Effect of perampanel, a novel AMPA antagonist, on benzodiazepine-resistant status epilepticus in a lithium-pilocarpine rat model

Use of perampanel oral suspension for the treatment of refractory and super-refractory status epilepticus

INTRODUCTION

Status epilepticus (SE) is a medical emergency associated with a significant risk of disability and death. The treatment of SE follows a step-wise approach, with limited data on ideal antiseizure medications (ASMs) for refractory and super refractory SE (RSE/SRSE). Perampanel (PER), an AMPA receptor antagonist, has shown promise in animal models but still has limited data in humans. This study tried to evaluate optimal dosage and safety of PER in RSE and SRSE patients.

MATERIALS AND METHODS

We retrospectively analysed 17 adult patients with RSE (1) or SRSE (16) treated with PER. Demographic and clinical data, including EEG patterns, ASMs administered, PER dosages, and PER plasma concentrations, were collected. For patients receiving a 24 mg PER loading dose (full dose group), the following treatment regimen was applied: 24 mg per day for 48 h following by 16 mg per day. The response to PER was assessed based on electroencephalographic (EEG) improvement from high to low epileptiform activity or from low to the absence of epileptiform activities. Safety was evaluated monitoring hepatic and renal function.

RESULTS

A response rate of 58.82 % was observed, with significantly higher responses in the full dose group (81.82 %) compared to those receiving PER doses below 24 mg (low dose group) (16.67 %) (p-value = 0.004; OR 0.044, 95 % CI 0.003 to 0.621, p = 0.021). No other clinical factors significantly influenced treatment response. Hepatic enzymes become elevated in most patients (70.59 %) but spontaneously decreased.

DISCUSSION

Our findings suggest that a 24 mg PER dose administered for 48 h may be more effective in managing RSE and SRSE compared to doses below 24 mg, potentially due to pharmacokinetic factors.

CONCLUSION

More robust data on PER in RSE and SRSE, including standardized dosing procedures and plasma level monitoring are needed. PER's potential benefits should be explored further, particularly in patients with RSE and SRSE.

Efficacy of Perampanel in Refractory and Super-Refractory Status Epilepticus with Suspected Inflammatory Etiology: A Case Series

(1) Background: Increasing evidence supports the anti-inflammatory and neuroprotective role of perampanel (PER), mediated by decreased expression of pro-inflammatory cytokines and by interference with apoptosis processes. Therefore, the use of PER to treat status epilepticus (SE) with suspected inflammatory etiology is appealing and deserves further investigation. (2) Methods: We retrospectively analyzed seven patients (five F, two M; median age: 62 years) with refractory and super-refractory SE due to a probable or defined inflammatory etiology and treated with PER. (3) Results: PER was administered as the third (4/7) or fourth drug (3/7), with a median loading dose of 32 mg/day (range: 16-36 mg/day) and a median maintenance dose of 10 mg/day (range: 4-12 mg/day). In five cases, SE was focal, while in two patients, it was generalized. SE was caused by systemic inflammation in three patients, while in the other four subjects, it was recognized to have an autoimmune etiology. SE resolution was observed after PER administration in all cases, particularly within 24 h in the majority of patients (4/7, 57.1%). (4) Conclusions: Our data support the efficacy of PER in treating SE when first- and second-line ASMs have failed and suggest a possible earlier use in SE cases that are due to inflammatory/autoimmune etiology.

Parkinson's disease, epilepsy, and amyotrophic lateral sclerosis-emerging role of AMPA and kainate subtypes of ionotropic glutamate receptors

Ionotropic glutamate receptors (iGluRs) mediate the majority of excitatory neurotransmission and are implicated in various neurological disorders. In this review, we discuss the role of the two fastest iGluRs subtypes, namely, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and kainate receptors, in the pathogenesis and treatment of Parkinson's disease, epilepsy, and amyotrophic lateral sclerosis. Although both AMPA and kainate receptors represent promising therapeutic targets for the treatment of these diseases, many of their antagonists show adverse side effects. Further studies of factors affecting the selective subunit expression and trafficking of AMPA and kainate receptors, and a reasonable approach to their regulation by the recently identified novel compounds remain promising directions for pharmacological research.

Anti-seizure efficacy of perampanel in two established rodent models of early-life epilepsy

Early-life seizures can be refractory to conventional antiseizure medications (ASMs) and can also result in chronic epilepsy and long-term behavioral and cognitive deficits. Treatments targeting age-specific mechanisms contributing to epilepsy would be of clinical benefit. One such target is the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) subtype of excitatory glutamate receptor, which is upregulated in the developing brain. Perampanel is a non-competitive, selective AMPAR antagonist that is FDA-approved for focal onset seizures (FOS) or primary generalized tonic-clonic seizures (PGTC) in children and adults. However, the efficacy of perampanel treatment in epilepsy patients younger than 4 years has been less documented. We thus tested the efficacy of perampanel in two early-life seizure models: (1) a rat model of hypoxia-induced neonatal seizures and (2) a mouse model of Dravet syndrome with hyperthermia-induced seizures. Pretreatment with perampanel conferred dose-dependent protection against early-life seizures in both experimental models. These findings suggest that AMPAR-mediated hyperexcitability could be involved in the pathophysiology of early-life seizures, which may be amenable to treatment with perampanel.

The Role of Glutamate Receptors in Epilepsy

Glutamate is an essential excitatory neurotransmitter in the central nervous system, playing an indispensable role in neuronal development and memory formation. The dysregulation of glutamate receptors and the glutamatergic system is involved in numerous neurological and psychiatric disorders, especially epilepsy. There are two main classes of glutamate receptor, namely ionotropic and metabotropic (mGluRs) receptors. The former stimulate fast excitatory neurotransmission, are N-methyl-d-aspartate (NMDA), α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA), and kainate; while the latter are G-protein-coupled receptors that mediate glutamatergic activity via intracellular messenger systems. Glutamate, glutamate receptors, and regulation of astrocytes are significantly involved in the pathogenesis of acute seizure and chronic epilepsy. Some glutamate receptor antagonists have been shown to be effective for the treatment of epilepsy, and research and clinical trials are ongoing.

The Roles of Glutamate Receptors and Their Antagonists in Status Epilepticus, Refractory Status Epilepticus, and Super-Refractory Status Epilepticus

Status epilepticus (SE) is a neurological emergency with a high mortality rate. When compared to chronic epilepsy, it is distinguished by the durability of seizures and frequent resistance to benzodiazepine (BZD). The Receptor Trafficking Hypothesis, which suggests that the downregulation of γ-Aminobutyric acid type A (GABAA) receptors, and upregulation of N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors play major roles in the establishment of SE is the most widely accepted hypothesis underlying BZD resistance. NMDA and AMPA are ionotropic glutamate receptor families that have important excitatory roles in the central nervous system (CNS). They are both essential in maintaining the normal function of the brain and are involved in a variety of neuropsychiatric diseases, including epilepsy. Based on animal and human studies, antagonists of NMDA and AMPA receptors have a significant impact in ending SE; albeit most of them are not yet approved to be in clinically therapeutic guidelines, due to their psychomimetic adverse effects. Although there is still a dearth of randomized, prospective research, NMDA antagonists such as ketamine, magnesium sulfate, and the AMPA antagonist, perampanel, are regarded to be reasonable optional adjuvant therapies in controlling SE, refractory SE (RSE) or super-refractory SE (SRSE), though there are still a lack of randomized, prospective studies. This review seeks to summarize and update knowledge on the SE development hypothesis, as well as clinical trials using NMDA and AMPA antagonists in animal and human studies of SE investigations.

