Science review: carnitine in the treatment of valproic acid-induced toxicity - what is the evidence?

Valproate-induced worsening of seizures: clue to underlying diagnosis

The use of valproate sodium as an antiepileptic is not advised in children with an undiagnosed metabolic condition because of the increased risk of hepatotoxicity and encephalopathy. Here the authors describe a 2.5-year-old girl with a history of developmental delay, failure to thrive, and a seizure disorder whose seizures worsened after the introduction of valproate sodium. This led to a search for an underlying metabolic disorder, and after extensive investigations, a diagnosis of nonketotic hyperglycinemia was made. In this report, the authors discuss the metabolic conditions that can be worsened by valproate sodium. Valproate sodium interferes with the glycine cleavage enzyme synthesis in the mitochondria, hence increasing glycine levels. The increased glycine levels are responsible for worsening of the underlying metabolic condition and increased seizure frequency.

Characteristics of idiosyncratic drug-induced liver injury in children: results from the DILIN prospective study

BACKGROUND

The spectrum and severity of idiosyncratic drug-induced liver injury (DILI) in children are not well established.

PATIENTS AND METHODS

The DILIN (Drug-Induced Liver Injury Network) Prospective Study is a longitudinal multicenter study designed to determine the etiologies, risk factors, and outcomes of suspected DILI. Between September 2004 and September 2009, 30 children ages 2 to 18 years with suspected DILI who met eligibility criteria were enrolled and studied for at least 6 months.

RESULTS

Mean age was 14 years; 70% were girls. Antimicrobial (50%) and central nervous system agents (40%) were the most commonly implicated drug classes, with minocycline (4), isoniazid (3), azithromycin (3), atomoxetine (3), and lamotrigine (3) the leading agents. Median time from drug initiation to symptom onset was 32 days. Peak (median) liver chemistries were aspartate aminotransferase 503  U/L, alanine aminotransferase 727  U/L, alkaline phosphatase 331  U/L, and total bilirubin 3.9  mg/dL. Autoantibodies were common (64%). Liver injury pattern was hepatocellular 78%, cholestatic 13%, and mixed 9%. The DILI episode was scored: mild 32%, moderate 44%, severe 20%, and fatal (within 6 months) 4%. Causality assessment was definite 36%, very likely 36%, probable 16%, possible 8%, and unlikely 4%. Seven percent had persistent liver test abnormalities at 6-month follow-up suggesting chronic DILI. Liver biopsies from 12 children most frequently demonstrated chronic hepatitis or bile duct injury.

CONCLUSIONS

Idiosyncratic DILI in children is most commonly caused by antimicrobial or central nervous system agents and usually presents with a hepatocellular injury pattern. The majority of patients recover, but morbidity and infrequent mortality are seen.

Histone deacetylase inhibitor treatment attenuates MAP kinase pathway activation and pulmonary inflammation following hemorrhagic shock in a rodent model

BACKGROUND

Hemorrhagic shock activates cellular stress signals and can lead to systemic inflammatory response, organ injury, and death. We have previously shown that treatment with histone deacetylase inhibitors (HDACIs) significantly improves survival in lethal models (60% blood loss) of hemorrhage. The aim of the current study was to examine whether these protective effects were due to attenuation of mitogen activated protein kinase (MAPK) signaling pathways, which are known to promote inflammation and apoptosis.

METHODS

Wistar-Kyoto rats (250-300 g) were subjected to 40% blood loss and randomized to treatment with: (1) HDACI valproic acid (VPA 300 mg/kg i.v.; volume = 0.75 mL/kg), or (2) vehicle control (0.75 mL/kg of 0.9% saline). Animals were sacrificed at 1, 4, and 20 h (n = 3-4/group/timepoint), and lung samples were analyzed by Western blotting for expression of active (phosphorylated) and inactive forms of c-Jun N-terminal Kinase (JNK) and p38 MAPK. Myeloperoxidase (MPO) activity was measured in lung tissue 20 h after hemorrhage as a marker of neutrophil infiltration. Normal animals (n = 3) served as shams.

RESULTS

Hemorrhaged animals demonstrated significant increases in phosphorylated p38 at 1 h, phosphorylated JNK at 4 h, and increased MPO activity at 20 h (P < 0.05 compared with sham). VPA treatment significantly (P < 0.05) attenuated all of these changes.

CONCLUSIONS

Hemorrhagic shock activates pro-inflammatory MAPK signaling pathways and promotes pulmonary neutrophil infiltration, affects that are significantly attenuated by VPA treatment. This may represent a key mechanism through which HDACIs decrease organ damage and promote survival in hemorrhagic shock.

