in many patients, caution is necessary when prescribing VPA.     

Carnitine Disposition Before and During Valproate Therapy in Patients with Epilepsy

Summary: Free and total carnitine and acylcarnitine in plasma and urine samples was measured in 22 epileptic patients before and after 15 and 45 days of valproate (VPA) therapy and in 16 healthy volunteers on a single occasion. Carnitine plasma concentration and renal excretion observed in epileptic patients before VPA therapy did not differ from control values. After VPA was started, free and total plasma concentration decreased significantly (p < 0.05) from 49 ± 17 to 35 ± 16 at 15 days and to 35 ± 13 nmol/ml at 45 days of therapy (free carnitine) and from 60 ± 18 to 50 ± 18 at 15 days and to 55 ± 14 nmol/ml at 45 days of therapy (total carnitine), whereas acylcarnitine increased significantly (p < 0.05) from 10 ± 8 to 14 ± 8 at 15 days and to 18 ± 16 nmol/ml at 45 days of therapy. Free carnitine urinary excretion decreased significantly (p < 0.05) from 200 ± 135 to 115 ± 76 and 118 ± 75 μmol/24 h, whereas acylcarnitine urinary excretion increased significantly (p < 0.05) from 78 ± 56 to 154 ± 98 and 155 ± 89 μmol/24 h after VPA therapy was started. As a consequence, acylcarnitine renal clearance increased significantly (+ 30%, p < 0.05) whereas free carnitine renal clearance did not change during VPA therapy. No difference was detected between 15 and 45 days of therapy. No patients experienced symptoms of VPA toxicity. Our results suggest that VPA in patients increases both formation and renal clearance of acylcarnitine.     

Diet- and valproate-induced transient hyperammonemia: effect of l-carnitine

Hyperammonemia is an adverse effect of valproate (VPA) treatment. In particular, transient hyperammonemia has been reported to occur in VPA-treated patients after protein-rich meals. This phenomenon may occur secondary to a VPA-mediated carnitine insufficiency. We sought to confirm that protein ingestion would result in transient hyperammonemia and to determine whether supplementation with -carnitine would prevent this effect. We studied the effect of consumption of a standardized protein-rich meal (45 g protein) before (phase I) and after (phase II) administration of -carnitine 50 mg/kg/day for 7 days in 11 epileptic children (13.3 ± 2.3 years of age) receiving VPA. Venous blood was obtained during fasting (baseline) and at 2 and 4 hours after the protein-rich meal for analysis of ammonia (NH₃), and VPA concentrations. Mean VPA trough concentrations did not differ significantly at any time. After protein ingestion, 2-hour NH₃ concentration increase by 86% (P < .05) from baseline in phase I as compared with a 38% increase in phase II. In both phases I and II, 4-hour NH₃ concentrations decreased toward baseline values. We conclude that (1) modest protein ingestion can result in significant transient increases in NH₃ in VPA-treated children, (2) significant increases may occur in patients with normal fasting NH₃ concentrations, (3) these increases can be significantly attenuated by -carnitine supplementation, and (4) these changes do not appear to be related to changes in VPA concentration.     

Valproate Metabolites in High-Dose Valproate Plus Phenytoin Therapy

Summary: Purpose: We wished to determine the relation between liver function, β-, and ω-, and ω-1-oxidation metabolites and 4-en-valproate (VPA).
Methods: We measured the serum levels of VPA and its metabolites in children and adolescent receiving high-dose VPA plus phenytoin (PHT) therapy using gas chromatography-mass spectrometry with selected ion monitoring (GC/MS/SIM).
Results: In high-dose VPA plus PHT polytherapy, the total VPA serum concentration was distinctly low, the concentrations of total β -oxidation metabolites were decreased, the percentage values of VPA (percent of VPA) of total β -oxidation metabolites were increased, and the E-2-en-VPM3-keto-VPA ratios were decreased, as compared with those in high-dose VPA monotherapy. In high-dose VPA plus PHT polytherapy, 4-en-VPA (μ M ) was decreased and the concentrations of (ω+ (ω - 1)]-oxidation metabolites (μ M) were decreased as compared with those in high-dose VPA monotherapy. In high-dose VPA plus PHT, serum glutamic-oxaloacetic transarninase (GOT), glutarnic-pyruvic transaminase (GPT) and lactic dehy-drogenase (LDH) did not correlate significantly with the (β/ω+ (ω - 1) metabolites ratio and 4-en-VPA levels, but serum GOT, GPT, and LDH were increased as compared with those in high-dose VPA therapy. We were not able to establish a significant relation between the formation of metabolites of VPA metabolites and liver dysfunction in patients receiving high-dose VPA and PHT concurrently.
Conclusions: Metabolic levels do not appear to be a reliable predictor of hepatotoxicity in children receiving pharrnacological antiepileptic drug (AED) therapy.     