Double antiglutamatergic treatment in patients with status epilepticus: A case series

INTRODUCTION

Status epilepticus (SE) continues to be a challenging neurological emergency with high morbidity and mortality. During treatment, different regimens are practiced encompassing all known seizure termination mechanisms. To our knowledge, this is the first case series report describing EEG patterns and clinical outcomes in patients treated with ketamine and perampanel (PER) concomitantly.

OBJECTIVE

To assess clinical and electrographic outcomes in patients receiving dual antiglutamatergic therapy in SE.

RESULTS

Twenty-one out of twenty five patients were treated with ketamine, and four patients with ketamine were associated with PER. In the ketamine plus PER group, three out of four patients had convulsive SE, and one had non-convulsive status epilepticus (NCSE), whereas eight patients in the ketamine group had NCSE. The incidence of beta pattern appearance on EEG after starting patients on ketamine and PER was achieved in all four patients (100%) compared to (61.9%) in the other group. A burst suppression pattern was recorded in 75% of patients treated with ketamine and PER, in comparison to 28.5% of patients in patients treated with a different regimen. The time to resolution of SE was significantly shorter in the ketamine group (median 24 (24-64) h vs. 6 (05-144) h p > 0.05). Moreover, the average number of days on IV anesthetic was slightly lower in a patient treated with PER concomitantly. In terms of morbidity, the average increase in mRS was also lower in the ketamine and PER group, although it was not statistically significant.

CONCLUSIONS

Dual anti-glutamatergic therapy could provide a favorable approach to treating SE, which yet needs to be further investigated through larger randomized control studies.

A retrospective, real-world experience of perampanel monotherapy in patient with first new onset focal seizure: A Thailand experience

Objective

Real‐world data on efficacy and tolerability of perampanel (PER) monotherapy in treatment‐naïve patients with focal onset seizures (FOS) and/or focal‐to‐bilateral tonic‐clonic seizures (FBTCS) to assess efficacy effectiveness and tolerability.

Methods

This is a retrospective review of study patients with new FOS with or without FBTCS, aged ≥15 years, who had been prescribed PER as monotherapy. Treatment outcome included retention rate, responder, and seizure‐free rate at observational point 3, 6, and 12 months (OP3, OP6, and OP12). Treatment‐emergent adverse events (TEAEs) and adverse drug reactions were recorded.

Results

A total of 41 patients enrolled in the study (male:female; 17:22, mean age =46.1 ± 21.8 years), with new FOS and/or FBTCS. The proportions of individuals remaining on PER monotherapy at 3, 6, and 12 months were evaluated. The median PER dosage was 4 mg (range 2‐8 mg). The retention rates at OP3, OP6, and OP12 were 88%, 73%, and 61%, respectively. The seizure freedom rates at OP3, OP6, and OP12 were 78%, 80%, and 76%, respectively. About 14% had discontinued the PER monotherapy because of lack of efficacy. Sixteen individuals (41%) had TEAEs; common AEs were dizziness, somnolence, and ataxia; and only one case had depression. The AEs with somnolence and ataxia were found higher in elderly (15% and 30%) than adult patients (7% and 3%), respectively. Only 14% had intolerant adverse events, and it was found higher in elderly (23%).

Significance

Real‐world data of PER monotherapy in treatment‐naïve patients with focal onset seizures demonstrated good effectiveness and a good safety profile at relatively low doses. By starting with low dosage and slow titration of PER help to minimize the impact of adverse effects, maximize adherence, and increase patient retention. PER has a once‐daily dosing schedule that supports patient adherence contributes to achieving seizure freedom.

Perampanel Reduces Hyperthermia-Induced Seizures in Dravet Syndrome Mouse Model

Treatment options for Dravet syndrome are limited. The aim of this study was to evaluate the antiepileptic effect of the AMPA receptor antagonist perampanel (PER) on a mouse model of Dravet syndrome (Scn1a^E1099X/+). We report here that the PER (2 mg/kg) treatment inhibited the spontaneous recurrent seizures and attenuated epileptic activity in Scn1a^E1099X/+ mice. In the hyperthermia-induced seizure experiment, PER clearly increased temperature tolerance and significantly ameliorated seizure frequency and discharge duration. PER also demonstrated antiepileptic effects in a cross-over study and a synergistic effect for attenuating heat-induced seizure when given in combination with stiripentol or valproic acid. The results showed that PER effectively decreased the occurrence of spontaneous recurrent seizures and showed significant therapeutic potential for hyperthermia-induced seizures with regard to both susceptibility and severity in a Dravet syndrome mouse model. Potential therapeutic effects of PER for treatment of Dravet syndrome were demonstrated.

Perampanel, a potent AMPA receptor antagonist, protects against tetramethylenedisulfotetramine-induced seizures and lethality in mice: comparison with diazepam

Tetramethylenedisulfotetramine (TETS), a noncompetitive GABA_A receptor antagonist, is a potent, highly lethal convulsant that is considered to be a chemical threat agent. Here, we assessed the ability of the AMPA receptor antagonist perampanel to protect against TETS-induced seizures and lethality in mice when administered before or after treatment with the toxicant. For comparison, we conducted parallel testing with diazepam, which is a first-line treatment for chemically induced seizures in humans. Pre-treatment of mice with either perampanel (1–4 mg/kg, i.p.) or diazepam (1–5 mg/kg, i.p.) conferred protection in a dose-dependent fashion against tonic seizures and lethality following a dose of TETS (0.2 mg/kg, i.p.) that rapidly induces seizures and death. The ED₅₀ values for protection against mortality were 1.6 mg/kg for perampanel and 2.1 mg/kg for diazepam. Clonic seizures were unaffected by perampanel and only prevented in a minority of animals by high-dose diazepam. Neither treatment prevented myoclonic body twitches. Perampanel and diazepam also conferred protection against tonic seizures and lethality when administered 15 min following a 0.14 mg/kg, i.p., dose of TETS and 5 min following a 0.2 mg/kg, i.p., dose of TETS. Both posttreatments were highly potent at reducing tonic seizures and lethality in animals exposed to the lower dose of TETS whereas greater doses of both treatments were required in animals exposed to the larger dose of TETS. Neither treatment was as effective suppressing clonic seizures. In an experiment where 0.4 mg/kg TETS was administered by oral gavage and the treatment drugs were administered 5 min later, perampanel only partially protected against lethality whereas diazepam produced nearly complete protection. We conclude that perampanel and diazepam protect against TETS-induced tonic seizures and lethality but have less impact on clonic seizures. Both drugs could have utility in the treatment of TETS intoxication but neither eliminates all seizure activity.

