Selective blockade of N-type calcium channels by levetiracetam

Subcutaneous Levetiracetam Administration in Latino Patients on Home Care

Background: Levetiracetam has a favorable pharmacology profile to be used subcutaneously. However, its subcutaneous use is still considered off-label as this is beyond its license. The evidence base for its safety, tolerability, and efficacy is limited to observational studies. Objectives: To report the safety and efficacy of subcutaneous levetiracetam in Latino patients on home care. Design: Observational retrospective case series study. Subjects: Consecutive sample of Latino adults with life-limiting illnesses. Methods: A case series framework with 4 domains (selection, ascertainment, causality, and reporting) to ensure reporting quality was used. Additionally, 8 relevant outcomes established in a previous comprehensive review, were collected and reported. Adverse reactions were documented using the Common Terminology Criteria for Adverse Events. Results: Fifteen Latino patients with oncological and non-oncological diagnoses received subcutaneous levetiracetam for a mean of 21 days on home care. Levetiracetam was most frequently initiated subcutaneously due to loss of the oral route. The average dosage of subcutaneous levetiracetam was 1200 mg. Only 1 patient required a dose adjustment, and only 2 patients experienced a total of 5 seizures during the therapy trial. No adverse reactions were reported. Conclusions: Subcutaneous levetiracetam appears to be effective and safe. This case series of Latino patients in home care expands the evidence of its use in the home care setting. The preliminary data reported by now on multiple case series warrants robust trials.

Effect of Levetiracetam on Oxidant-Antioxidant Activity during Long-Term Temporal Lobe Epilepsy in Rats

Epilepsy is a disorder characterized by a predisposition to generate seizures. Levetiracetam (LEV) is an antiseizure drug that has demonstrated oxidant-antioxidant effects during the early stages of epilepsy in several animal models. However, the effect of LEV on oxidant-antioxidant activity during long-term epilepsy has not been studied. Therefore, the objective of the present study was to determine the effects of LEV on the concentrations of five antioxidant enzymes and on the levels of four oxidant stress markers in the hippocampus of rats with temporal lobe epilepsy at 5.7 months after status epilepticus (SE). The results revealed that superoxide dismutase (SOD) activity was significantly greater in the epileptic group (EPI) than in the control (CTRL), CTRL + LEV and EPI + LEV groups. No significant differences were found among the groups' oxidant markers. However, the ratios of SOD/hydrogen peroxide (H2O2), SOD/glutathione peroxidase (GPx) and SOD/GPx + catalase (CAT) were greater in the EPI group than in the CTRL and EPI + LEV groups. Additionally, there was a positive correlation between SOD activity and GPx activity in the EPI + LEV group. LEV-mediated modulation of the antioxidant system appears to be time dependent; at 5.7 months after SE, the role of LEV may be as a stabilizer of the redox state.

Behavioral and neurotransmitter changes on antiepileptic drugs treatment in the zebrafish pentylenetetrazol-induced seizure model

Epilepsy, a recurrent neurological disorder involving abnormal neurotransmitter kinetics in the brain, has emerged as a global health concern. The mechanism of epileptic seizures is thought to involve a relative imbalance between excitatory and inhibitory neurotransmitters. Despite the recent advances in clinical and basic research on the pathogenesis of epilepsy, the complex relationship between the neurotransmitter changes and behavior with and without antiepileptic drugs (AEDs) during seizures remains unclear. To investigate the effects of AEDs such as levetiracetam (LEV), carbamazepine (CBZ), and fenfluramine (FFR) on key neurotransmitters in the pentylenetetrazol (PTZ)-induced seizures in adult zebrafish, we examined the changes in glutamic acid, gamma-aminobutyric acid (GABA), serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), choline, acetylcholine, norepinephrine, dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), and adenosine. In this study, we observed that 5-HT and DA levels in the brain increased immediately after PTZ-induced seizures. Behavioral tests clearly showed that all of these AEDs suppressed the PTZ-induced seizures. Upon treatment of PTZ-induced seizures with these AEDs, CBZ decreased the glutamic acid and FFR increased the GABA levels; however, no neurotransmitter changes were observed in the brain after LEV administration. Thus, we demonstrated a series of neurotransmitter changes linked to behavioral changes during PTZ-induced epileptic seizures when LEV, CBZ, or FFR were administered. These findings will lead to a more detailed understanding of the pathogenesis of epilepsy associated with behavioral and neurotransmitter changes under AED treatment.

Phenotypic Screening of Prospective Analgesics Among FDA-Approved Compounds using an iPSC-Based Model of Acute and Chronic Inflammatory Nociception

Classical target-based drug screening is low-throughput, largely subjective, and costly. Phenotypic screening based on in vitro models is increasingly being used to identify candidate compounds that modulate complex cell/tissue functions. Chronic inflammatory nociception, and subsequent chronic pain conditions, affect peripheral sensory neuron activity (e.g., firing of action potentials) through myriad pathways, and remain unaddressed in regard to effective, non-addictive management/treatment options. Here, a chronic inflammatory nociception model is demonstrated based on induced pluripotent stem cell (iPSC) sensory neurons and glia, co-cultured on microelectrode arrays (MEAs). iPSC sensory co-cultures exhibit coordinated spontaneous extracellular action potential (EAP) firing, reaching a stable baseline after ≈27 days in vitro (DIV). Spontaneous and evoked EAP metrics are significantly modulated by 24-h incubation with tumor necrosis factor-alpha (TNF-α), representing an inflammatory phenotype. Compared with positive controls (lidocaine), this model is identified as an "excellent" stand-alone assay based on a modified Z' assay quality metric. This model is then used to screen 15 cherry-picked, off-label, Food and Drug Administration (FDA)-approved compounds; 10 of 15 are identified as "hits". Both hits and "misses" are discussed in turn. In total, this data suggests that iPSC sensory co-cultures on MEAs may represent a moderate-to-high-throughput assay for drug discovery targeting inflammatory nociception.

Differential inflammation responses determine the variable phenotypes of epilepsy induced by GABRG2 mutations

OBJECTIVE

To explore the mechanism involved in variable phenotypes of epilepsy models induced by γ-aminobutyric acid type A γ2 subunit (GABRG2) mutations.

METHODS

The zebrafish carrying wild-type (WT) GABRG2, mutant GABRG2(P282S), GABRG2(F343L) and GABRG2(I107T) were established by Tol2kit transgenesis system and Gateway method. Behavioral analysis of different transgenic zebrafish was performed with the DanioVision Video-Track framework and the brain activity was analyzed by field potential recording with MD3000 Bio-signal Acquisition and Processing System. The transcriptome analysis was applied to detect the underlying mechanisms of variable phenotypes caused by different GABRG2 mutations.

RESULTS

The established Tg(hGABRG2P282S ) zebrafish showed hyperactivity and spontaneous seizures, which were more sensitive to chemical and physical epileptic stimulations. Traditional antiepileptic drugs, such as Clonazepam (CBZ) and valproic acid (VPA), could ameliorate the hyperactivity in Tg(hGABRG2P282S ) zebrafish. The metabolic pathway was significantly changed in the brain transcriptome of Tg(hGABRG2P282S ) zebrafish. In addition, the behavioral activity, production of pro-inflammatory factors, and activation of the IL-2 receptor signal pathway varied among the three mutant zebrafish lines.

CONCLUSION

We successfully established transgenic zebrafish epileptic models expressing human mutant GABRG2(P282S), in which CBZ and VPA showed antiepileptic effects. Differential inflammatory responses, especially the SOCS/JAK/STAT signaling pathway, might be related to the phenotypes of genetic epilepsy induced by GABRG2 mutations. Further study will expand the pathological mechanisms of genetic epilepsies and provide a theoretical basis for searching for effective drug treatment.