A case of valproate induced hyperammonemic encephalopathy

A 36-years-old man on phenytoin, levetiracetam, and sodium valproate presented with acute confusion. Routine investigations including serum valproate and phenytoin concentration were normal. His serum ammonia concentration was raised. His valproate was held and 2 days later he recovered with concordant normalisation of serum ammonia concentration. Urea acid cycle disorder was ruled out, and a diagnosis of valproate induced hyperammonemic encephalopathy (VHE) was made. Asymptomatic hyperammonemia occurs in 15-50% of valproate-treated patients, and while the true incidence of VHE is not known, it is a recognized complication of sodium valproate treatment. VHE typically presents acutely with impaired consciousness, lethargy, and vomiting. Valproate concentrations may be in the therapeutic range, and liver function tests are typically "normal." Treatment for VHE consists of ceasing valproate and providing supportive care. Some have advocated carnitine replacement.

Valproic acid-associated acute liver failure in children: case report and analysis of liver transplantation outcomes in the United States

OBJECTIVE

To determine whether valproic acid (VPA)-associated acute liver failure (ALF; VPA-ALF) explains the poor outcomes after liver transplantation (LT) in children.

STUDY DESIGN

Organ Procurement and Transplantation Network data of pediatric patients who underwent LT for VPA-ALF and ALF caused by other drugs (non-VPA-drug-induced acute liver failure [DIALF]) were analyzed. Pre- and post-transplant variables and post-LT survival were compared between VPA-ALF and non-VPA-DIALF.

RESULTS

Seventeen children were transplanted for VPA-ALF. Of the 17 children, 82% died within 1 year of LT. Pre- and post-transplant parameters of VPA versus non-VPA-DIALF were comparable with two exceptions. The median alanine aminotransferase level at transplant was remarkably lower in VPA-ALF compared with non-VPA-DIALF (45 versus 1179 IU/L, P = .004). One-year survival probability was worse in VPA-ALF than non-VPA-DIALF (20% versus 69%, P < .0001). Median post-LT survival time for VPA-ALF was 2.8 months.

CONCLUSION

Children who underwent LT for VPA-ALF had a significantly lower survival probability than children with non-VPA-DIALF. Current data suggest that VPA-ALF in children represents an "unmasking" of mitochondrial disease. VPA-ALF should be a contraindication for LT, even in the absence of a documented mitochondrial disease.

Clinical correlates of low serum carnitine levels in hospitalized psychiatric patients

OBJECTIVE

We sought to evaluate clinical correlates of low serum carnitine levels in hospitalized psychiatric patients.

METHODS

We retrospectively reviewed the charts of 40 psychiatric inpatients identified to have low serum carnitine levels.

RESULTS

Cognitive impairment was present in 38 (95%) cases, frequently accompanied by imbalance, agitation and extrapyramidal symptoms. Valproate therapy was encountered in 28 (70%) patients. The dosage of valproate negatively correlated with total and free carnitine levels (P = 0.003 and 0.0136). Polypharmacy also affected carnitine levels, indicating additional modulatory effects on carnitine metabolism. We encountered a disproportionately high prevalence of mental retardation and dementia in association with hypocarnitinemia.

CONCLUSION

We hypothesize that in the context of mental illness hypocarnitinemia may be associated with metabolic encephalopathy and cognitive impairment. As carnitine deficiency is a potentially treatable condition further studies are warranted.

Pharmacological management of seizures and status epilepticus in critically ill patients

Seizures are serious complications seen in critically ill patients and can lead to significant morbidity and mortality if the cause is not identified and treated quickly. Uncontrolled seizures can lead to status epilepticus (SE), which is considered a medical emergency. The first-line treatment of seizures is an intravenous (IV) benzodiazepine followed by anticonvulsant therapy. Refractory SE can evolve into a nonconvulsive state requiring IV anesthetics or induction of pharmacological coma. To prevent seizures and further complications in critically ill patients with acute neurological disease or injury, short-term seizure prophylaxis should be considered in certain patients.

L-Carnitine for Acute Valproic Acid Overdose: A Systematic Review of Published Cases

Objective:

To review the evidence supporting the efficacy and safety of l-carnitine in the management of acute valproic acid overdose. DATA SOURCES: MEDLINE (1950–May 2010), EMBASE (1980–May 2010), and Google Scholar (to May 2010) were searched, using the terms carnitine, valproic acid, and carnitine for valproic acid overdose. Reference citations from identified publications were reviewed.

Study Selection and Data Extraction:

Full-text publications evaluating the use of l-carnitine for management of valproic acid overdose in humans were sought. All studies, regardless of design, case series, and case reports reporting efficacy or safety endpoints were included. All languages were included. Two authors extracted primary data elements including patient demographics, presenting features, clinical management, and outcomes.

Data Synthesis:

Seven articles discussing 8 patients and 1 reporting safety data from records of 674 patients were reviewed. Reports covered both pediatric and adult patients with acute exposures to valproic acid mono- and polydrug overdose who were treated with various regimens of l-carnitine. All patients recovered clinically and no adverse effects were noted.