Abnormal metabolism of carnitine and valproate in a case of acute encephalopathy during chronic valproate therapy.

We analyzed the urinary metabolic profiles of valproate (VPA) and carnitine metabolism in an epileptic patient who died of acute encephalopathy during VPA therapy. On admission, the serum free carnitine level was greatly decreased and gas chromatographic mass spectrometric analysis of organic acids in urine showed a complete lack of beta-oxidation metabolites of VPA, while omega-oxidation was markedly increased. After administration of L-carnitine, the levels of acylcarnitine in both serum and urine, and of serum free carnitine increased, and the metabolites of beta-oxidation appeared in urine, while there was no improvement in the liver and renal functions. This is not a typical case of VPA-induced hepatotoxicity and the main cause of the disease is not clear. But the results show that the mitochondrial beta-oxidation of VPA was greatly disturbed in this patient, which may be related to the carnitine deficiency induced by the chronic VPA-therapy.     

Cerebral blood flow and oxygen uptake, and cerebrospinal fluid biochemistry in severe coma

Thirty-eight patients in coma due to head trauma, cerebrovascular accidents, hypoxia, hypoglycaemia, or barbiturate intoxication, and 15 cases of brain death were studied. Cerebral metabolic rate of oxygen (CMRO₂) was obtained from the arteriovenous oxygen difference and cerebral blood flow (CBF) measured by intra-arterial ¹³³Xenon method. If hypothermia and CNS depressants were excluded, CMRO₂ below one-third of normal was incompatible with regaining of consciousness, but this was seen in only three comatose patients. Irrespective of the clinical outcome (death, vegetative survival, or recovery), CMRO₂ values of one-third to two-thirds of normal were seen in the majority of coma patients. CMRO₂ measurements were of no practical value to predict the prognosis in coma, even when the effect of temperature and sedatives were considered. In brain death the CBF studies gave indirect evidence of cerebral circulatory arrest. The cerebrospinal fluid (CSF) was obtained for analysis of lactate, pyruvate, and bicarbonate in 29 cases. Increased CSF lactate levels were found in all groups except barbiturate intoxication. The finding of a negative correlation between CSF bicarbonate and log CBF suggests that the CSFpH determines the wide range of CBF in coma.     

Effects of Alpha- and Beta-Adrenergic Agonists and Antagonists on Growth Hormone Secretion in Man