Changes in the Dentate Gyrus Gene Expression Profile Induced by Levetiracetam Treatment in Rats with Mesial Temporal Lobe Epilepsy

Temporal lobe epilepsy (TLE) is one of the most common forms of focal epilepsy. Levetiracetam (LEV) is an antiepileptic drug whose mechanism of action at the genetic level has not been fully described. Therefore, the aim of the present work was to evaluate the relevant gene expression changes in the dentate gyrus (DG) of LEV-treated rats with pilocarpine-induced TLE. Whole-transcriptome microarrays were used to obtain the differential genetic profiles of control (CTRL), epileptic (EPI), and EPI rats treated for one week with LEV (EPI + LEV). Quantitative RT-qPCR was used to evaluate the RNA levels of the genes of interest. According to the results of the EPI vs. CTRL analysis, 685 genes were differentially expressed, 355 of which were underexpressed and 330 of which were overexpressed. According to the analysis of the EPI + LEV vs. EPI groups, 675 genes were differentially expressed, 477 of which were downregulated and 198 of which were upregulated. A total of 94 genes whose expression was altered by epilepsy and modified by LEV were identified. The RT-qPCR confirmed that LEV treatment reversed the increased expression of Hgf mRNA and decreased the expression of the Efcab1, Adam8, Slc24a1, and Serpinb1a genes in the DG. These results indicate that LEV could be involved in nonclassical mechanisms involved in Ca2+ homeostasis and the regulation of the mTOR pathway through Efcab1, Hgf, SLC24a1, Adam8, and Serpinb1a, contributing to reduced hyperexcitability in TLE patients.

GWAS meta-analysis of over 29,000 people with epilepsy identifies 26 risk loci and subtype-specific genetic architecture

Epilepsy is a highly heritable disorder affecting over 50 million people worldwide, of which about one-third are resistant to current treatments. Here we report a multi-ancestry genome-wide association study including 29,944 cases, stratified into three broad categories and seven subtypes of epilepsy, and 52,538 controls. We identify 26 genome-wide significant loci, 19 of which are specific to genetic generalized epilepsy (GGE). We implicate 29 likely causal genes underlying these 26 loci. SNP-based heritability analyses show that common variants explain between 39.6% and 90% of genetic risk for GGE and its subtypes. Subtype analysis revealed markedly different genetic architectures between focal and generalized epilepsies. Gene-set analyses of GGE signals implicate synaptic processes in both excitatory and inhibitory neurons in the brain. Prioritized candidate genes overlap with monogenic epilepsy genes and with targets of current antiseizure medications. Finally, we leverage our results to identify alternate drugs with predicted efficacy if repurposed for epilepsy treatment.

Effect of levetiracetam therapy on electrocardiographic parameters

AIM

The purpose of this study was to compare the electrocardiographic parameters before and at the sixth month of treatment of patients diagnosed with epilepsy and who were started on levetiracetam therapy.

METHODS

The files of 30 patients diagnosed with epilepsy and on levetiracetam therapy were examined in this study. Clinical findings, electroencephalography (EEG), cranial magnetic resonance imaging (MRI) and electrocardiography (ECG) data before and at the sixth month of treatment were recorded.

RESULTS

The patients' mean age was 10.93 ± 3.74 (4-17) years; 16 (53.33%) patients were boys. In total, 13 (43.3%) were found to experience focal seizures, and 17 (56.7%) generalized epilepsy-type seizures. Comparison of the ECG parameters (PR interval, QTc, QT interval, and QRS duration) revealed a shortening in the PR interval and QTc values at the sixth month of treatment, although the changes were not statistically significant. No significant differences in terms of gender and epilepsy types were observed between the ECG parameters before treatment and at the sixth month (p > 0.05).

CONCLUSION

In this study, levetiracetam was found to have no effect on ECG parameters.

N-Type Ca Channel in Epileptic Syndromes and Epilepsy: A Systematic Review of Its Genetic Variants

N-type voltage-gated calcium channel controls the release of neurotransmitters from neurons. The association of other voltage-gated calcium channels with epilepsy is well-known. The association of N-type voltage-gated calcium channels and pain has also been established. However, the relationship between this type of calcium channel and epilepsy has not been specifically reviewed. Therefore, the present review systematically summarizes existing publications regarding the genetic associations between N-type voltage-dependent calcium channel and epilepsy.

Efficacy and safety of levetiracetam versus valproate in patients with established status epilepticus: A systematic review and meta-analysis

Objective

Status epilepticus (SE) is a common neurological emergency that is defined as a prolonged seizure or a series of seizures which often leads to irreversible damage. Levetiracetam (LEV) and valproate (VPA) are second-line anti-seizure drugs that are frequently used in patients with established SE (ESE). This meta-analysis compared the efficacy and safety of LEV and VPA for the treatment of ESE.

Method

MEDLINE, EMBASE, Central Register of Controlled Trials (CENTRAL), and clinicaltrials.gov were searched by two authors, which identified six randomized controlled trials (RCTs) that compared LEV and VPA for ESE.

Results

The six RCTs included 1213 patients (LEV group, n = 593; VPA group, n = 620). Integrated patient data information display LEV was not superior to VPA in terms of clinical seizure termination (63.55% vs. 64.08%, respectively; relative risk [RR] = 1.03, 95% confidence interval [CI] = 0.94-1.11, p = 0.55), with no significant differences between LEV and VPA in terms of good functional outcome at discharge (Glasgow Outcome Scale [GOS] = 4 or 5), intensive care unit (ICU) admission, adverse events, and mortality. There was no statistically significant difference between the two drugs in different age groups. Previous multicenter studies have demonstrated that VPA was slightly more effective than LEV, whereas single-center studies showed the opposite results. In addition, LEV and VPA had similar rates of clinical seizure termination, ICU admission, and adverse events between the age subgroups (ages <18 and >18 years).

Conclusions

Levetiracetam (LEV) was not superior to valproate (VPA) in terms of efficacy or safety outcomes. In addition, children (<18 years) and adults (>18 years) might have similar responses to LEV and VPA. Additional RCTs are required to verify our results.

Levetiracetam Attenuates Adolescent Stress-induced Behavioral and Electrophysiological Changes Associated With Schizophrenia in Adult Rats

BACKGROUND AND HYPOTHESIS

Stress during adolescence is a major risk factor for schizophrenia. We have found previously in rats that adolescent stress caused, in adulthood, behavioral changes and enhanced ventral tegmental area (VTA) dopamine system activity, which were associated with dysregulation of the excitatory-inhibitory (E/I) balance in the ventral hippocampus (vHip). Levetiracetam, an anticonvulsant drug, regulates the release of neurotransmitters, including glutamate, via SV2A inhibition. It also modulates parvalbumin interneuron activity via Kv3.1 channels. Therefore, levetiracetam could ameliorate deficits in the E/I balance. We tested whether levetiracetam attenuate the adolescent stress-induced behavioral changes, vHip hyperactivity, and enhanced VTA dopamine system activity in adult rats.

STUDY DESIGN

Male Sprague-Dawley rats were subjected to a combination of daily footshock (postnatal day [PD] 31-40), and three 1 h-restraint stress sessions (at PD31, 32, and 40). In adulthood (PD62), animals were tested for anxiety responses (elevated plus-maze and light-dark box), social interaction, and cognitive function (novel object recognition test). The activity of vHip pyramidal neurons and VTA dopamine neurons was also recorded.

STUDY RESULTS

Adolescent stress produced anxiety-like responses and impaired sociability and cognitive function. Levetiracetam (10 mg/kg) reversed these changes. Levetiracetam also reversed the increased VTA dopamine neuron population activity and the enhanced firing rate of vHip pyramidal neurons induced by adolescent stress.

CONCLUSIONS

These findings suggest that levetiracetam attenuates the adverse outcomes associated with schizophrenia caused by stress during adolescence.

Antiseizure Medications for the Prophylaxis of Migraine during the Anti- CGRP Drugs Era

Migraine and epilepsy are fundamentally distinct disorders that can frequently coexist in the same patient. These two conditions significantly differ in diagnosis and therapy but share some widely- used preventive treatments. Antiseizure medications (ASMs) are the mainstay of therapy for epilepsy, and about thirty different ASMs are available to date. ASMs are widely prescribed for other neurological and non-neurological conditions, including migraine. However, only topiramate and valproic acid/valproate currently have an indication for migraine prophylaxis supported by high-quality evidence. Although without specifically approved indications and with a low level of evidence or recommendation, several other ASMs are used for migraine prophylaxis. Understanding ASM antimigraine mechanisms, including their ability to affect the pro-migraine calcitonin gene-related peptide (CGRP) signaling pathway and other pathways, may be instrumental in identifying the specific targets of their antimigraine efficacy and may increase awareness of the neurobiological differences between epilepsy and migraine. Several new ASMs are under clinical testing or have been approved for epilepsy in recent years, providing novel potential drugs for migraine prevention to enrich the treatment armamentarium and drugs that inhibit the CGRP pathway.