Conclusions:

Published evidence of the efficacy and safety of l-carnitine as an antidote for acute valproic acid overdose is limited. Based on the available evidence, it is reasonable to consider l-carnitine for patients with acute overdose of valproic acid who demonstrate decreased level of consciousness. We recommend intravenous administration of 100 mg/kg once, followed by infusions of 50 mg/kg (to a maximum of 3 g per dose) every 8 hours thereafter, continuing until ammonia levels are decreasing (if they were elevated initially) and the patient demonstrates signs of clinical improvement or until adverse events associated with l-carnitine occur.

Pharmacologic resuscitation promotes survival and attenuates hemorrhage-induced activation of extracellular signal-regulated kinase 1/2

BACKGROUND

Hemorrhage is the leading cause of preventable trauma-related deaths, and histone deacetylase inhibitors (HDACI) such as valproic acid (VPA) can improve survival following lethal hemorrhage. HDACI acetylate proteins, and acetylation regulates many cellular functions. Here we have investigated the effects of VPA treatment on extracellular signal-regulated kinase 1/2 (ERK) activation, as ERK is well known to modulate cell death, gene expression, and inflammation.

MATERIALS AND METHODS

Anesthetized Wistar-Kyoto rats were subjected to lethal (60%) blood loss, and then randomized (n = 5-6/group) to (1) VPA 300 mg/kg or (2) vehicle control. Survival was monitored for 24 h. A separate group of rats were subjected to sublethal (40%) hemorrhage and were treated with VPA or vehicle. Rats were sacrificed at 1, 4, and 20 h, and lung tissue was assessed for the degree of acetylation of histone 3, and activation (phosphorylation) of ERK. Sham animals served as normal controls.

RESULTS

Sixty percent hemorrhage resulted in severe shock. Only 17% of the vehicle-treated animals survived (most died within 1 h), whereas 80% of the VPA-treated animals survived (P < 0.05). Hemorrhage resulted in a significant increase in phosphorylated ERK (activated form) compared with sham at the 1 and 4 h time points, but not at the 20 h time point. VPA treatment significantly attenuated these changes, while increasing histone protein acetylation.

CONCLUSIONS

VPA treatment significantly improves survival following lethal hemorrhagic shock. Hemorrhage induces ERK activation, which is significantly attenuated by VPA treatment. This may represent one mechanism through which VPA promotes survival in otherwise lethal hemorrhagic shock.

Role of carnitine in disease

Carnitine is a conditionally essential nutrient that plays a vital role in energy production and fatty acid metabolism. Vegetarians possess a greater bioavailability than meat eaters. Distinct deficiencies arise either from genetic mutation of carnitine transporters or in association with other disorders such as liver or kidney disease. Carnitine deficiency occurs in aberrations of carnitine regulation in disorders such as diabetes, sepsis, cardiomyopathy, malnutrition, cirrhosis, endocrine disorders and with aging. Nutritional supplementation of L-carnitine, the biologically active form of carnitine, is ameliorative for uremic patients, and can improve nerve conduction, neuropathic pain and immune function in diabetes patients while it is life-saving for patients suffering primary carnitine deficiency. Clinical application of carnitine holds much promise in a range of neural disorders such as Alzheimer's disease, hepatic encephalopathy and other painful neuropathies. Topical application in dry eye offers osmoprotection and modulates immune and inflammatory responses. Carnitine has been recognized as a nutritional supplement in cardiovascular disease and there is increasing evidence that carnitine supplementation may be beneficial in treating obesity, improving glucose intolerance and total energy expenditure.

Potential relationships between transaminase abnormality and valproic acid clearance or serum carnitine concentrations in Japanese epileptic patients

This study tested the hypothesis that the determinants of mild liver injury are prerequisites for more severe idiosyncratic hepatotoxicity. This study verified whether the possible risk factors for rare idiosyncratic valproic acid (VPA)-induced hepatotoxicity, VPA clearance and/or serum carnitine concentrations are common to those for a mild elevation in transaminases in VPA-treated patients. VPA clearance was calculated in 172 Japanese patients with epilepsy, using a non-linear mixed-effects regression program. Carnitine concentrations were determined in a subset of 60 patients. The relationships between VPA clearance, carnitine concentration and levels of transaminases and ammonia were evaluated by Pearson's correlation coefficients. The final model of VPA apparent clearance (CL/F) was as follows: CL/F (L h−1) = 0.012 × (BW/40)0.34 × dose0.55 × 0.90gender × 1.32PHT × 1.11CBZ × 1.12PB, where BW = total body weight (kg); gender = 1 if female, 0 if male; PHT/CBZ/PB = 1 if phenytoin, carbamazepine, or phenobarbital, respectively, is coadministrated, otherwise 0. Either a higher VPA clearance or acyl/free carnitine ratio and a lower total and/or free carnitine concentration, but not VPA concentration, were associated with the mild elevation in transaminases or ammonia. These results support the initial hypothesis, while also helping to clarify the mechanism of severe idiosyncratic hepatotoxicity with VPA.