It is well known that the adrenergic system has both stimulatory and inhibitory influences on growth hormone (GH) secretion probably by modulating GH-releasing hormone (GHRH) and/or somatostatin release. To better understand the mechanisms by which these influences take place, we investigated the effects of α- and β-adrenergic agonists and antagonists on both basal and GHRH-induced GH release in 23 male adult volunteers. The GH-releasing effect of clonidine (0.15 mg infused iv over 10 min), an α₂-adrenergic agonist, was significantly blunted by yohimbine (30 mg orally at ?50 min), a relatively specific α₂-adrenergic antagonist area under the response curve, mean±SEM: 672.6 ± 143.0 versus 219.6 ± 16.7 μg/l/h; P<0.05). On the other hand, the GHRH (1 μg/kg iv as a bolus)-induced GH increase was unaffected by yohimbine (339.3 ± 19.1 versus 518.1±172.8 μg/I/h). Concomitant blockade of α₁-/α₂-adrenoreceptors by phentolamine (0.5 mg/ml/min infused iv from ?60 to +30 min) abolished the GHRH-induced GH rise (645.5± 106.0 versus 189.0±58.8 μg/l/h; P<0.01). Finally, the GHRH-stimulated release was blunted by β₂-adrenergic stimulation with salbutamol (10 μg/min infused iv from ?5 to +15 min) (324.3 ± 99.7 versus 112.7 ± 48.8 μg/l/h; P<0.02). In conclusion: 1) The evidence that yohimbine is able to blunt the clonidine-induced GH release but fails to inhibit the GHRH-induced GH rise indicates that, as in animals, in man too the GH-releasing effect of clonidine is specifically mediated by α₂-receptor activation, and may occur via endogenous GHRH release; 2) the inhibitory effect on GH release of β, namely β₂, receptor activation is probably mediated by the somatostatinergic system; 3) an unopposed β-adrenergic activation would account for the inhibitory effect on GHRH-induced GH release of concomitant α₁–/α₂-adrenoreceptor blockade by phentolamine.     

Valproate, Carnitine Metabolism, and Biochemical Indicators of Liver Function

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.     

Do Structural Properties Explain the Anticonvulsant Activity of Valproate Metabolites? A QSAR Analysis

Summary: Purpose: Differences in potency among valproate (VPA) metabolites could be explained by structural properties. Therefore, a quantitative structure–activity relation (QSAR) analysis was performed to study the relation between structural parameters and the effect of the following VPA metabolites: 4‐en‐VPA, 2‐en‐VPA, 3‐en‐VPA, 2,4'‐dien‐VPA, 4,4'‐dien‐VPA, 4‐hydroxy‐VPA, 3‐ceto‐VPA, 3‐hydroxy‐VPA, 5‐hydroxy‐VPA, and propylglutaric acid. Methods: By using the CAChe program package for biomolecules (Oxford Molecular, Ltd), we performed molecular modeling. The anticonvulsant activity determined on the threshold for maximal electroconvulsions in mice was obtained from a study of Löscher and Nau. Structural parameters were compared between metabolites with a double bond and metabolites with oxygen at either side chain (unpaired Student's t test). A single linear regression analysis between each structural parameter and the relative anticonvulsant potency was also performed. Results: Similar parameters were found between the cis and trans and R and S isomers. Biologic activity and most of the structural parameters were significantly different between metabolites with a double bond and metabolites with oxygen at either side chain. Activity was directly related to log P_oct (r² = 0.77) and to reactivity parameters and was inversely related to stability parameters and to molecular weight and surface. The most potent metabolites had a log P_oct value of higher than 2 units. Conclusions: Similar data were identified between cis and trans, and R and S isomers of VPA metabolites. Anticonvulsant activity was mainly related to log P_oct, probably reflecting the ability of VPA metabolites to cross the blood–brain barrier.     

Valproate-induced hyperammonemia

A patient with carbamyl phosphate synthetase deficiency had four episodes of hyperammonemia, up to 226 μM, associated with valproate (VPA) treatment. These were accompanied by vomiting, lethargy, and coma. A group of epileptic patients receiving VPA remained asymptomatic but had significantly higher mean plasma ammonium levels when compared to epileptic patients receiving other anticonvulsants: 33.6 ± 1.9 (SEM) versus 23.6 ± 1.5 μM. Thus, VPA caused symptomatic hyperammonemia in a patient with an impairment in urea synthesis and resulted in mildly elevated ammonium levels in epileptic patients. These data suggest that ammonium levels should be monitored in patients receiving VPA who exhibit signs of vomiting or lethargy.     