Efficacy and safety of perampanel in refractory and super-refractory status epilepticus: cohort study of 81 patients and literature review

BACKGROUND

The effective dose of perampanel in status epilepticus (SE), refractory SE (RSE), and super-refractory SE (SRSE) in humans is unknown, and the potential of perampanel in treating SE has not been evaluated in a large cohort.

METHODS

Data of intensive care patients with RSE and SRSE treated with perampanel were retrospectively reviewed and analyzed.

RESULTS

Eighty-one patients received perampanel, including 39 females with median age 64 [17-91] years, perampanel responders (n = 27), and non-responders (n = 54). The initial perampanel dose was positively associated with treatment response in patients with RSE or SRSE (OR = 1.27, 95% CI 1.03-1.57, p = 0.025), while the maximum dose was negatively associated with treatment response (OR = 0.74, 95% CI 0.58-0.96, p = 0.022). Hypoxia caused seizures in six patients; five died in hospital and one had severe disability. A statistically non-significant tendency toward better response was found in patients with unique SE type and cause, particularly in nonconvulsive status epilepticus (NCSE) without coma (NCSE without coma vs. generalized tonic-clonic seizure: OR = 4.14, 95% CI 0.98-17.47, p = 0.053). In the high-dose (≥ 16 mg/day) groups, although distributions of modified Rankin Scale (mRS) scores were similar between perampanel responders and non-responders at discharge, a greater proportion of perampanel responders had less change in mRS scores from baseline than did perampanel non-responders (median mRS: 0 vs 4, p = 0.064). No cardiorespiratory adverse events or laboratory abnormalities were noted with perampanel treatment.

CONCLUSIONS

Perampanel is effective and has a satisfactory safety profile in the emergency treatment of established RSE and SRSE.

Management of status epilepticus in patients with liver or kidney disease: a narrative review

Introduction: Status epilepticus (SE) is a neurologic and medical emergency with significant related morbidity and mortality. Hepatic or renal dysfunction can considerably affect the pharmacokinetics of drugs used for SE through a variety of direct or indirect mechanisms.Areas Covered: This review aims to focus on the therapeutic management of SE in patients with hepatic or renal impairment, highlighting drugs' selection and dose changes that may be necessary due to altered drug metabolism and excretion. The references for this review were identified by searches of PubMed and Google Scholar until May 2020.Expert opinion: According to literature evidence and clinical experience, in patients with renal disease, the authors suggest considering lorazepam as the drug of choice in pre-hospital and intra-hospital early-stage SE, phenytoin in definite SE, propofol in refractory or super-refractory SE. In patients with liver disease, the authors suggest the use of lorazepam as drug of choice in pre-hospital and intra-hospital early-stage SE, lacosamide in definite SE, propofol in refractory or super-refractory SE. A list of preferred drugs for all SE stages is provided.

Src/CK2/PTEN-Mediated GluN2B and CREB Dephosphorylations Regulate the Responsiveness to AMPA Receptor Antagonists in Chronic Epilepsy Rats

Both α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor (AMPAR) and N-methyl-D-aspartate receptor (NMDAR) have been reported as targets for treatment of epilepsy. To investigate the roles and interactions of AMPAR and NMDAR in ictogenesis of epileptic hippocampus, we analyzed AMPAR antagonists (perampanel and GYKI 52466)-mediated phosphatase and tensin homolog deleted on chromosome 10 (PTEN) regulation and glutamate ionotropic receptor NMDA type subunit 2B (GluN2B) tyrosine (Y) 1472 phosphorylation in epilepsy rats. Both perampanel and GYKI 52466 increased PTEN expression and its activity (reduced phosphorylation), concomitant with decreased activities (phosphorylations) of Src family-casein kinase 2 (CK2) signaling pathway. Compatible with these, they also restored the upregulated GluN2B Y1472 and Ca2+/cAMP response element-binding protein (CREB) serine (S) 133 phosphorylations and surface expression of glutamate ionotropic receptor AMPA type subunit 1 (GRIA1) to basal level in the epileptic hippocampus. These effects of perampanel and GYKI 52466 are observed in responders (whose seizure activities are responsive to AMPAR antagonists), but not non-responders (whose seizure activities were uncontrolled by AMPAR antagonists). Therefore, our findings suggest that Src/CK2/PTEN-mediated GluN2B Y1472 and CREB S133 regulations may be one of the responsible signaling pathways for the generation of refractory seizures in non-responders to AMPAR antagonists.

Allopregnanolone and perampanel as adjuncts to midazolam for treating diisopropylfluorophosphate-induced status epilepticus in rats

Combinations of midazolam, allopregnanolone, and perampanel were assessed for antiseizure activity in a rat diisopropylfluorophosphate (DFP) status epilepticus model. Animals receiving DFP followed by atropine and pralidoxime exhibited continuous high-amplitude rhythmical electroencephalography (EEG) spike activity and behavioral seizures for more than 5 hours. Treatments were administered intramuscularly 40 min after DFP. Seizures persisted following midazolam (1.8 mg/kg). The combination of midazolam with either allopregnanolone (6 mg/kg) or perampanel (2 mg/kg) terminated EEG and behavioral status epilepticus, but the onset of the perampanel effect was slow. The combination of midazolam, allopregnanolone, and perampanel caused rapid and complete suppression of EEG and behavioral seizures. In the absence of DFP, animals treated with the three-drug combination were sedated but not anesthetized. Animals that received midazolam alone exhibited spontaneous recurrent EEG seizures, whereas those that received the three-drug combination did not, demonstrating antiepileptogenic activity. All combination treatments reduced neurodegeneration as assessed with Fluoro-Jade C staining to a greater extent than midazolam alone, and most reduced astrogliosis as assessed by GFAP immunoreactivity but had mixed effects on markers of microglial activation. We conclude that allopregnanolone, a positive modulator of the GABAA receptor, and perampanel, an AMPA receptor antagonist, are potential adjuncts to midazolam in the treatment of benzodiazepine-refractory organophosphate nerve agent-induced status epilepticus.

Ionotropic Glutamate Receptors in Epilepsy: A Review Focusing on AMPA and NMDA Receptors

It is widely accepted that glutamate-mediated neuronal hyperexcitation plays a causative role in eliciting seizures. Among glutamate receptors, the roles of N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors in physiological and pathological conditions represent major clinical research targets. It is well known that agonists of NMDA or AMPA receptors can elicit seizures in animal or human subjects, while antagonists have been shown to inhibit seizures in animal models, suggesting a potential role for NMDA and AMPA receptor antagonists in anti-seizure drug development. Several such drugs have been evaluated in clinical studies; however, the majority, mainly NMDA-receptor antagonists, failed to demonstrate adequate efficacy and safety for therapeutic use, and only an AMPA-receptor antagonist, perampanel, has been approved for the treatment of some forms of epilepsy. These results suggest that a misunderstanding of the role of each glutamate receptor in the ictogenic process may underlie the failure of these drugs to demonstrate clinical efficacy and safety. Accumulating knowledge of both NMDA and AMPA receptors, including pathological gene mutations, roles in autoimmune epilepsy, and evidence from drug-discovery research and pharmacological studies, may provide valuable information enabling the roles of both receptors in ictogenesis to be reconsidered. This review aimed to integrate information from several studies in order to further elucidate the specific roles of NMDA and AMPA receptors in epilepsy.