Lipid oxidation and peroxidation in CNS health and disease: from molecular mechanisms to therapeutic opportunities

Reactive oxygen species (ROS) are produced at low levels in mammalian cells by various metabolic processes, such as oxidative phosphorylation by the mitochondrial respiratory chain, NAD(P)H oxidases, and arachidonic acid oxidative metabolism. To maintain physiological redox balance, cells have endogenous antioxidant defenses regulated at the transcriptional level by Nrf2/ARE. Oxidative stress results when ROS production exceeds the cell's ability to detoxify ROS. Overproduction of ROS damages cellular components, including lipids, leading to decline in physiological function and cell death. Reaction of ROS with lipids produces oxidized phospholipids, which give rise to 4-hydroxynonenal, 4-oxo-2-nonenal, and acrolein. The brain is susceptible to oxidative damage due to its high lipid content and oxygen consumption. Neurodegenerative diseases (AD, ALS, bipolar disorder, epilepsy, Friedreich's ataxia, HD, MS, NBIA, NPC, PD, peroxisomal disorders, schizophrenia, Wallerian degeneration, Zellweger syndrome) and CNS traumas (stroke, TBI, SCI) are problems of vast clinical importance. Free iron can react with H(2)O(2) via the Fenton reaction, a primary cause of lipid peroxidation, and may be of particular importance for these CNS injuries and disorders. Cholesterol is an important regulator of lipid organization and the precursor for neurosteroid biosynthesis. Atherosclerosis, the major risk factor for ischemic stroke, involves accumulation of oxidized LDL in the arteries, leading to foam cell formation and plaque development. This review will discuss the role of lipid oxidation/peroxidation in various CNS injuries/disorders.

Drugs and pharmaceuticals: management of intoxication and antidotes

The treatment of patients poisoned with drugs and pharmaceuticals can be quite challenging. Diverse exposure circumstances, varied clinical presentations, unique patient-specific factors, and inconsistent diagnostic and therapeutic infrastructure support, coupled with relatively few definitive antidotes, may complicate evaluation and management. The historical approach to poisoned patients (patient arousal, toxin elimination, and toxin identification) has given way to rigorous attention to the fundamental aspects of basic life support--airway management, oxygenation and ventilation, circulatory competence, thermoregulation, and substrate availability. Selected patients may benefit from methods to alter toxin pharmacokinetics to minimize systemic, target organ, or tissue compartment exposure (either by decreasing absorption or increasing elimination). These may include syrup of ipecac, orogastric lavage, activated single- or multi-dose charcoal, whole bowel irrigation, endoscopy and surgery, urinary alkalinization, saline diuresis, or extracorporeal methods (hemodialysis, charcoal hemoperfusion, continuous venovenous hemofiltration, and exchange transfusion). Pharmaceutical adjuncts and antidotes may be useful in toxicant-induced hyperthermias. In the context of analgesic, anti-inflammatory, anticholinergic, anticonvulsant, antihyperglycemic, antimicrobial, antineoplastic, cardiovascular, opioid, or sedative-hypnotic agents overdose, N-acetylcysteine, physostigmine, L-carnitine, dextrose, octreotide, pyridoxine, dexrazoxane, leucovorin, glucarpidase, atropine, calcium, digoxin-specific antibody fragments, glucagon, high-dose insulin euglycemia therapy, lipid emulsion, magnesium, sodium bicarbonate, naloxone, and flumazenil are specifically reviewed. In summary, patients generally benefit from aggressive support of vital functions, careful history and physical examination, specific laboratory analyses, a thoughtful consideration of the risks and benefits of decontamination and enhanced elimination, and the use of specific antidotes where warranted. Data supporting antidotes effectiveness vary considerably. Clinicians are encouraged to utilize consultation with regional poison centers or those with toxicology training to assist with diagnosis, management, and administration of antidotes, particularly in unfamiliar cases.

Clinical outcomes and low-dose levocarnitine supplementation in psychiatric inpatients with documented hypocarnitinemia: a retrospective chart review

BACKGROUND

Metabolic encephalopathy is one of the crucial manifestations of carnitine deficiency. In psychiatric patients, low serum carnitine levels may result from chronic valproate therapy. Despite the widespread use of valproate in psychiatry, neither carnitine deficiency nor supplementation has been studied in a psychiatric population.

OBJECTIVE

To describe clinical outcomes in hospitalized psychiatric patients with documented hypocarnitinemia who were receiving oral levocarnitine supplementation.

METHOD

Retrospective chart review.