Characterization of dihydropyridine binding sites in the rat brain: hypertension and age-dependent modulation of [H](+)-PN 200-110 binding

The properties of [³H]dihydropyridine (DHP), nitrendipine and (+)-PN 200-110, binding to rat cerebral membranes were investigated. In normotensive Wistar-Kyoto (WKY) adult rats, the highest densities of [³H]DHP binding sites were found in the hippocampus. Frontal cerebral cortex and hypothalamus had intermediate levels and no specific binding of [³H]DHP and [¹²⁵I]iodipine could be detected in the brainstem membranes and more precisely in the nucleus tractus solitarius and in the locus coeruleus. Changes in the maximal number of DHP binding sites (B_max) were observed in spontaneously hypertensive rats (SHR) and in old Sprague-Dawley rats. In adult SHR, there was a significant increase in theB_max values of [³H](+)-PN 200-110 binding in the hippocampus when compared to the values obtained in WKY. There was no difference in theB_max values between young (3 weeks) prehypertensive SHR and age-matched WKY. In senescent (26 months) Sprague-Dawley rats, theB_max values of [³H](+)-PN 200-110 binding were significantly reduced (30%) in the frontal cerebral cortex and the hippocampus, as compared with the number of DHP binding sites found in mature Sprague-Dawley rats (15 weeks).     

Valproic acid attenuates microgliosis in injured spinal cord and purinergic P2X4 receptor expression in activated microglia

Peripheral injection with a high dose of valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, into animals with mild or moderate spinal cord injury (SCI) for 1 week can reduce spinal cord tissue loss and promote hindlimb locomotor recovery. A purinergic adenosine triphosphate (ATP) receptor subtype, P2X₄ receptor (P2X₄R), has been considered as a potential target to diminish SCI‐associated inflammatory responses. In this study, using a minipump‐based infusion system, we found that intraspinal infusion with VPA for 3 days into injured spinal cord significantly improved hindlimb locomotion of rats with severe SCI induced by a 10‐g NYU impactor dropping from the height of 50 mm onto the spinal T9/10 segment. The neuronal fibers in the injured spinal cord tissues were significantly preserved in VPA‐treated rats compared with those observed in vehicle‐treated animals. Moreover, the accumulation of microglia/macrophages and astrocytes in the injured spinal cord was attenuated in the animal group receiving VPA infusion. VPA also significantly reduced P2X₄R expression post‐SCI. Furthermore, in vitro study indicated that VPA, but not the other HDAC inhibitors, sodium butyrate and trichostatin A (TSA), caused downregulation of P2X₄R in microglia activated with lipopolysaccharide (LPS). Moreover, p38 mitogen‐activated protein kinase (MAPK)‐triggered signaling was involved in the effect of VPA on the inhibition of P2X₄R gene expression. In addition to the findings from others, our results also provide important evidence to show the inhibitory effect of VPA on P2X₄R expression in activated microglia, which may contribute to reduction of SCI‐induced gliosis and subsequently preservation of spinal cord tissues. © 2013 Wiley Periodicals, Inc.     

H2O coma

Introduction  

Water intoxication is a rare cause of coma. The leading causes of excessive hydration are endurance exercise, drug abuse, iatrogenic, cerebral salt wasting, or psychiatric conditions. Self-induced water intoxication in an otherwise healthy person is exceedingly rare.     

Serum Carnitine During Valproic Acid Therapy

This study was initiated to examine the influence of valproic acid (VPA) on serum carnitine, as well as the possible etiological role of carnitine in VPA-induced fatal hepatotoxicity. Free, total, and short-chain acylcarnitine were measured in the serum of 21 pediatric patients receiving VPA therapy, 21 healthy matched controls, and 21 patients receiving various antiepileptic drugs other than VPA. The free carnitine level was lowest in the VPA group (p less than 0.05), and the short-chain acylcarnitine/free carnitine ratio was highest in the VPA group (p less than 0.01). Patients receiving VPA polytherapy had lower total carnitine values than patients receiving VPA monotherapy (p less than 0.05). No correlation was found between serum ammonia and VPA drug levels. A 3 1/2-year-old girl developed hepatic failure under VPA therapy. Her serum carnitine values were normal. Despite the oral intake of L-carnitine this patient died. In this case, apparently VPA-induced hepatotoxicity was not associated with carnitine deficiency. The reduction of carnitine in the serum of VPA-treated patients is most probably due to alterations of fatty acid metabolism. However, neither primary carnitine deficiency nor VPA-induced secondary carnitine deficiency can be the only reason for the VPA-induced fatal hepatotoxicity.