The differential effect of levetiracetam on memory and anxiety in rats

OBJECTIVE

One of the newest antiseizure medication is levetiracetam (LEV). It might be effective in various indications, not only related to convulsions. Central nervous system disorders are common during anticonvulsant therapy. The aim of this study was to assess the effect of LEV on various types of memory and anxiety in rats.

METHODS

Adult male Wistar rats (n = 58) were given LV p.o. as a single (100 mg/kg or 500 mg/kg) or repeated doses (300 mg/kg). The effect of the drug on memory was assessed in the Morris water maze (MWM) (spatial memory), the passive avoidance (PA) (emotional memory) and the novel object recognition (NOR) (recognition memory). The anxiety was evaluated in the elevated plus maze (EPM).

RESULTS

LEV administered as repeated doses disturbed the long-term recognition memory in NOR and locomotor activity in EPM. A single dose affected emotional memory in PA. LEV did not alter spatial memory in MWM.

CONCLUSIONS

LEV may cause memory and locomotor disturbances, but some of these adverse effects seem to be temporary and limited to the effect of acute dose.

Antiseizure medication in early nervous system development. Ion channels and synaptic proteins as principal targets

The main strategy for the treatment of epilepsy is the use of pharmacological agents known as antiseizure medication (ASM). These drugs control the seizure onset and improves the life expectancy and quality of life of patients. Several ASMs are contraindicated during pregnancy, due to a potential teratogen risk. For this reason, the pharmacological treatments of the pregnant Women with Epilepsy (WWE) need comprehensive analyses to reduce fetal risk during the first trimester of pregnancy. The mechanisms by which ASM are teratogens are still under study and scientists in the field, propose different hypotheses. One of them, which will be addressed in this review, corresponds to the potential alteration of ASM on ion channels and proteins involved in relevant signaling and cellular responses (i.e., migration, differentiation) during embryonic development. The actual information related to the action of ASM and its possible targets it is poorly understood. In this review, we will focus on describing the eventual presence of some ion channels and synaptic proteins of the neurotransmitter signaling pathways present during early neural development, which could potentially interacting as targets of ASM. This information leads to elucidate whether these drugs would have the ability to affect critical signaling during periods of neural development that in turn could explain the fetal malformations observed by the use of ASM during pregnancy.

Levetiracetam or Phenobarbitone as a First-Line Anticonvulsant in Asphyxiated Term Newborns? An Open-Label, Single-Center, Randomized, Controlled, Pragmatic Trial

BACKGROUND AND OBJECTIVE

Neonatal seizures are one of the most challenging problems for experts across the globe. Although there is no consensus on the "ideal" treatment of neonatal seizures, phenobarbitone has been the drug of choice for decades. Unfortunately, although extensively studied in adults and children, levetiracetam lacks rigorous evaluation in the neonatal population, despite its frequent use as an off-label drug. The objective of this open-label, randomized, active-control, single-center, pragmatic trial was to compare the effectiveness of levetiracetam with phenobarbitone for term asphyxiated infants as a first-line drug.

METHODS

The participants included in this study were inborn term asphyxiated infants with seizures in the first 48 hours of life. Infants satisfying the inclusion criteria were randomized to receive levetiracetam (20 mg/kg) or phenobarbitone (20 mg/kg). Clinical seizure control was noted. Infants who failed to respond to the primary drug were given the other group drug.

RESULTS

Of 103 eligible infants, 82 were randomly assigned (44 levetiracetam group, 38 phenobarbitone group). Clinical seizure control with the primary drug and maintenance of the same for 24 hours was observed in 29 infants (65.9%) in the levetiracetam group and 13 infants (34.2%) in the phenobarbitone group (P < .05, relative risk 0.52, 95% confidence interval 0.32-0.84). Of the infants in the phenobarbitone group who did not respond to the primary drug, 57.8% were controlled after adding levetiracetam.

CONCLUSION

Levetiracetam can be used with effectiveness as a first- and second-line drug in asphyxiated term infants. A more extensive study on pharmacokinetics and optimal regimen is required.

Differential effects of levetiracetam on hippocampal CA1 synaptic plasticity and molecular changes in the dentate gyrus in epileptic rats

Temporal lobe epilepsy (TLE) is the most common form of focal epilepsies. Pharmacological treatment with anti-seizure drugs (ASDs) remains the mainstay in epilepsy management. Levetiracetam (LEV) is a second-generation ASD with a novel SV2A protein target and is indicated for treating focal epilepsies. While there is considerable literature in acute models, its effect in chronic epilepsy is less clear. Particularly, its effects on neuronal excitability, synaptic plasticity, adult hippocampal neurogenesis, and histological changes in chronic epilepsy have not been evaluated thus far, which formed the basis of the present study. Six weeks post-lithium-pilocarpine-induced status epilepticus (SE), epileptic rats were injected with levetiracetam (54mg/kg b.w. i.p.) once daily for two weeks. Following LEV treatment, Schaffer collateral - CA1 (CA3-CA1) synaptic plasticity and structural changes in hippocampal subregions CA3 and CA1 were evaluated. The number of doublecortin (DCX⁺) and reelin (RLN⁺) positive neurons was estimated. Further, mossy fiber sprouting was evaluated in DG by Timm staining, and splash test was performed to assess the anxiety-like behavior. Chronic epilepsy resulted in decreased basal synaptic transmission and increased paired-pulse facilitation without affecting post-tetanic potentiation and long-term potentiation. Moreover, chronic epilepsy decreased hippocampal subfields volume, adult hippocampal neurogenesis, and increased reelin expression and mossy fiber sprouting with increased anxiety-like behavior. LEV treatment restored basal synaptic transmission and paired-pulse facilitation ratio in CA3-CA1 synapses. LEV also restored the CA1 subfield volume in chronic epilepsy. LEV did not affect epilepsy-induced abnormal adult hippocampal neurogenesis, ectopic migration of newborn granule cells, mossy fiber sprouting in DG, and anxiety-like behavior. Our results indicate that in addition to reducing seizures, LEV has favorable effects on synaptic transmission and structural plasticity in chronic epilepsy. These findings add new dimensions to the use of LEV in chronic epilepsy and paves way for further research into its effects on cognition and affective behavior.

Levetiracetam Mechanisms of Action: From Molecules to Systems

Epilepsy is a chronic disease that affects millions of people worldwide. Antiepileptic drugs (AEDs) are used to control seizures. Even though parts of their mechanisms of action are known, there are still components that need to be studied. Therefore, the search for novel drugs, new molecular targets, and a better understanding of the mechanisms of action of existing drugs is still crucial. Levetiracetam (LEV) is an AED that has been shown to be effective in seizure control and is well-tolerable, with a novel mechanism of action through an interaction with the synaptic vesicle protein 2A (SV2A). Moreover, LEV has other molecular targets that involve calcium homeostasis, the GABAergic system, and AMPA receptors among others, that might be integrated into a single mechanism of action that could explain the antiepileptogenic, anti-inflammatory, neuroprotective, and antioxidant properties of LEV. This puts it as a possible multitarget drug with clinical applications other than for epilepsy. According to the above, the objective of this work was to carry out a comprehensive and integrative review of LEV in relation to its clinical uses, structural properties, therapeutical targets, and different molecular, genetic, and systemic action mechanisms in order to consider LEV as a candidate for drug repurposing.