Pharmacotherapy for Pediatric Convulsive Status Epilepticus

Convulsive status epilepticus (CSE) is one of the most common pediatric neurological emergencies. Ongoing seizure activity is a dynamic process and may be associated with progressive impairment of gamma-aminobutyric acid (GABA)-mediated inhibition due to rapid internalization of GABA_A receptors. Further hyperexcitability may be caused by AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) and NMDA (N-methyl-D-aspartic acid) receptors moving from subsynaptic sites to the synaptic membrane. Receptor trafficking during prolonged seizures may contribute to difficulties treating seizures of longer duration and may provide some of the pathophysiological underpinnings of established and refractory SE (RSE). Simultaneously, a practice change toward more rapid initiation of first-line benzodiazepine (BZD) treatment and faster escalation to second-line non-BZD treatment for established SE is in progress. Early administration of the recommended BZD dose is suggested. For second-line treatment, non-BZD anti-seizure medications (ASMs) include valproate, fosphenytoin, or levetiracetam, among others, and at this point there is no clear evidence that any one of these options is better than the others. If seizures continue after second-line ASMs, RSE is manifested. RSE treatment consists of bolus doses and titration of continuous infusions under continuous electro-encephalography (EEG) guidance until electrographic seizure cessation or burst-suppression. Ultimately, etiological workup and related treatment of CSE, including broad spectrum immunotherapies as clinically indicated, is crucial. A potential therapeutic approach for future studies may entail consideration of interventions that may accelerate diagnosis and treatment of SE, as well as rational and early polytherapy based on synergism between ASMs by utilizing medications targeting different mechanisms of epileptogenesis and epileptogenicity.

Super-Refractory Status Epilepticus Treated with High Dose Perampanel: Case Series and Review of the Literature

Introduction

Acute symptomatic seizures are frequent in the critically ill patient and can be difficult to treat. The novel anticonvulsant perampanel may be effective in the treatment of status epilepticus considering its mechanism of action of being an AMPA antagonist. We present four cases of super refractory status epilepticus treated with high dose perampanel.

Method

Case report.

Cases

Four patients were treated with perampanel for their refractory status epilepticus. One patient had new onset refractory status epilepticus of unknown etiology. Three other patients had status epilepticus as a result of their cardiac arrest. Two of the cardiac arrest patients had myoclonus. In all patients, the additional of perampanel resulted in a reduction of seizure burden without affecting hemodynamics or hepatic or renal function.

Conclusion

Perampanel may be effective in the treatment of super-refractory status epilepticus of varying etiologies. A larger, prospective study is needed to further assess this therapy.

Pharmacotherapy for Refractory and Super-Refractory Status Epilepticus in Adults

Patients with prolonged seizures that do not respond to intravenous benzodiazepines and a second-line anticonvulsant suffer from refractory status epilepticus and those with seizures that do not respond to continuous intravenous anesthetic anticonvulsants suffer from super-refractory status epilepticus. Both conditions are associated with significant morbidity and mortality. A strict pharmacological treatment regimen is urgently required, but the level of evidence for the available drugs is very low. Refractory complex focal status epilepticus generally does not require anesthetics, but all intravenous non-anesthetizing anticonvulsants may be used. Most descriptive data are available for levetiracetam, phenytoin and valproate. Refractory generalized convulsive status epilepticus is a life-threatening emergency, and long-term clinical consequences are eminent. Administration of intravenous anesthetics is mandatory, and drugs acting at the inhibitory gamma-aminobutyric acid (GABA)_A receptor such as midazolam, propofol and thiopental/pentobarbital are recommended without preference for one of those. One in five patients with anesthetic treatment does not respond and has super-refractory status epilepticus. With sustained seizure activity, excitatory N-methyl-d-aspartate (NMDA) receptors are increasingly expressed post-synaptically. Ketamine is an antagonist at this receptor and may prove efficient in some patients at later stages. Neurosteroids such as allopregnanolone increase sensitivity at GABA_A receptors; a Phase 1/2 trial demonstrated safety and tolerability, but randomized controlled data failed to demonstrate efficacy. Adjunct ketogenic diet may contribute to termination of difficult-to-treat status epilepticus. Randomized controlled trials are needed to increase evidence for treatment of refractory and super-refractory status epilepticus, but there are multiple obstacles for realization. Hitherto, prospective multicenter registries for pharmacological treatment may help to improve our knowledge.

Perampanel for treatment of status epilepticus in Austria, Finland, Germany, and Spain

OBJECTIVE

Novel treatments are needed to control treatment-resistant status epilepticus (SE). We report a summary of clinical cases where perampanel was used in established SE, refractory SE (RSE), or super-refractory SE (SRSE).

METHODS

Medical records were retrospectively reviewed for perampanel administration in SE at five European hospitals between 2011 and 2015.

RESULTS

Of 1319 patients identified as experiencing SE, 52 (3.9%) received perampanel. Median latency from SE onset to perampanel initiation was 10 days. Patients with SE had previously failed benzodiazepines (when received) and a median of five other antiepileptic drugs (AEDs). Median initial perampanel dose was 6 mg/d, up-titrated to a median maximum dose of 10 mg/d. Perampanel was the last drug added in 32/52 (61.5%) patients, with response attributed to perampanel in 19/52 (36.5%) patients. A greater proportion of perampanel non-responders had SRSE (51.5%; 17/33) vs perampanel responders (31.6%; 6/19), and had failed a higher mean number of AEDs before initiating perampanel (5.9 vs 5.1, respectively). Most commonly reported adverse effects during perampanel treatment were dizziness (n = 1 [1.9%]) and somnolence (n = 1 [1.9%]). No serious adverse effects were documented, and none led to discontinuation of perampanel.

CONCLUSIONS

Perampanel was administered to patients with established SE, RSE, or SRSE at greater initial doses than those administered in clinical practice to patients with epilepsy. The SE cases reported here represent a refractory and heterogeneous population, and rate of seizure cessation attributed to perampanel treatment (36.5%) represents a notable response. These data should be confirmed in a larger patient population.

Antiseizure medications in critical care: an update

PURPOSE OF REVIEW

Seizures and status epilepticus are very common diagnoses in the critically ill patient and are associated with significant morbidity and mortality. There is an abundance of research on the utility of antiseizure medications in this setting, but limited randomized-controlled trials to guide the selection of medications in these patients. This review examines the current guidelines and treatment strategies for status epilepticus and provides an update on newer antiseizure medications in the critical care settings.