RESULTS

In 38 patients with hypocarnitinemia, a low-dose oral levocarnitine supplementation, in association with comprehensive psychiatric therapy, did not result in any adverse psychiatric or medical outcomes, and was associated with overall improved behavioral, cognitive, and motor functioning. Initially all patients had some degree of cognitive impairment, but after correction of carnitine serum levels, scores on the Mini-Mental State Examination (MMSE) improved in most of the patients (mean improvement 5.5 points, P <0.0001), and normalized in 11 cases. This allowed a correction of the diagnosis in 8 of 14 patients who had initially been diagnosed with dementia. African-American patients achieved significantly lower serum carnitine levels and MMSE scores than Caucasian patients with comparable therapy.

CONCLUSION

We hypothesize that correction of carnitine depletion, either by levocarnitine supplementation or by valproate dose reduction, may enhance recovery from hypocarnitinemia-associated encephalopathy in psychiatric patients. Our findings also suggest that ethnic traits may affect carnitine bioavailability as well as cognitive outcomes in this clinical context. Further studies of carnitine metabolism and supplementation in psychiatric patients are warranted.

The Use of Carnitine Rather than Renal Replacement Therapy for Sodium Valproate Poisoning

Valproate toxicity can be complicated by the development of hyperammonaemia, which can cause cerebral oedema and encephalopathy. We report the successful management of a case of valproate overdose using carnitine and review the metabolic pathways responsible for its therapeutic effects.

Stupor and fast activity on electroencephalography in a child treated with valproate

The case of a 4-year-old girl with valproate-induced stupor and electroencephalographic pattern of increased fast activity is reported. Stupor and fast activity have been related to the effects on gamma-aminobutyric acid type A (GABA(A)) receptors mediated by endozepines or by exogenous drugs such as benzodiazepines or barbiturates. The action of valproate in GABA metabolism and in GABA neuronal networks could produce a similar result through a hyperrecruitment of GABA-mediated postsynaptic transmission.

Surviving blood loss without blood transfusion in a swine poly-trauma model

BACKGROUND

We have demonstrated previously that valproic acid (VPA), a histone deacetylase inhibitor, can improve survival in lethal models of hemorrhagic shock. This study investigated whether VPA treatment would improve survival in a clinically relevant large animal model of poly-trauma/hemorrhagic shock, and whether the protective effects are executed through the Akt survival pathway.

METHODS

Yorkshire swine were subjected to a poly-trauma protocol including: (1) Pre-hospital phase- Femur fracture, 60% hemorrhage, 30 min of shock (mean arterial pressure [MAP]: 25-30 mmHg), and infusion of 154mM NaCl (3 x shed blood); (2) Early hospital phase A Grade V liver injury (simulating rupture of a previously contained hematoma) followed by liver packing; (3) Treatment/monitoring phase randomization to 3 treatment groups (n = 6-8/group): no treatment (control), fresh whole blood (FWB), and intravenous VPA (400 mg/kg, given during the pre-hospital phase). Animals were monitored for 4 h, with survival being the primary endpoint. Liver tissue was subjected to Western blot analysis.

RESULTS

FWB (n = 6) and VPA treatments (n = 7) significantly increased survival (100% and 86%, respectively) compared to control group (n = 8) (25%). The protocol produced significant anemia (Hb<6 g/dL) and lactic acidosis (lactate 3-5 mmol/L). Acidosis improved after blood transfusion and worsened in the other two groups. VPA treatment increased phospho-Akt (activated), phospho-GSK-3beta (Glycogen synthase kinase 3beta), beta-catenin and Bcl-2 (B-cell leukemia/lymphoma 2) protein levels compared to control group (P = .01, .01, .03, and .02, respectively). There was no significant difference in the level of these proteins between the control and FWB groups.

CONCLUSION

Treatment with VPA without blood transfusion improves early survival in a highly lethal poly-trauma and hemorrhagic shock model. The survival advantage is due not to improvement in resuscitation but to better tolerance of shock by the cells, in part due to the preservation of the Akt survival pathway.