Pain in Multiple Sclerosis: Understanding Pathophysiology, Diagnosis, and Management Through Clinical Vignettes

Neuropathic pain and other pain syndromes occur in the vast majority of patients with multiple sclerosis at some time during their disease course. Pain can become chronic and paroxysmal. In this review, we will utilize clinical vignettes to describe various pain syndromes associated with multiple sclerosis and their pathophysiology. These syndromes vary from central neuropathic pain or Lhermitte's phenomenon associated with central nervous system lesions to trigeminal neuralgia and optic neuritis pain associated with nerve lesions. Muscular pain can also arise due to spasticity. In addition, we will discuss strategies utilized to help patients manage these symptoms.

Antiseizure medication discovery: Recent and future paradigm shifts

Despite the ever-increasing number of available options for the treatment of epilepsies and the remarkable advances on the understanding of their pathophysiology, the proportion of refractory patients has remained approximately unmodified during the last 100 years. How efficient are we translating positive outcomes from basic research to clinical trials and/or the clinical scenario? It is possible that fresh thinking and exploration of new paradigms is required to arrive at truly novel therapeutic solutions, as seemingly proven by recently approved first-in-class antiseizure medications and drug candidates undergoing late clinical trials. Here, the author discusses some approximations in line with the network pharmacology philosophy, which may result in highly innovative (and, hopefully, safer and/or more efficacious) medications for the control of seizures, as embodied with some recent examples in the field, namely tailored multi-target agents and low-affinity ligands.

Gordonia hydrophobica Nitrile Hydratase for Amide Preparation from Nitriles

The active pharmaceutical ingredient levetiracetam has anticonvulsant properties and is used to treat epilepsies. Herein, we describe the enantioselective preparation of the levetiracetam precursor 2-(pyrrolidine-1-yl)butanamide by enzymatic dynamic kinetic resolution with a nitrile hydratase enzyme. A rare representative of the family of iron-dependent nitrile hydratases from Gordonia hydrophobica (GhNHase) was evaluated for its potential to form 2-(pyrrolidine-1-yl)butanamide in enantioenriched form from the three small, simple molecules, namely, propanal, pyrrolidine and cyanide. The yield and the enantiomeric excess (ee) of the product are determined most significantly by the substrate concentrations, the reaction pH and the biocatalyst amount. GhNHase is also active for the hydration of other nitriles, in particular for the formation of N-heterocyclic amides such as nicotinamide, and may therefore be a tool for the preparation of various APIs.

The Effect of Epilepsy and Antiepileptic Drugs on Cortical Motor Excitability in Patients With Temporal Lobe Epilepsy

OBJECTIVES

Transcranial magnetic stimulation (TMS) has been used to assess cortical disinhibition/excitation with epilepsy and determine the degree of patients' response to antiepileptic drugs (AEDs). However, the results of studies are variable and conflicting. We assessed cortical motor excitability in adults with temporal lobe epilepsy (TLE).

METHODS

The TMS parameters used for assessment were: resting (RMT) and active (AMT) motor thresholds, cortical silent period (CSP), and central motor conduction time (CMCT).

RESULTS AND CONCLUSIONS

This study included 40 adults (males, 22; females, 18) with TLE with impaired awareness or to bilateral tonic clonic seizures (mean age, 32.50 ± 3.38 years; duration of illness, 6.15 ± 2.02 years) and on treatment with AEDs (valproate, 15; carbamazepine, 15; levetiracetam, 10]. The majority (62.5%) were seizure-free for ≥1 year on AEDs before TMS testing. All had normal brain magnetic resonance imaging except two, who had mesial temporal sclerosis. Comparing the entire patients with controls, patients had significantly bihemispheric higher RMT and AMT particularly over the epileptic hemisphere and shorter CSP and CMCT in the epileptic hemisphere. Shorter CSP and CMCT were observed in patients on valproate or carbamazepine and those who were uncontrolled on medications but not with levetiracetam. Significant correlations were identified between RMT and AMT (P = 0.01) and between CSP and CMCT (P = 0.001). We conclude that chronic TLE had increased cortical disinhibition in the epileptic hemisphere which can spread outside the epileptogenic zone despite the apparent control on AEDs. The TMS studies using CSP and CMCT may help future prediction of pharmacoresistance and, therefore, the need of combined AEDs with multiple mechanisms of action.

Treating Status Epilepticus: Phenytoin Versus Levetiracetam

For decades, phenytoin has been the drug of choice for the treatment of epilepsy but also the second-line treatment for status epilepticus (SE). However, newer antiepileptic drugs (AEDs) have emerged as safer alternatives for the suppression of seizures. Consequently, phenytoin has recently fallen under scrutiny in the research world, prompting many studies to compare its efficacy to these other drugs, most notably levetiracetam. Levetiracetam is a second-generation AED, which is gaining wide clinical use as the second-line agent in treating SE patients. This review focuses on several clinical studies that have directly compared the effectiveness of phenytoin and levetiracetam in suppressing SE seizure activity. Additionally, this review highlights several advantages of using levetiracetam over phenytoin in this clinical context.

Glutathione and Related Molecules in Parkinsonism

Glutathione (GSH) is the most abundant intrinsic antioxidant in the central nervous system, and its substrate cysteine readily becomes the oxidized dimeric cystine. Since neurons lack a cystine transport system, neuronal GSH synthesis depends on cystine uptake via the cystine/glutamate exchange transporter (xCT), GSH synthesis, and release in/from surrounding astrocytes. Transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), a detoxifying master transcription factor, is expressed mainly in astrocytes and activates the gene expression of various phase II drug-metabolizing enzymes or antioxidants including GSH-related molecules and metallothionein by binding to the antioxidant response element (ARE) of these genes. Accumulating evidence has shown the involvement of dysfunction of antioxidative molecules including GSH and its related molecules in the pathogenesis of Parkinson’s disease (PD) or parkinsonian models. Furthermore, we found several agents targeting GSH synthesis in the astrocytes that protect nigrostriatal dopaminergic neuronal loss in PD models. In this article, the neuroprotective effects of supplementation and enhancement of GSH and its related molecules in PD pathology are reviewed, along with introducing new experimental findings, especially targeting of the xCT-GSH synthetic system and Nrf2–ARE pathway in astrocytes.

Effects of new antiseizure drugs on seizure activity and anxiety-like behavior in adult zebrafish

Several studies with larvae and adult zebrafish have shown that old and new antiseizure drugs (ASDs) produce discrepant results in seizure tests, locomotor activity or anxiety models. In this study, the pentylenetetrazole seizure test (PTZ) was performed to assess the effectiveness of four new ASDs: lamotrigine (LTG), topiramate (TPM), felbamate (FBM), and levetiracetam (LEV) in the subsequent stages of seizures in adult fish. All ASDs were administered intraperitoneally (i.p.). The time of maximal anticonvulsant effect and the dose-response relationship of the drugs were assessed. The effects of studied ASDs on the locomotor activity and the anxiety-like behavior in the color preference test were also investigated. Furthermore, drug concentrations in zebrafish homogenates were determined. LTG, TPM, and LEV significantly increased the seizure latency at three subsequent stages of seizures (SI-SIII), while FBM was effective only at SI. Locomotor activity decreased after TPM treatment. TPM and FBM exhibited a strong anxiolytic-like effect in the color preference test. LEV at the highest dose tested had a weak anxiolytic-like effect. The HPLC analysis showed average concentrations of the studied ASDs in the fish body during their maximum anticonvulsant activity. The present study shows that FBM cannot inhibit all subsequent PTZ seizure stages in the adult fish. Except for LTG, the studied drugs affected the anxiety-like behavior of treated animals. Furthermore, only TPM significantly changed locomotion parameters. Our findings support the need to accurately characterize the efficacy of new ASDs at different stages of the PTZ-induced seizures in adult zebrafish.

Initial levetiracetam versus valproate monotherapy in antiseizure medicine (ASM)-naïve pediatric patients with idiopathic generalized epilepsy with tonic-clonic seizures

INTRODUCTION

Levetiracetam (LEV) is a second-generation antiseizure medicine (ASM) with broad-spectrum efficacy and tolerability. Few studies have compared the efficacy of valproate (VPA) and LEV as monotherapy in the pediatric population. Herein, we compare the efficacy, tolerability and safety of LEV monotherapy with those of VPA monotherapy in ASM-naïve pediatric patients with idiopathic generalized epilepsy with tonic-clonic (GTC) seizures.