RECENT FINDINGS

Time is brain applies to status epilepticus, with delays in treatment corresponding with worsened outcomes. Establishing standardized treatment protocols within a health system, including prehospital treatment, may lead to improved outcomes. Once refractory status epilepticus is established, continuous deep sedation with intravenous anesthetic agents should be effective. In cases, which prove highly refractory, novel approaches should be considered, with recent data suggesting multiple recently approved antiseizure medications, appropriate therapeutic options, as well as novel approaches to upregulate extrasynaptic γ-aminobutyric acid channels with brexanolone.

SUMMARY

Although there are many new treatments to consider for seizures and status epilepticus in the critically ill patient, the most important predictor of outcome may be rapid diagnosis and treatment. There are multiple new and established medications that can be considered in the treatment of these patients once status epilepticus has become refractory, and a multidrug regimen will often be necessary.

Perampanel in the treatment of status epilepticus: A systematic review of the literature

OBJECTIVE

Perampanel (PER) is a noncompetitive β-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-yl)propionic acid (AMPA) receptor antagonist with demonstrated efficacy in animal models of status epilepticus (SE). We performed a systematic review of the literature to assess the efficacy and tolerability of PER in the treatment of refractory and super-refractory SE.

METHODS

We searched Medline, Embase, and CENTRAL (accessed from inception to April 30, 2018) to identify studies evaluating oral PER as treatment of SE of any type. We also searched the OpenGrey repository and conference proceedings of international congresses by the International League Against Epilepsy and by the American Epilepsy Society from 2012 onwards.

RESULTS

Ten articles were included, with a total of 69 episodes of SE occurring in 68 patients (aged 18 to 91 years). The type and etiology of SE varied remarkably across studies. The number of drugs used prior to PER ranged from 1 to 9. The time from SE onset to PER administration ranged from 9.25 h to 35 days. The initial PER dose ranged from 2 to 32 mg. The proportion of patients achieving clinical SE cessation varied from 17% to 100%. The time from PER administration to SE cessation ranged from 1 h to 4 weeks.

CONCLUSIONS

The currently available evidence supporting the use of PER in SE is weak and hampered by several confounding factors. Further studies should be performed in more clinically homogeneous and larger cohorts to evaluate the efficacy and safety of PER administered in earlier stages of SE, at higher dosages, and at intervals shorter than 24 h.

Novel drugs and early polypharmacotherapy in status epilepticus

PURPOSE

Rescue medications for status epilepticus (SE) have a relatively high rate of failure. The purpose of this review is to summarize the evidence for the efficacy of novel drugs and early polypharmacotherapy for SE.

METHOD

Literature review.

RESULTS

New drugs and treatment strategies aim to target the pathophysiology of SE in order to improve seizure control and outcomes. Changes at the synapse level during SE include a progressive decrease in synaptic GABA_A receptors and increase in synaptic NMDA receptors. These changes tend to promote self-sustaining seizures. Current SE guidelines recommend a rapid stepwise treatment using benzodiazepines in monotherapy as the first-line treatment, targeting GABA_A synaptic receptors. Novel treatment approaches target GABA_A synaptic and extrasynaptic receptors with allopregnanolone, and NMDA receptors with ketamine. Novel rescue treatments used for SE include topiramate, brivaracetam, and perampanel, which are already marketed in epilepsy. Some available drugs not marketed for use in epilepsy have been used in the treatment of SE, and other agents are being studied for this purpose. Early polytherapy, most frequently combining a benzodiazepine with a second-line drug or an NMDA receptor antagonist, might potentially increase seizure control with relatively minor increase in side effects. Although many preclinical studies support novel drugs and early polytherapy in SE, human studies are scarce and inconclusive. Currently, evidence is lacking to recommend specific combinations of these new agents.

CONCLUSIONS

Novel drugs and strategies target the underlying pathophysiology of SE with the intent to improve seizure control and outcomes.

Perampanel in patients with refractory and super-refractory status epilepticus in a neurological intensive care unit: A single-center audit of 30 patients

In refractory status epilepticus (SE), γ-aminobutyric acidergic drugs become less effective and glutamate plays a major role in seizure perpetuation. Data on the efficacy of perampanel (PER) in treatment of refractory SE in humans are limited. Here, we present a single-center case series of patients with refractory SE who received PER orally in an intensive care unit. We retrospectively analyzed treatment response, outcome, and adverse effects of all patients with refractory SE in our Neurological Intensive Care Unit who received add-on PER between September 2012 and February 2018. Thirty patients with refractory SE (median = 72 years, range = 18-91, 77% women) were included. In 14 patients (47%), a high-dose approach was used, with a median initial dose of 24 mg (range = 16-32). In five patients (17%), SE could be terminated after PER administration (median dose = 6 mg, range = 6-20 mg, 2/5 patients in high-dose group). Clinical response was observed after a median of 24 hours (range = 8-48 hours), whereas electroencephalogram resolved after a median of 60 hours (range = 12-72 hours). Time to treatment response tended to be shorter in patients receiving high-dose PER (median clinical response = 16 hours vs 18 hours; electroencephalographic response = 24 hours vs 72 hours), but groups were too small for statistical analysis. Continuous cardiorespiratory monitoring showed no changes in cardiorespiratory function after "standard" and "high-dose" treatment. Elevated liver enzymes without clinical symptoms were observed after a median of 6 days in seven of 30 patients (23%; 57% high dose vs 43% standard dose), of whom six also received treatment with phenytoin (PHT). Outcome was unfavorable (death, persistent vegetative state) in 13 patients (43%; 39% high dose vs 61% standard dose), and good recovery (no significant disability, moderate disability) was achieved in nine patients (56% high dose vs 44% standard dose). Oral PER in loading doses up to 32 mg were well tolerated but could terminate SE only in a few patients (5/30; 17%). Long duration of SE, route of administration, and severe underlying brain dysfunction might be responsible for the modest result. An intravenous formulation is highly desired to explore the full clinical utility in the treatment of refractory SE.

Perampanel but Not Amantadine Prevents Behavioral Alterations and Epileptogenesis in Pilocarpine Rat Model of Status Epilepticus

Pilocarpine-induced status epilepticus (SE), which results in the development of spontaneous recurrent seizures (SRSs) activates glutamatergic receptors that contribute to seizure sustenance and neuronal cell death. In the current study, we evaluate whether the exposure to perampanel, an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor blocker, or amantadine, a N-methyl-D-aspartic acid (NMDA) receptor blocker would reduce the SE-induced long-term consequences. SE was induced in adult male Sprague Dawley rats with pilocarpine. Perampanel or amantadine was injected 10 or 60 min after SE onset. The efficacy of either, in overcoming pilocarpine-induced SE was assessed using electroencephalogram (EEG) recordings. In addition, alterations in cognitive function, development of spontaneous recurrent seizures (SRSs), and hippocampal damage that are generally encountered after SE were also assessed at 72 h and 5 weeks after the induction of SE. Our results indicate that both early and late treatment with perampanel but not amantadine significantly reduced seizure activity. Furthermore, perampanel but not amantadine, reversed the memory deficits in Y-maze and novel object recognition (NOR) tests and retarded the appearance of SRSs. Moreover, perampanel treatment led to reduced SE-induced caspase-3 activation in the hippocampal lysates. Taken together, the data obtained from the study reveals that blocking AMPA receptors by perampanel can modify SE-induced long-term consequences. Our results may provide a proof of principle for the potential therapeutic application of perampanel in clinical use for status epilepticus in future.