Chiral toxicology: it's the same thing...only different

Chiral substances possess a unique architecture such that, despite sharing identical molecular formulas, atom-to-atom linkages, and bonding distances, they cannot be superimposed. Thus, in the environment of living systems, where specific structure-activity relationships may be required for effect (e.g., enzymes, receptors, transporters, and DNA), the physiochemical and biochemical properties of racemic mixtures and individual stereoisomers can differ significantly. In drug development, enantiomeric selection to maximize clinical effects or mitigate drug toxicity has yielded both success and failure. Further complicating genetic polymorphisms in drug disposition, stereoselective metabolism of chiral compounds can additionally influence pharmacokinetics, pharmacodynamics, and toxicity. Optically pure pharmaceuticals may undergo racemization in vivo, negating single enantiomer benefits or inducing unexpected effects. Appropriate chiral antidotes must be selected for therapeutic benefit and to minimize adverse events. Enantiomers may possess different carcinogenicity and teratogenicity. Environmental toxicology provides several examples in which compound bioaccumulation, persistence, and toxicity show chiral dependence. In forensic toxicology, chiral analysis has been applied to illicit drug preparations and biological specimens, with the potential to assist in determination of cause of death and aid in the correct interpretation of substance abuse and "doping" screens. Adrenergic agonists and antagonist, nonsteroidal anti-inflammatory agents, SSRIs, opioids, warfarin, valproate, thalidomide, retinoic acid, N-acetylcysteine, carnitine, penicillamine, leucovorin, glucarpidase, pesticides, polychlorinated biphenyls, phenylethylamines, and additional compounds will be discussed to illustrate important concepts in "chiral toxicology."

Valproate-induced hyperammonemic encephalopathy treated by hemodialysis

Valproate-induced hyperammonemic encephalopathy is an unusual but serious complication that may occur in people with normal liver-associated enzyme levels, despite normal therapeutic doses and serum levels of valproate. Here, we describe an adolescent girl who had absence seizure and complained about progressive dizziness and general malaise several days after restarting valproate. Then, she presented vomiting and decreased consciousness three weeks after valproate use. Notably, her serum ammonia level was five times the upper limit of normal (184 micrommol/L), with normal liver-associated enzyme and supra-therapeutic valproate level. EEG showed continuous generalized slowing. The tandem mass analysis revealed carnitine deficiency. Consciousness improved after emergent hemodialysis. Ammonia level and EEG also returned to normal. Possible mechanisms, risk factors and the treatments of valproate-induced hyperammonemic encephalopathy are described. Physicians should consider this possibility when consciousness disturbance occurs in patients treated with valproate.

Serum and muscle carnitine levels in epileptic children receiving sodium valproate

The purpose of this study was to determine whether children with epilepsy undergoing valproate therapy and who are otherwise healthy have lower levels of serum and muscle carnitine. A total of 50 patients with epilepsy, 3 to 14 years of age, who were treated solely with valproate and free of abnormal neurologic findings or nutritional problems were selected. The control group consisted of 30 healthy children. The total carnitine levels in serum were 28.1 +/- 10.3 and 55.6 +/-7.3 microg/mL, and the free carnitine levels in serum were 16.5 +/-10.2 and 44.6 +/-7.3 microg/mL, the total carnitine levels in muscle were 12.1 +/- 1.8 and 45.3 +/- 5.9 micromol/g noncollagen protein and the free carnitine levels in muscle were 5.6 +/- 1.6 and 39.3 +/- 6.0 micromol/g noncollagen protein in the valproic acid-treated and control groups, respectively (P < .05). In conclusion, valproate monotherapy depletes both muscle and serum carnitine levels in otherwise healthy epileptic children.

Acute liver impairment after sodium valproate overdose

Liver impairment is a recognised adverse effect of long-term sodium valproate treatment, but there are few reports concerning its occurrence after acute overdose. This report describes a 36-year-old woman who deliberately ingested 32 g of sodium valproate (Epilim). Serum valproate concentration was 4370 μmol/l (630 mg/l) at 4.3 h post-ingestion (therapeutic reference range: 300-600 μmol/l), and the elimination half-life was 14.1 h. Liver biochemistry tests were initially normal but gradually became impaired, and highest alanine aminotransferase (761 U/l) occurred 2.3 days after ingestion. Supportive measures alone were sufficient to allow recovery of liver function. This case indicates that sodium valproate overdose may cause acute hepatocellular injury, even in the absence of pre-existing liver disease.

Hepatotoxicity associated with antiepileptic drugs

BACKGROUND

Drug-induced liver injury associated with antiepileptic drugs (AED) is well recognized. The frequency of the most common AED is rare but the consequences can be very serious leading to death or liver transplantation due to acute liver failure induced by these drugs.

CLINICAL FEATURES

Hypersensitivity features are found in more than 70% of patients with phenytoin-induced liver injury, whereas this is only observed in 30% of carbamazepine-associated hepatotoxicity and very rarely with valproate (VPA)-induced liver injury.

PATHOPHYSIOLOGY

The underlying mechanisms behind hepatotoxicity induced by AED are not clear. Reactive metabolites from AED can, in some cases, lead to direct cytotoxicity and liver cell necrosis, whereas in other cases this may lead to neoantigen formation inducing immunoallergic mechanisms.

TREATMENT

No specific therapy is of proved value in severe hepatotoxicity due to AED. However, N-acetylcystein is an appropriate treatment in patients with clinically significant liver injury due to phenytoin and carbamazepine. In patients with VPA-associated liver injury, carnitine that is an important co-factor in the mitochondrial beta-oxidation of fatty acids is the recommended treatment. Early referral of patients with severe liver reactions and coagulopathy to liver transplant centers before encephalopathy can be the difference between liver transplantation and death.