METHODS

We retrospectively analyzed the clinical and electroencephalographic (EEG) data of these ASM-naïve pediatric patients who were treated with either oral VPA or oral LEV as monotherapy for over 2 years at our center.

RESULTS

This study included 60 patients with a seizure onset age between 2 months and 12 years. The patients on VPA (29 patients) and LEV monotherapy (31 patients) showed similar favorable 6-month treatment outcomes (complete seizure control in 79.31% vs 80.64%, p = 0.468052). Age at epilepsy onset, epilepsy syndrome, EEG features and ASM dose were not significant predictors of the 6-month treatment outcomes in either group. Lower seizure frequency at presentation was a predictor of favorable 6-month treatment outcomes in the LEV group but not in the VPA group. VPA and LEV treatment showed similar favorable 6-month treatment outcomes in the febrile seizures plus and patients with unidentified epilepsy syndrome subgroups. None of the patients discontinued VPA or LEV due to treatment-associated adverse effects.

DISCUSSION

Our study showed that compared to VPA monotherapy, LEV monotherapy in ASM-naïve infants and children with idiopathic generalized epilepsy with GTC seizures has a similarly favorable efficacy and tolerability, independent of age, EEG features and epilepsy syndrome.

Population Pharmacokinetics of Levetiracetam: A Systematic Review

BACKGROUND

Levetiracetam has been widely used as a treatment option for different types of epilepsy in both adults and children. Because of its large between-subject variability, several population pharmacokinetic studies have been performed to identify its pharmacokinetic covariates, and thus facilitate individualised therapy.

OBJECTIVE

The aim of this review was to provide a synopsis for population pharmacokinetic studies of levetiracetam and explore the identified influencing covariates.

METHODS

We systematically searched the PubMed and Embase databases from inception to 30 June 2020. The information on study designs, target population, model characteristics, and identified covariates was summarised. Moreover, the pharmacokinetic profiles were compared among neonates, children, and adults.

RESULTS

Fourteen studies were included, among which two involved neonates, four involved children, two involved both children and adults, and six involved adults only. The median value of apparent clearance for children (0.074 L/h/kg [range 0.038-0.079]) was higher than that for adults (0.054 L/h/kg [range 0.039-0.061]). Body weight was found to significantly influence the apparent clearance and volume of distribution, whereas renal function influenced the clearance. Likewise, coadministration with enzyme-inducing antiepileptic drugs (such as carbamazepine and phenytoin) increased the drug clearance by 9-22%, whereas coadministration with valproate acid decreased it by 18.8%.

CONCLUSION

Levetiracetam dose regimen is dependent on the body size and renal function of patients. Further studies are needed to evaluate levetiracetam pharmacokinetics in neonates and pregnant women.

Challenges of Delirium Management in Patients with Traumatic Brain Injury: From Pathophysiology to Clinical Practice

Traumatic brain injury (TBI) can initiate a very complex disease of the central nervous system (CNS), starting with the primary pathology of the inciting trauma and subsequent inflammatory and CNS tissue response. Delirium has long been regarded as an almost inevitable consequence of moderate to severe TBI, but more recently has been recognized as an organ dysfunction syndrome with potentially mitigating interventions. The diagnosis of delirium is independently associated with prolonged hospitalization, increased mortality and worse cognitive outcome across critically ill populations. Investigation of the unique problems and management challenges of TBI patients is needed to reduce the burden of delirium in this population. In this narrative review, possible etiologic mechanisms behind post-traumatic delirium are discussed, including primary injury to structures mediating arousal and attention and secondary injury due to progressive inflammatory destruction of the brain parenchyma. Other potential etiologic contributors include dysregulation of neurotransmission due to intravenous sedatives, seizures, organ failure, sleep cycle disruption or other delirium risk factors. Delirium screening can be accomplished in TBI patients and the presence of delirium portends worse outcomes. There is evidence that multi-component care bundles including an analgesia-prioritized sedation algorithm, regular spontaneous awakening and breathing trials, protocolized delirium assessment, early mobility and family engagement can reduce the burden of ICU delirium. The aim of this review is to summarize the approach to delirium in TBI patients with an emphasis on pathogenesis and management. Emerging CNS-active drug therapies that show promise in preclinical studies are highlighted.

Evaluation of the effectiveness of valproic acid for treating cyanotic breath holding spells: A Pilot prospective study

BACKGROUND

Cyanotic breath-holding spells (CBHS) are self-limited conditions among younger children. Frequent spells cause parents' fear and anxiety. Seizures, brain damage and sudden death have been rarely reported with BHS. Some reported spells' frequency reduction with iron or piracetam. We evaluated the effectiveness of valproic acid (VPA) to treat CBHS and predictors of improvement.

METHODS

Participants were 90 children with CBHS (≥4/week) (age: 1.6±0.4yrs). They were treated with VPA (5 mg/kg/d). Follow-ups occurred after 3-≥6 months. Autonomic nervous system functions were evaluated.

RESULTS

The majority (74.4%) had daily spells and 19% had ≥2 spells/d. Crying or anger provoked spells. Postural hypotension was found in 46.7%. They had normal electroencephalography and QT, QTc interval or QTd or QTcd and heart rate. Compared to controls, postural fall in systolic (>20mmHg) and diastolic (>10mmHg) blood pressures and mean arterial pressure (>10mmHg) were observed in 46.7%, 74.4% and 72.2% and miosis observed with 0.125% pilocarpine in 28.9% (P=0.001). Spells' frequency reduction (P=0.001) occurred within 3 months with VPA. The independent prdictors for spell' frequency reduction were reduction of anger and crying [OR=4.52(95%CI=2.35-6.04), P =0.01].

CONCLUSION

VPA therapy reduces CBHS' frequency. Mood improvement is a suggestive effective mechanism.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.gov identifier is NCT04482764.

Pharmacokinetic, pharmacodynamic, and neurochemical investigations of lamotrigine-pentylenetetrazole kindled mice to ascertain it as a reliable model for clinical drug-resistant epilepsy

BACKGROUND

Pentylenetetrazole kindling has long been used for the screening of investigational antiseizure drugs. The presence of lamotrigine, at a very low dose, does not hamper kindling in mice; rather it modifies this epileptogenesis process into drug-resistant epilepsy. The lamotrigine-pentylenetetrazole kindled mice show resistance to lamotrigine, phenytoin, and carbamazepine. It may also be possible that other licensed antiseizure drugs, like the mentioned drugs, remain ineffective in this model; therefore, this was the subject of this study.

METHODS

Swiss albino mice were kindled with pentylenetetrazole for 35 days in the presence of either methylcellulose vehicle or lamotrigine (subtherapeutic dose, ie, 5 mg/kg). Vehicle vs lamotrigine-kindled mice were compared in terms of (a) resistance/response toward nine antiseizure drugs applied as monotherapies and two drug combinations; (b) lamotrigine bioavailability in blood and brain; (c) blood-brain barrier integrity; and (d) amino acids and monoamines in the cerebral cortex and hippocampus.

RESULTS

Lamotrigine vs vehicle-kindled mice are similar (or not significantly different P > .05 from each other) in terms of (a) response toward drug combinations; (b) lamotrigine bioavailability; and (c) blood-brain barrier integrity except for, significantly (P < .05) reduced taurine and increased glutamate in the cerebral cortex and hippocampus. Aside from these, lamotrigine-kindled mice show significant (P < .05) resistant to lamotrigine (15 mg/kg), levetiracetam (40 mg/kg); carbamazepine (40 mg/kg), zonisamide (100 mg/kg), gabapentin (224 mg/kg), pregabalin (30 mg/kg), phenytoin (35 mg/kg), and topiramate (300 mg/kg).

CONCLUSION

Lamotrigine-pentylenetetrazole kindling takes longer to develop (~5 weeks) in comparison to lamotrigine-amygdale (~4 weeks) and lamotrigine-corneal (~2 weeks) kindling models. However, drug screening through this model may yield superior drugs with novel antiseizure mechanisms.