Perampanel: Does it have broad-spectrum potential?

This article reviews the profile of perampanel, a novel noncompetitive α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA) receptor antagonist, and its role as a potential broad-spectrum antiepileptic drug in the treatment of epilepsy. For this narrative review, data were collected using specified search criteria. Articles reporting the evidence for perampanel's efficacy from preclinical models, phase 3 clinical studies, observational studies, and descriptive evidence were included. AMPA receptors play a key role in mediating the action of glutamate at the excitatory synapse. Preclinical research showed the AMPA receptor blockade to constitute a promising target for antiepileptic drug therapy. In animal models, perampanel proved to be protective against seizures and reduce seizure severity and duration. Four phase-3 randomized controlled trials (3 in patients with focal seizures and one in primary generalized tonic-clonic seizures in idiopathic generalized epilepsy) have been completed. In focal (partial) onset seizures, perampanel (4, 8, and 12 mg) significantly reduced seizure frequency per 28 days (23.3%-28.8% vs 12.8%; P < .01) and responder rates (≥50% reduction in seizures) (28.5%-35.3% vs 19.3%; P < .05) compared with placebo. In primary generalized tonic-clonic seizures, perampanel 8 mg resulted in greater reduction in seizure frequency per 28 days (-76.5% vs -38.4%; P < .0001) and responder rate (64.2% vs 39.5%; P = .0019) than placebo. The efficacy, safety, and tolerability of perampanel have been reproduced in real-world clinical practice, and the agent has been shown to be effective in other epilepsy syndromes. Perampanel is a potentially broad-spectrum antiepileptic drug with a novel mechanism of action that may be a useful addition for patients with epilepsy with various seizure types. The availability of novel antiepileptic drugs for epilepsy treatment enables more individualized treatment for these patients.

Flupirtine and diazepam combination terminates established status epilepticus: results in three rodent models

Objective

Status epilepticus (SE) is a neurological emergency requiring rapid termination of seizures. New treatment choices are needed for benzodiazepine-refractory SE or established SE (ESE). Previous studies have demonstrated that the potassium-channel opener flupirtine terminates seizures in neonatal animals. However, its effectiveness in adult ESE has not been tested. We tested whether flupirtine alone or in combination with the benzodiazepine diazepam would terminate ESE in three animal models.

Methods

SE was induced by administration of lithium followed by pilocarpine, by electrical stimulation of the hippocampus or by diisopropylfluorophosphate (DFP) administration. Seizures were assessed by EEG recorded from the hippocampus and cortex.

Results

Flupirtine alone did not terminate ESE within 60 min of administration in any of the three models of ESE. A combination of flupirtine and diazepam terminated ESE within 60 min in all the three models. The drug combination shortened the duration of ESE in all three models. Drug responsiveness was distinct between each model.

Conclusion

A combination of the potassium channel opener flupirtine and diazepam is a potential therapy for ESE.

A retrospective, multicentre study of perampanel given as monotherapy in routine clinical care in people with epilepsy

PURPOSE

Perampanel is approved for adjunctive treatment of focal seizures, with or without secondarily generalised seizures, and for primary generalised tonic-clonic seizures in people with epilepsy aged ≥12 years. Perampanel was recently approved for monotherapy use for partial seizures in the United States. This study provides insight into the feasibility of perampanel monotherapy in real-world settings.

METHODS

This retrospective, non-interventional, multicentre study (NCT02736162) was conducted between January 2013 and March 2016 in specialist epilepsy centres in Europe and Russia. Eligible individuals had a diagnosis of epilepsy and received perampanel primary or secondary monotherapy as routine clinical care. The primary endpoint was proportion of individuals remaining on perampanel monotherapy, after conversion from perampanel adjunctive treatment, at 3, 6, 12, 18 and 24 months (retention rate).

RESULTS

Sixty individuals were in the safety set (female, 63%; white, 97%; aged 18 to <65 years, 73%). Most (85%) received secondary monotherapy with perampanel. At study cut-off, 68% of individuals were continuing on perampanel monotherapy (secondary monotherapy: 55%). The median duration of retention was not calculable due to the high number of individuals ongoing on monotherapy. Twelve individuals had treatment-emergent adverse events that started during perampanel monotherapy, the most frequent was dizziness (5%). One serious treatment-emergent adverse event was reported (pneumonia during adjunctive perampanel treatment).

CONCLUSIONS

In this small retrospective study of individuals who received perampanel monotherapy, the majority maintained monotherapy. Perampanel monotherapy may be an achievable option in some people with epilepsy.

AMPA receptors and perampanel behind selected epilepsies: current evidence and future perspectives

INTRODUCTION

The alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors are the major mediators of glutamate-mediated excitatory neurotransmission, and are critical for synchronization and spread of epileptic activity. Areas covered: AMPA receptor antagonists have been also developed as antiepileptic drugs and perampanel (PER) is the first highly selective, non-competitive AMPA-type glutamate receptor antagonist that is available on the market. It is approved as adjunctive therapy for the treatment of partial-onset seizures with or without secondary generalization, and for primary generalized tonic-clonic seizures in idiopathic generalized epilepsy, in patients aged ≥ 12 years. This article reviews the role of AMPA receptors in the neuronal hyperexcitability underlying epilepsy, the mechanism of action and clinical experience on the anti-seizure activity of PER. Moreover, the rationale for targeting AMPA receptor in specific epileptic disorders, including brain tumor-related epilepsy, mesial temporal lobe epilepsy with/without hippocampal sclerosis, and status epilepticus is evaluated. Finally, the pharmacological rationale for the development of AMPA receptor antagonists in other neurological disorders beyond epilepsy is considered. Expert opinion: Further research aimed at better understanding the pharmacology and blocking mechanism of PER and other AMPA receptor antagonists will drive future development of therapeutic agents that target epilepsy and other neurological diseases.

Effectiveness and tolerability of Perampanel in children, adolescents and young adults with refractory epilepsy: A UK national multicentre study

PURPOSE

Perampanel is one of the latest antiepileptic drugs (AEDs) approved for the treatment of focal and generalised epilepsy in individuals with epilepsy aged 12 years and older. There is sparse data on the use of Perampanel in children under 12. We conducted a study amongst paediatric neurologists in the United Kingdom to investigate its effectiveness and tolerability as an adjunctive therapy in children of all ages with refractory epilepsy.

METHODS

Data was collected via an online questionnaire sent to paediatric neurologists in the UK. Data gathered, prospective in 62 (64.5%) and retrospective in 34 (35.5%) patients, included changes in seizure frequency from baseline and unwanted effects at 3, 6 and 12 months follow-up. Only patients with a minimum follow-up of six months were included.