Valproate-induced hyperammonemic encephalopathy

Valproate-induced hyperammonemic encephalopathy is an unusual but serious complication that can occur in people with normal liver-associated enzyme levels, and despite normal therapeutic doses and serum levels of valproate. Here, we describe an adolescent girl suffering from absence seizures, who complained of progressive dizziness and general malaise several days after restarting valproate. She developed vomiting and decreased consciousness after 3 weeks of valproate use. She had a serum ammonia level five times higher than the upper normal limit, normal liver-associated enzymes, and a supra-therapeutic valproate level. Electroencephalography (EEG) showed continuous generalized slowing. Tandem mass spectrometry analysis revealed carnitine deficiency. Her consciousness improved after emergent hemodialysis. Her ammonia level and EEG also became normal. Possible mechanisms, risk factors and treatments of valproate-induced hyperammonemic encephalopathy are described. Physicians should consider this possibility when consciousness disturbance occurs in patients treated with valproate.

Oral valproic acid for epilepsy--long-term experience in therapy and side effects

Valproic acid (VPA) is considered to be a drug of first choice and one of the most frequently-prescribed antiepileptic drugs worldwide for the therapy of generalized and focal epilepsies, including special epileptic. It is a broad-spectrum antiepileptic drug and is usually well tolerated. Rarely, serious complications may occur in some patients, including hemorrhagic pancreatitis, coagulopathies, bone marrow suppression, VPA-induced hepatotoxicity and encephalopathy, but there is still a lack of knowledge about the incidence and occurrence of these special side effects. Additionally, the consequences for VPA therapy and indication are more or less unclear. By literature review and own data this review addresses some of the challenges of VPA therapy and its side effects, which are not unique to epilepsy in childhood.

Valproic acid metabolism and its effects on mitochondrial fatty acid oxidation: a review

Valproic acid (VPA; 2-n-propylpentanoic acid) is widely used as a major drug in the treatment of epilepsy and in the control of several types of seizures. Being a simple fatty acid, VPA is a substrate for the fatty acid beta-oxidation (FAO) pathway, which takes place primarily in mitochondria. The toxicity of valproate has long been considered to be due primarily to its interference with mitochondrial beta-oxidation. The metabolism of the drug, its effects on enzymes of FAO and their cofactors such as CoA and/or carnitine will be reviewed. The cumulative consequences of VPA therapy in inborn errors of metabolism (IEMs) and the importance of recognizing an underlying IEM in cases of VPA-induced steatosis and acute liver toxicity are two different concepts that will be emphasized.

Valproate-induced hyperammonaemic encephalopathy: review of 14 cases in the psychiatric setting

OBJECTIVES

To review signs and symptoms of valproate-induced hyperammonaemic encephalopathy without hepatotoxicity in the psychiatric setting, explore its mechanisms, and give recommendations for prevention and treatment.

METHODS

Medline search with keywords valproate, ammonia, hyperammonaemia, encephalopathy, and then cross-references to articles obtained through this search. Only cases with indication of valproate for psychiatric condition were included.

RESULTS

Fourteen cases published in the psychiatric setting are reviewed. Valproate-induced hyperammonaemic encephalopathy is a rare adverse event, occurring almost equally in men and women, with a large age range, and reported in two patients with mental retardation. Symptoms appeared either a few days after initiation of valproate therapy, or after several months or years. The main symptoms were fluctuations in consciousness and disorientation. Clinical severity was not related to blood ammonia levels. All patients recovered after valproate-induced hyperammonaemic encephalopathy diagnosis and treatment, usually involving discontinuation of valproate.

CONCLUSIONS

Valproate-induced hyperammonaemic encephalopathy is rare and usually reversible in patients without urea cycle disorders when valproate is discontinued. Therapy with carnitine is recommended. Special caution should be used in patients with mental retardation. Psychiatrists should suspect valproate-induced hyperammonaemic encephalopathy when consciousness deteriorates.

Changes in l-carnitine content of fish and meat during domestic cooking

Human adults store around 20g of l-carnitine. In the human body, l-carnitine is not metabolized but excreted through the kidney. Lost l-carnitine has to be replenished either by a biosynthetic mechanism or by the consumption of foods containing l-carnitine. Today, there is no "official" recommended daily allowance for l-carnitine but the daily need for l-carnitine intake has been estimated in the wide range of 2-12μmol/day/kg body weight for an adult human. In this study we evaluated the effect of freezing and of different cooking methods on the l-carnitine content of red meat and fish. l-carnitine was abundantly present in all beef products analyzed. The amounts in the various cuts were similar and our data showed that freezing or cooking did not modify l-carnitine content. Salmon contained about 12 times less l-carnitine than beef but except in smoked salmon, cooking or freezing did not alter l-carnitine content. This study confirms the important role that meet products play for providing adequate amount of l-carnitine to the human body.