Pathophysiology of Hyperkalemia Presenting as Brugada Pattern on Electrocardiogram (ECG)

BACKGROUND Brugada phenocopies (BrP) are clinical and electrocardiographic (ECG) entities elicited by reversible medical conditions speculated to have pathogenesis rooted in ion current imbalances or conduction delays within the myocardial wall. During an inciting pathologic condition, it produces ECG patterns identical to those of congenitally-acquired Brugada syndrome and subsequently returns to normal ECG patterns upon resolution of the medical condition. This case report describes a 26-year-old man presenting to the Emergency Department (ED) for suspected heroin overdose with a rare ECG consistent with BrP secondary to acute hyperkalemia. CASE REPORT A 26-year-old man with a history of substance abuse and a seizure disorder presented to the ED for acute encephalopathy secondary to a heroin overdose complicated by severe rhabdomyolysis and acute renal failure. Laboratory investigations showed acute hyperkalemia (potassium of 7.2 mmol/L) in addition to an elevated creatine kinase, severe transaminitis, and elevated creatinine. His ECG on admission revealed Brugada-like changes in leads V1-V2, with subsequent resolution upon bicarbonate administration and normalization of potassium. After initial stabilization, the patient was admitted to the Intensive Care Unit (ICU). His rhabdomyolysis and acute kidney injury improved after copious rehydration. He was found to have community-acquired pneumonia, with a negative infectious disease workup, that improved with antibiotics. Upon resolution of his hypoxemic respiratory failure and improvement in mentation, he was discharged from the hospital. CONCLUSIONS Our case report adds to the growing literature on BrP and highlights the importance of recognizing its characteristic ECG pattern as a unique presentation of a common electrolyte derangement.

Levetiracetam add-on for drug-resistant focal epilepsy

BACKGROUND

Drug resistance is common in focal epilepsy. In this update, we summarised the current evidence regarding add-on levetiracetam in treating drug-resistant focal epilepsy. The original review was published in 2001 and last updated in 2012.

OBJECTIVES

To evaluate the effectiveness of levetiracetam when used as an add-on treatment for people with drug-resistant focal epilepsy.

SEARCH METHODS

We searched the Cochrane Register of Studies (CRS Web, which includes the Cochrane Epilepsy Group Specialized Register and CENTRAL), MEDLINE Ovid, ClinicalTrials.gov, and the WHO International Clinical Trials Registry Platform (ICTRP) to November 2018. We contacted the manufacturers of levetiracetam and researchers in the field to seek any ongoing or unpublished trials.

SELECTION CRITERIA

Randomised, placebo-controlled trials of add-on levetiracetam treatment in people with drug-resistant focal epilepsy.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, assessed trials for bias, extracted data, and evaluated the overall certainty of the evidence. Outcomes investigated included 50% or greater reduction in focal seizure frequency (response), treatment withdrawal, adverse effects (including a specific analysis of changes in behaviour), cognitive effects, and quality of life (QoL). Primary analysis was intention-to-treat. We performed meta-analysis for all outcomes using a Mantel-Haenszel approach and calculated risk ratios (RR), with 95% confidence intervals (CI) for all estimates apart from adverse effects (99% CIs). We assessed heterogeneity using a Chi² test and the I² statistic.

MAIN RESULTS

This update included 14 trials (2455 participants), predominantly possessing low risks of bias. Participants were adults in 12 trials (2159 participants) and children in the remaining two (296 participants). The doses of levetiracetam tested were 500 mg/day to 4000 mg/day in adults, and 60 mg/kg/day in children. Treatment ranged from 12 to 24 weeks. When individual doses were examined, levetiracetam at either 500 mg/day or 4000 mg/day did not perform better than placebo for the 50% or greater reduction in seizure frequency outcome (500 mg: RR 1.60, 95% CI 0.71 to 3.62; P = 0.26; 4000 mg: RR 1.64, 95% CI 0.59 to 4.57; P = 0.34). Levetiracetam was significantly better than placebo at all other individual doses (1000 mg to 3000 mg). RR was significantly in favour of levetiracetam compared to placebo when results were pooled across all doses (RR 2.37, 95% CI 2.02 to 2.78; 14 studies, 2455 participants; moderate-certainty evidence). Dose-response analysis demonstrated that the odds of achieving response (50% or greater reduction in seizure frequency) were increased by nearly 40% (odds ratio (OR) 1.39, 95% CI 1.23 to 1.58) for each 1000 mg increase in dose of levetiracetam. There were important levels of heterogeneity across multiple comparisons. Participants were not significantly more likely to experience treatment withdrawal with levetiracetam than with placebo (pooled RR 1.11, 95% CI 0.89 to 1.40; 13 studies, 2428 participants; high-certainty evidence). Somnolence was the most common adverse effect, affecting 13% of participants, and it was significantly associated with levetiracetam compared to placebo (pooled RR 1.62, 99% CI 1.19 to 2.20; 13 studies, 2423 participants; moderate-certainty evidence). Changes in behaviour were negligible in adults (1% affected; RR 1.79, 99% CI 0.59 to 5.41), but significant in children (23% affected; RR 1.90, 99% CI 1.16 to 3.11). Levetiracetam had a positive effect on some aspects of cognition and QoL in adults and worsened certain aspects of child behaviour.

AUTHORS' CONCLUSIONS

Overall, this review update finds that in both adults and children with drug-resistant focal epilepsy, levetiracetam added on to usual care is more effective than placebo at reducing seizure frequency, it is unlikely to be stopped by patients, and it has minimal adverse effects outside of potential worsening behaviour in children. These findings are unchanged from the previous review update in 2012. This review update contributes two key additional findings: 1. a 500 mg daily dose of levetiracetam is no more effective than placebo at reducing seizures; and 2. the odds of response (50% reduction in seizure frequency) are increased by nearly 40% for each 1000 mg increase in dose of levetiracetam. It seems reasonable to continue the use of levetiracetam in both adults and children with drug-resistant focal epilepsy.

Resting state signal latency assesses the propagation of intrinsic activations and estimates anti-epileptic effect of levetiracetam in Rolandic epilepsy

PURPOSE

We assessed the potential of resting-state fMRI lag analysis (RSLA) in detecting epileptic activation and in estimating anti-epileptic effects of Levetiracetam (LEV) in Rolandic epilepsy.

METHODS

Forty-three children with Rolandic epilepsy underwent simultaneous EEG-fMRI. They were grouped into LEV vs drug-naïve groups according to their medication, and into patients who showed or did not show central-temporal spike (CTS) discharges during scans. We calculated the lag structure of rs-fMRI for all patients and assessed interactions with drug (LEV vs. drug-naïve) and CTS status (CTS vs. no-CTS). We furthermore assessed correlations between lag values and number of CTS and medication conditions.

RESULTS

RSLA analysis indicated earlier intrinsic activations in bilateral Rolandic areas when CTS occurred. More frequent epileptic discharges were correlated with earlier intrinsic activations (r=-0.46, p = 0.03 left Rolandic). Patients with LEV therapy, on the other hand, displayed delayed intrinsic activity in Rolandic areas compared to drug-naïve patients CONCLUSION: Our RSLA analysis indicated an association between centro-temporal spikes and earlier hemodynamic activations in epileptogenic regions in Rolandic epilepsy, which were counteracted by LEV treatment. As it allows for the mapping of propagation features of intrinsic activity and drug-effects, our findings suggest potential of lag based analyses in detecting focus localization and estimating treatment effects.

Cortical excitability in epilepsy and the impact of antiepileptic drugs: transcranial magnetic stimulation applications

INTRODUCTION

Epileptic conditions are characterized by impaired cortical excitation/inhibition balance and interneuronal disinhibition. Transcranial magnetic stimulation (TMS) is a neurophysiological method that assesses brain excitation/inhibition.

AREA COVERED

This review was written after a detailed search in PubMed, EMBASE, ISI web of science, SciELO, Scopus, and Cochrane Controlled Trials databases from 1990 to 2020. It summarizes TMS applications for diagnostic and therapeutic purposes in epilepsy. TMS studies help to distinguish different epilepsy conditions and explore the antiepileptic drugs' (AEDs') effects on neuronal microcircuits and plasticity mechanisms. Repetitive TMS studies showed that low-frequency rTMS (0.33-1 Hz) can reduce seizures' frequency in refractory epilepsy or pause ongoing seizures; however, there is no current approval for its use in such patients as adjunctive treatment to AEDs.