RESULTS

Ninety six patients (48 females) with refractory epilepsy from 11 of 29 tertiary centres were included. Median [IQR] (range) age was 14 years 11 months [12 years, 16 years 6 months] (11 months-24 years 5 months). Seventy three (76%) had focal epilepsy, sixteen (17%) generalised, and seven (7%) patients both generalised and focal epilepsy. The responder rate, ≥50% seizure reduction from baseline, was 19% for all seizure types at both 6 and 12 months, 19% and 24% for focal seizures, and 25% and 7% for generalised seizures at these time points respectively. The retention rate was 42% at 12 months. Treatment was discontinued due to unwanted effects in 29 (36.7%) of the 79 patients with follow-up data available up to 12 months: 30% due to challenging behaviour, 14% dizziness, and 7.6% somnolence.

CONCLUSION

Perampanel was fairly effective in a heterogeneous group of 96 children and adolescents with very refractory epilepsy. The rate of adverse events leading to discontinuation was considerable in this group.

Enhanced AMPA receptor-mediated neurotransmission on CA1 pyramidal neurons during status epilepticus

Status epilepticus (SE) is a common neurological emergency that results from the failure of the mechanisms responsible for seizure termination or the initiation of mechanisms that lead to abnormally prolonged seizures. Although the failure of inhibitory mechanisms during SE is well understood, the seizure-initiating mechanisms are poorly understood. We tested whether hippocampal α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-mediated transmission was enhanced during SE and assessed the underlying molecular mechanism. In animals in self-sustaining limbic SE the amplitudes of the miniature, spontaneous, and AMPA-evoked excitatory currents recorded from the CA1 pyramidal neurons were larger than those recorded in the controls. The evoked EPSCs rectified inwardly. In these animals, the surface expression of GluA1 subunit-containing AMPARs was increased in the CA1 pyramidal neurons. The phosphorylation of the GluA1 subunit on S831 and S845 residues was reduced in animals in SE. In contrast, the GluA1 subunit surface expression and AMPAR-mediated neurotransmission of dentate granule cells (DGCs) was not altered. Treating animals in SE with the NMDAR antagonist MK-801 or with diazaepam blocked the increased surface expression of the GluA1 subunits. NMDAR blockade also prevented the dephosphorylation of the S845 residue but not that of S831. Targeting NMDARs and AMPARs may provide novel strategies to treat benzodiazepine-refractory SE.

The neuroprotective effect of perampanel in lithium-pilocarpine rat seizure model

PURPOSE

Status epilepticus (SE) causes irreversible neurodegeneration if not terminated quickly. Perampanel (PER), a potent AMPA receptor antagonist, has previously been shown to terminate seizures in the lithium-pilocarpine SE model. In the present study, we assessed whether PER would also prevent neuronal damage in this model.

METHODS

SE was induced in rats using lithium chloride and pilocarpine. Initiation of SE was defined as continuous seizures that exhibited as rearing accompanied by bilateral forelimb clonus (Racine score 4). Either PER (0.6, 2, or 6mg/kg) or diazepam (DZP, 10mg/kg) was administered intravenously 30min after SE initiation. Histopathological samples from treated and seizure-naive rats were taken one week after treatment and then stained with an anti-neuronal nuclei (NeuN) antibody. The sections were analyzed by using a pixel-counting algorithm to quantify the amount of staining in the CA1 subregion of the hippocampus, piriform cortex (Pir), and mediodorsal thalamic nucleus (MD).

RESULTS

DZP administration did not suppress seizures or the degeneration of neurons in the examined areas. Seizures were terminated in 100% of rats treated with 6mg/kg PER (n=8) and in 47% (7/15) of rats treated with 2mg/kg PER, and neurons in the analyzed areas of these animals were preserved to the level seen in naive rats. In the eight animals in which 2mg/kg PER did not terminate the seizures, neuronal loss was partially attenuated in CA1 and Pir, and neurons were fully preserved in MD. Treatment with 0.6mg/kg PER did not terminate the seizures or significantly preserve neurons. The anti-seizure effect of PER correlated well with the degree of neuroprotection in each analyzed area.

CONCLUSIONS

PER exhibited a strong neuroprotective effect in a drug-refractory SE model, and this effect was correlated with its attenuation of seizure.

Current role of perampanel in pediatric epilepsy

Perampanel is among the latest AEDs approved, indicated for the treatment of partial-onset seizures with or without secondary generalization, and for primary generalized tonic-clonic seizures, in patients aged 12 years and older. This paper summarizes the clinical recommendations on the current role of perampanel in the treatment of pediatric epilepsies and future directions for research. The optimal dosage should be comprised between 4 and 12 mg/day, with 8 mg/day being the most common dosage used. The rate and severity of adverse events, including psychiatric symptoms, can be decreased by starting at low doses, and titrating slowly. Overall, perampanel presents an acceptable risk/benefit ratio, but special caution should be made to the risk of seizure aggravation and behavioral problems. The favorable cognitive profile, the ease of use of the titration scheme and the once-daily formulation offer advantage over other AEDs and make this drug particularly suitable for adolescent population. Perampanel is a welcome addition to the armamentarium of the existing AEDs, as it represents a new approach in the management of epilepsy, with a novel mechanism of action and a potential to have a considerable impact on the treatment of adolescents with epilepsy.

AMPA-Kainate Receptor Inhibition Promotes Neurologic Recovery in Premature Rabbits with Intraventricular Hemorrhage

Intraventricular hemorrhage (IVH) in preterm infants leads to cerebral inflammation, reduced myelination of the white matter, and neurological deficits. No therapeutic strategy exists against the IVH-induced white matter injury. AMPA-kainate receptor induced excitotoxicity contributes to oligodendrocyte precursor cell (OPC) damage and hypomyelination in both neonatal and adult models of brain injury. Here, we hypothesized that IVH damages white matter via AMPA receptor activation, and that AMPA-kainate receptor inhibition suppresses inflammation and restores OPC maturation, myelination, and neurologic recovery in preterm newborns with IVH. We tested these hypotheses in a rabbit model of glycerol-induced IVH and evaluated the expression of AMPA receptors in autopsy samples from human preterm infants. GluR1-GluR4 expressions were comparable between preterm humans and rabbits with and without IVH. However, GluR1 and GluR2 levels were significantly lower in the embryonic white matter and germinal matrix relative to the neocortex in both infants with and without IVH. Pharmacological blockade of AMPA-kainate receptors with systemic NBQX, or selective AMPA receptor inhibition by intramuscular perampanel restored myelination and neurologic recovery in rabbits with IVH. NBQX administration also reduced the population of apoptotic OPCs, levels of several cytokines (TNFα, IL-β, IL-6, LIF), and the density of Iba1(+) microglia in pups with IVH. Additionally, NBQX treatment inhibited STAT-3 phosphorylation, but not astrogliosis or transcription factors regulating gliosis. Our data suggest that AMPA-kainate receptor inhibition alleviates OPC loss and IVH-induced inflammation and restores myelination and neurologic recovery in preterm rabbits with IVH. Therapeutic use of FDA-approved perampanel treatment might enhance neurologic outcome in premature infants with IVH.