Sodium valproate exerts neuroprotective effects in vivo through CREB-binding protein-dependent mechanisms but does not improve survival in an amyotrophic lateral sclerosis mouse model

Amyotrophic lateral sclerosis (ALS) is characterized by motoneuron (MN) degeneration, generalized weakness, and muscle atrophy. The premature death of MNs is thought to be a determinant in the onset of this disease. In a transgenic mouse model of ALS expressing the G86R mutant superoxide dismutase 1 (mSOD1), we demonstrated previously that CREB (cAMP response element-binding protein)-binding protein (CBP) and histone acetylation levels were specifically decreased in nuclei of degenerating MNs. We show here that oxidative stress and mSOD1 overexpression can both impinge on CBP levels by transcriptional repression, in an MN-derived cell line. Histone deacetylase inhibitor (HDACi) treatment was able to reset proper acetylation levels and displayed an efficient neuroprotective capacity against oxidative stress in vitro. Interestingly, HDACi also upregulated CBP transcriptional expression in MNs. Moreover, when injected to G86R mice in vivo, the HDACi sodium valproate (VPA) maintained normal acetylation levels in the spinal cord, efficiently restored CBP levels in MNs, and significantly prevented MN death in these animals. However, despite neuroprotection, mean survival of treated animals was not significantly improved (<5%), and they died presenting the classical ALS symptoms. VPA was not able to prevent disruption of neuromuscular junctions, although it slightly delayed the onset of motor decline and retarded muscular atrophy to some extent. Together, these data show that neuroprotection can improve disease onset, but clearly provide evidence that one can uncouple MN survival from whole-animal survival and point to the neuromuscular junction perturbation as a primary event of ALS onset.

Is valproate encephalopathy under-recognised in older people? A case series

BACKGROUND

Valproate (VPA) is an antiepileptic drug with a broad spectrum of efficacy. Although usually well-tolerated, it may have side-effects of which encephalopathy is one of the most serious.

OBJECTIVE

To describe the clinical characteristics of valproate encephalopathy (VE) in five older patients with remote symptomatic seizures treated with rapid VPA loading.

DESIGN

Case series.

SETTING

Teaching hospital

PATIENTS

Five patients (71-89 years old) with underlying cerebrovascular disease or dementia and symptomatic seizures.

RESULTS

VE was characterised by decline in conscious level and (in some cases) increase in seizure frequency. Three of the five patients had elevated ammonia levels. EEG showed generalised slow activity, in some cases accompanied by additional epileptic discharges. The condition was reversible in four patients after VPA discontinuation. One patient died.

CONCLUSIONS

Older people may be at particular risk of VE because of co-morbid pathology, age-related metabolic changes and co-medication.

Carnitine as an antidote for acute valproate toxicity in children

PURPOSE OF REVIEW

Valproic acid is a widely used anticonvulsant that has recently been approved for stabilization of manic episodes in patients with bipolar disorder. As the use of valproic acid increases, the number of both accidental and intentional exposures increases. This is paralleled by more reports of valproic-acid-induced toxicity. The purpose of this article is to review the pathophysiology and toxicology of valproic acid and determine whether the literature supports the use of carnitine as a treatment for acute valproic-acid-induced toxicity.

RECENT FINDINGS

Recent literature documents no cases of allergic reactions or serious side effects associated with the administration of carnitine when given patients with acute ingestions of valproic acid. Other findings suggest that carnitine increases the survival rate of patients who develop valproic-acid-induced hepatotoxicity. Early intervention with intravenous rather than enteral L-carnitine was associated with the greatest hepatic survival. Isolated pediatric case reports show that carnitine administration may reverse toxic metabolic pathways but may not hasten clinical improvement.

SUMMARY

Based on this recent literature, it seems reasonable to use carnitine for documented severe valproic acid toxicity, particularly in cases where patients present with coma, rising ammonia level, or valproic acid levels greater than 450 mg/l.

Valproic acid induced encephalopathy – 19 new cases in Germany from 1994 to 2003 – A side effect associated to VPA-therapy not only in young children

Valproic acid (VPA) is a broad-spectrum antiepileptic drug and is usually well-tolerated. Rare serious complications may occur in some patients, including haemorrhagic pancreatitis, bone marrow suppression, VPA-induced hepatotoxicity and VPA-induced encephalopathy. The typical signs of VPA-induced encephalopathy are impaired consciousness, sometimes marked EEG background slowing, increased seizure frequency, with or without hyperammonemia. There is still no proof of causative effect of VPA in patients with encephalopathy, but only of an association with an assumed causal relation. We report 19 patients with VPA-associated encephalopathy in Germany from the years 1994 to 2003, none of whom had been published previously.