EXPERT OPINION

There are variable and conflicting TMS results which reflect the distinct pathogenic mechanisms of each epilepsy condition, the dynamic epileptogenic process over the long disease course resulting in the development of recurrent spontaneous seizures and/or progression of epilepsy after it is established, and the differential effect of AEDs on cortical excitability. Future epilepsy research should focus on combined TMS/functional connectivity studies that explore the complex cortical excitability circuits and networks using different TMS parameters and techniques.

Brivaracetam attenuates pain behaviors in a murine model of neuropathic pain

Background

The antiseizure racetams may provide novel molecular insights into neuropathic pain due to their unique mechanism involving synaptic vesicle glycoprotein 2A. Anti-allodynic effects of levetiracetam have been shown in animal models of neuropathic pain. Here, we studied the effect of brivaracetam, which binds to synaptic vesicle glycoprotein 2A with 20-fold greater affinity, and has fewer off-target effects.

Methods

Mice underwent unilateral sciatic nerve cuffing and were evaluated for mechanical sensitivity using von Frey filaments. Pain behaviors were assessed with prophylactic treatment using levetiracetam (100 or 10 mg/kg) or brivaracetam (10 or 1 mg/kg) beginning after surgery and continuing for 21 days, or with therapeutic treatment using brivaracetam (10 or 1 mg/kg) beginning on day 14, after allodynia was established, and continuing for 28 or 63 days. Spinal cord tissues from the prophylaxis experiment with10 mg/kg brivaracetam were examined for neuroinflammation (Iba1 and tumor necrosis factor), T-lymphocyte (CD3) infiltration, and synaptic vesicle glycoprotein 2A expression.

Results

When used prophylactically, levetiracetam, 100 mg/kg, and brivaracetam, 10 mg/kg, prevented the development of allodynia, with lower doses of each being less effective. When used therapeutically, brivaracetam extinguished allodynia, requiring 10 days with 10 mg/kg, and six weeks with 1 mg/kg. Brivaracetam was associated with reduced neuroinflammation and reduced T-lymphocyte infiltration in the dorsal horn. After sciatic nerve cuffing, synaptic vesicle glycoprotein 2A expression was identified in neurons, activated astrocytes, microglia/macrophages, and T lymphocytes in the dorsal horn.

Conclusion

Synaptic vesicle glycoprotein 2A may represent a novel target for neuropathic pain. Brivaracetam may warrant study in humans with neuropathic pain due to peripheral nerve injury.

The safety of medications used to treat peripheral neuropathic pain, part 1 (antidepressants and antiepileptics): review of double-blind, placebo-controlled, randomized clinical trials

INTRODUCTION

Peripheral neuropathic pain is a highly disabling condition for patients and a challenge for neurologists and pain physicians. Although many drugs have been assessed in scientific studies, few have demonstrated a clear clinical efficacy against neuropathic pain. Moreover, the paucity of data regarding their safety raised the question on the benefit-risk ratio when used in patients experiencing peripheral neuropathies.

AREAS COVERED

The authors conducted a review of double-blind, placebo-controlled, randomized clinical trials to assess the safety of medications used to treat neuropathic pain. This first review was focused on antidepressant and antiepileptic medications. The aim was to provide an overview of the treatment-emergent adverse events (≥10%) and the serious adverse effects described in clinical trials.

EXPERT OPINION

Among antiepileptics and antidepressants, duloxetine appeared to have the most detailed safety for the treatment of peripheral neuropathic pain. Over all studies, the most commonly reported adverse effects were dizziness, drowsiness, nausea, and constipation. Only 20.0% of the included studies (N = 90) presented a good description of adverse effects that included a statistical comparison vers usa placebo group. Important methodological improvements must be made to improve the assessment of medication safety in future clinical trials.

Mechanisms of action of currently used antiseizure drugs

Antiseizure drugs (ASDs) prevent the occurrence of seizures; there is no evidence that they have disease-modifying properties. In the more than 160 years that orally administered ASDs have been available for epilepsy therapy, most agents entering clinical practice were either discovered serendipitously or with the use of animal seizure models. The ASDs originating from these approaches act on brain excitability mechanisms to interfere with the generation and spread of epileptic hyperexcitability, but they do not address the specific defects that are pathogenic in the epilepsies for which they are prescribed, which in most cases are not well understood. There are four broad classes of such ASD mechanisms: (1) modulation of voltage-gated sodium channels (e.g. phenytoin, carbamazepine, lamotrigine), voltage-gated calcium channels (e.g. ethosuximide), and voltage-gated potassium channels [e.g. retigabine (ezogabine)]; (2) enhancement of GABA-mediated inhibitory neurotransmission (e.g. benzodiazepines, tiagabine, vigabatrin); (3) attenuation of glutamate-mediated excitatory neurotransmission (e.g. perampanel); and (4) modulation of neurotransmitter release via a presynaptic action (e.g. levetiracetam, brivaracetam, gabapentin, pregabalin). In the past two decades there has been great progress in identifying the pathophysiological mechanisms of many genetic epilepsies. Given this new understanding, attempts are being made to engineer specific small molecule, antisense and gene therapies that functionally reverse or structurally correct pathogenic defects in epilepsy syndromes. In the near future, these new therapies will begin a paradigm shift in the treatment of some rare genetic epilepsy syndromes, but targeted therapies will remain elusive for the vast majority of epilepsies until their causes are identified. This article is part of the special issue entitled 'New Epilepsy Therapies for the 21st Century - From Antiseizure Drugs to Prevention, Modification and Cure of Epilepsy'.

Levetiracetam – a drug that can be used not only in the treatment of epilepsy

Levetiracetam, which belongs to the new generation of antiepileptic drugs, has a unique and not well-known mechanism of action. The drug affects the release of neurotransmitters through the binding to the synaptic vesicle protein SV2A. Moreover, it acts on calcium channels, inhibits glutamatergic neurotransmission and affects GABA-ergic neurotransmission through e.g. the Zn²⁺-induced suppression of GABAA-mediated presynaptic inhibition and the modulation of the action of GABAA antagonists. Levetiracetam has also neuroprotective activity which is associated with the influence on transcription processes, neurotransmission, antioxidant and anti-inflammatory activity. The results of recent research indicate that this complex action creates the prospect of using it in the alleviation of epileptogenesis, poststroke seizuires, seizure prophylaxis in brain injured patients and diabetic neuropathy. Furthermore, the drug may also have a beneficial effect in the treatment of Alzheimer patients with epileptic seizures and levodopa-induced dyskinesias in Parkinson’s disease.

Levetiracetam and brivaracetam: a review of evidence from clinical trials and clinical experience

Until the early 1990s, a limited number of antiepileptic drugs (AEDs) were available. Since then, a large variety of new AEDs have been developed and introduced, several of them offering new modes of action. One of these new AED families is described and reviewed in this article. Levetiracetam (LEV) and brivaracetam (BRV) are pyrrolidone derivate compounds binding at the presynaptic SV2A receptor site and are thus representative of AEDs with a unique mode of action. LEV was extensively investigated in randomized controlled trials and has a very promising efficacy both in focal and generalized epilepsies. Its pharmacokinetic profile is favorable and LEV does not undergo clinically relevant interactions. Adverse reactions comprise mainly asthenia, somnolence, and behavioral symptoms. It has now been established as a first-line antiepileptic drug. BRV has been recently introduced as an adjunct antiepileptic drug in focal epilepsy with a similarly promising pharmacokinetic profile and possibly increased tolerability concerning psychiatric adverse events. This review summarizes the essential preclinical and clinical data of LEV and BRV that is currently available and includes the experiences at a large tertiary referral epilepsy center.

Clinical Presentation and Outcome in Autoimmune Encephalitis Associated With N-Type Voltage-Gated Calcium Channels in Children

OBJECTIVE

We present the diagnostic and clinical course of the first multicenter case series of pediatric patients with autoimmune encephalitis associated with N-type voltage-gated calcium channel antibodies.

METHODS

Data from 2 university hospitals were retrospectively reviewed and records of 3 patients with autoimmune encephalitis associated with N-type voltage-gated calcium channel antibodies were evaluated.

RESULTS

The 3 pediatric patients (all female) had symptoms that spanned the clinical spectrum. All 3, however, had regression of expressive language and agitation. Neuroimaging in all 3 patients was normal; electroencephalographic (EEG) findings varied among the 3 patients. Positive titers against the N-type voltage-gated calcium channel antibody were found in their cerebrospinal fluid. Following administration of intravenous immunoglobulin, all 3 had improvement in their core presenting symptoms.

CONCLUSION

Autoimmune encephalitis associated with N-type voltage-gated calcium channel antibodies in the pediatric population presents with a wide clinical spectrum, although expressive language delay and agitation seem to be common symptoms. Treatment with intravenous immunoglobulin improves core symptoms.

Suppressive effects of levetiracetam on neuroinflammation and phagocytic microglia: A comparative study of levetiracetam, valproate and carbamazepine

We previously reported that treatment with levetiracetam (LEV) after status epilepticus (SE) termination by diazepam (DZP) prevents the development of spontaneous recurrent seizures. LEV suppresses increased expression levels of proinflammatory mediators during epileptogenesis after SE, but how LEV acts in neuroinflammatory processes is not yet known. In this study, we examined the effects of LEV on neuroinflammation and phagocytic microglia in vivo and in vitro and compared the effects of LEV with those of representative antiepileptic drugs valproate (VPA) and carbamazepine (CBZ). Repeated treatment with LEV for 30 days after the termination of pilocarpine-induced SE by DZP almost completely prevented the incidence of spontaneous recurrent seizures, while administration of VPA or CBZ showed no effect on the seizures. LEV clearly suppressed phagocytosis of mononuclear phagocytes, and cytokine expression was observed 2 days after SE. VPA attenuated neuroinflammation only, and CBZ showed no effect on changes after SE. Treatment with LEV significantly suppressed BV-2 microglial activation, which was defined by morphological changes, phagocytic activity and cytokine expression. By contrast, VPA and CBZ did not affect BV-2 microglial activity. In summary, LEV directly suppresses excess microglial phagocytosis during epileptogenesis, which might prevent the occurrence of spontaneous recurrent seizures after SE.

The Protective Effects of Levetiracetam on a Human iPSCs-Derived Spinal Muscular Atrophy Model

Spinal muscular atrophy (SMA) is an inherited disease characterized by progressive motor neuron death and subsequent muscle weakness and is caused by deletion or mutation of survival motor neuron (SMN) 1 gene. Protecting spinal motor neuron is an effective clinical strategy for SMA. The purpose of this study was to investigate the potential effect of an anti-epileptic drug levetiracetam on SMA. In the present study, we used differentiated spinal motor neurons (MNs) from SMA patient-derived induced pluripotent stem cells (SMA-iPSCs) to investigate the effect of levetiracetam. Levetiracetam promoted neurite elongation in SMA-iPSCs-MNs. TUNEL-positive spinal motor neurons were significantly reduced by levetiracetam in SMA-iPSCs-MNs. In addition, the expression level of cleaved-caspase 3 was decreased by levetiracetam in SMA-iPSCs-MNs. Furthermore, levetiracetam improved impaired mitochondrial function in SMA-iPSCs-MNs. On the other hand, levetiracetam did not affect the expression level of SMN protein in SMA-iPSCs-MNs. These findings indicate that levetiracetam has a neuroprotective effect for SMA.

Pharmacokinetic considerations for anti-epileptic drugs in children

INTRODUCTION

Epilepsy is a chronic and debilitating neurological disease, with a peak of incidence in the first years of life. Today, the vast armamentarium of antiepileptic drugs (AEDs) available make even more challenging to select the most appropriate AED and establish the most effective dosing regimen. In fact, AEDs pharmacokinetics is under the influence of important age-related factors which cannot be ignored. Areas covered: Physiological changes occurring during development age (different body composition, immature metabolic patterns, reduced renal activity) can significantly modify the pharmacokinetic profile of AEDs (adsorption, volume of distribution, half-life, clearance), leading to an altered treatment response. We reviewed the main pharmacokinetic characteristics of AEDs used in children, focusing on age-related factors which are of relevance when treating this patient population. Expert opinion: To deal with this pharmacokinetic variability, physicians have at their disposal two tools: 1) therapeutic drug concentration monitoring, which may help to set the optimal therapeutic regimen for each patient and to monitor eventual fluctuation, and 2) the use of extended-release drug formulations, when available. In the next future, the development of 'ad-hoc' electronic dashboard systems will represent relevant decision-support tools making the AED therapy even more individualized and precise, especially in children.

Variability with Astroglial Glutamate Transport Genetics Is Associated with Increased Risk for Post-Traumatic Seizures

Excitotoxicity contributes to epileptogenesis after severe traumatic brain injury (sTBI). Demographic and clinical risk factors for post-traumatic seizures (PTS) have been identified, but genetic risk remains largely unknown. Thus, we investigated whether genetic variation in astroglial glutamate transporter genes is associated with accelerated epileptogenesis and PTS risk after sTBI. Adults (n = 267) 18-75 years old were assessed over a three-year period post-TBI. Single nucleotide polymorphisms (SNPs) throughout the SLC1A2 and SLC1A3 genes were assayed. Kaplan-Meier estimates and log-rank statistics were used to compare seizure frequencies by genotype. Multivariate Cox proportional hazards regression was used to estimate hazard ratios (HRs) for genotypes significant in Kaplan-Meier analyses. Thirty-nine tagging SNPs were examined (SLC1A2: n = 21, SLC1A3: n = 18). PTS developed in 57 (21.4%) individuals. Of those with PTS, n = 20 (35.7%) had an immediate/early seizure within the first seven days, and n = 36 (64.3%) had a late seizure occurring between eight days and three years post-TBI. When adjusting for multiple comparisons, rs4869682 genotypes (SLC1A3, GG vs. T-carriers) were associated with time to first seizure (p = 0.003). Median time until first seizure was 20.4 days for individuals with a GG genotype and 44.8 days for T-carriers. After adjusting for covariates, rs4869682 GG-homozygotes had a 2.05 times increased PTS risk versus T-carriers (aHR = 2.08, 95% confidence interval: 1.20, 3.62, p = 0.009). Variation within SLC1A3 is associated with accelerated epileptogenesis and clinical PTS development after sTBI. Future studies should validate these findings and examine how genetic variation at rs4869682 may be a target for PTS prevention and treatment.

Neuroprotective effects of levetiracetam, both alone and combined with propylparaben, in the long-term consequences induced by lithium-pilocarpine status epilepticus

Status epilepticus (SE) is a neurological condition that frequently induces severe neuronal injury in the hippocampus, subsequent epileptogenesis and pharmacoresistant spontaneous recurrent seizures (SRS). The repeated administration of LEV (a broad-spectrum antiepileptic drug) during the post-SE period does not prevent the subsequent development of SRS. However, this treatment reduces SE-induced neurodegeneration in the hippocampus. Conversely, propylparaben (PPB) is a widely used antimicrobial that blocks voltage-dependent Na⁺ channels, induces neuroprotection and reduces epileptiform activity in vitro. The present study attempted to determine if the neuroprotective effects induced by LEV are augmented when combined with a sub-effective dose of PPB. Long-term SE-induced consequences (hyperexcitability, high glutamate release, neuronal injury and volume loss) were evaluated in the hippocampus of rats. LEV alone, as well as combined with PPB, did not prevent the occurrence of SRS. However, animals treated with LEV plus PPB showed high prevalence of low frequency oscillations (0.1-4 Hz and 8-90 bands, p < 0.001) and low prevalence of high frequency activity (90-250 bands, p < 0.001) during the interictal period. In addition, these animals presented lower extracellular levels of glutamate, decreased rate of neurodegeneration and a similar hippocampal volume compared to the control conditions. This study's results suggest that LEV associated with PPB could represent a new therapeutic strategy to reduce long-term consequences induced by SE that facilitate pharmacoresistant SRS.