SIGNIFICANCE STATEMENT

Intraventricular hemorrhage (IVH) is a major complication of prematurity and a large number of survivors with IVH develop cerebral palsy and cognitive deficits. The development of IVH leads to inflammation of the periventricular white matter, apoptosis and arrested maturation of oligodendrocyte precursor cells, and hypomyelination. Here, we show that AMPA-kainate receptor inhibition by NBQX suppresses inflammation, attenuates apoptosis of oligodendrocyte precursor cells, and promotes myelination as well as clinical recovery in preterm rabbits with IVH. Importantly, AMPA-specific inhibition by the FDA-approved perampanel, which unlike NBQX has a low side-effect profile, also enhances myelination and neurological recovery in rabbits with IVH. Hence, the present study highlights the role of AMPA-kainate receptor in IVH-induced white matter injury and identifies a novel strategy of neuroprotection, which might improve the neurological outcome for premature infants with IVH.

Interleukin-1 receptor is a target for adjunctive control of diazepam-refractory status epilepticus in mice

Proinflammatory cytokine interleukin-1 beta (IL-1β) may accumulate in the brain during status epilepticus, but whether it contributes to the progressive refractoriness of SE remains unclear. By using a kainic acid-induced SE mice model, we tested whether pharmacological blockade or knock-out of interleukin-1 receptor type 1 (IL-1R1) could influence the diazepam-refractory phenomenon of prolonged SE. We confirmed diazepam failed to terminate prolonged SE (allowed to continue for 40min before diazepam administration). The expression level of IL-1β in the hippocampus during prolonged SE was significantly higher than that of baseline. Interestingly, prolonged SE was not diazepam-refractory in IL-1R1 knock-out mice. Moreover, administration of interleukin-1 receptor antagonist (IL-1RA) combined with diazepam terminated established prolonged SE, while IL-1RA alone is not capable to terminate prolonged SE. On the contrary, administration of recombinant human IL-1β weakens the efficacy of diazepam by prolonging its latency to terminate non-prolonged SE. Thus, the present study provides direct evidence that accumulated IL-1β contributed to the diazepam refractoriness of prolonged SE, and suggests that interleukin-1 receptor is a target for adjunctive control of diazepam-refractory SE.

Application of a compact magnetic resonance imaging system for toxicologic pathology: evaluation of lithium-pilocarpine-induced rat brain lesions

Magnetic resonance imaging (MRI) is a useful noninvasive tool used to detect lesions in clinical and veterinary medicine. The present study evaluated the suitability of a new easy-to-use compact MRI platform (M2 permanent magnet system, Aspect Imaging, Shoham, Israel) for assisting with preclinical toxicologic pathology examination of lesions in the rat brain. In order to induce brain lesions, male Sprague-Dawley rats were treated once with lithium chloride (127 mg/kg, intraperitoneal [i.p.]) followed by pilocarpine (30 mg/kg, i.p.). One week after dosing, the perfused, fixed brains were collected, analyzed by the MRI system and examined histopathologically. MRI of the brain of treated rats revealed areas of high T1 and middle to low T2 signals, when compared with the controls, in the piriform cortex, lateral thalamic nucleus, posterior paraventricular thalamic nucleus and posterior hypothalamic nucleus of the cerebrum. The altered MRI signal areas were consistent with well-circumscribed foci of neuronal cell degeneration/necrosis accompanied by glial cell proliferation. The present data demonstrated that quick analysis of fixed organs by the MRI system can detect the presence and location of toxicologic lesions and provide useful temporal information for selection of appropriate sections for histopathologic examination before routine slide preparation, especially in complex and functionally heterogeneous organs such as the brain.

Perspectives on treatment options for mesial temporal lobe epilepsy with hippocampal sclerosis

INTRODUCTION

Mesial temporal lobe epilepsy associated with hippocampal sclerosis (MTLE-HS) is a syndrome that is often refractory to drug treatment. The effects on specific syndromes are not currently available from the pre-marketing clinical development of new AEDs; this does not allow the prediction of whether new drugs will be more effective in the treatment of some patients.

AREAS COVERED

We have reviewed all the existing literature relevant to the understanding of a potential effectiveness in MTLE-HS patients for the latest AEDs, namely brivaracetam, eslicarbazepine, lacosamide, perampanel and retigabine also including the most relevant clinical data and a brief description of their pharmacological profile. Records were identified using predefined search criteria using electronic databases (e.g., PubMed, Cochrane Library Database of Systematic Reviews). Primary peer-reviewed articles published up to the 15 June 2015 were included.

EXPERT OPINION

All the drugs considered have the potential to be effective in the treatment of MTLE-HS; in fact, they possess proven efficacy in animal models; currently considered valuable tools for predicting drug efficacy in TLE. Furthermore, for some of these (e.g., lacosamide and eslicarbazepine) data are already available from post-marketing studies while brivaracetam acting on SV2A like levetiracetam might have the same potential effectiveness with the possibility to be more efficacious considering its ability to inhibit voltage gated sodium channels; finally, perampanel and retigabine are very effective drugs in animal models of TLE.

Perampanel in patients with refractory and super-refractory status epilepticus in a neurological intensive care unit

INTRODUCTION

In refractory status epilepticus (SE), because of subcellular maladaptive changes, GABAergic drugs are no longer effective, and the excitatory neurotransmitter glutamate (Glu) plays a major role in seizure perpetuation. Perampanel (PER, licensed since 09/2012) is the first orally active noncompetitive AMPA receptor antagonist for adjunctive treatment of refractory focal epilepsy.

METHODS

We analyzed treatment response, seizure outcome, and adverse effects of add-on treatment with perampanel in patients with refractory status epilepticus in the Neurological Intensive Care Unit (NICU), Salzburg, Austria between 09/2012 and 11/2014 by retrospective chart review.

RESULTS

Twelve patients (75% women) with refractory status epilepticus were treated with PER administered per nasogastric tube between 09/2012 and 11/2014. Median age was 75 years [range: 60-91]. The most frequent SE type was nonconvulsive SE (NCSE) with (5/12, 42%) and without coma (6/12, 50%). In seven patients (58%), SE arose de novo, with an acute symptomatic cause in five patients (42%). Cerebrovascular diseases (4/12, 33%) and cerebral tumors (4/12, 33%) were the most common etiologies. Perampanel was given after a median number of four antiepileptic drugs [range: 2-7] and a median time of 1.5 days [range: 0.8-18.3]. In one patient (8%), clinical improvement was observed within 24h and EEG improvement within 60 h after administration of PER, while in another patient (8%), clinical and EEG improvement was observed more than 48 h after administration. Median initial dose was 4 mg [range: 2-12; SD: 4.11], titrated up to a median of 12 mg [range: 4-12] in steps of 2 to 4 mg per day. No adverse effects were reported regarding cardiorespiratory changes or laboratory parameters. Outcomes after SE were moderate disability in five patients (42%), death in three patients (25%), and persistent vegetative state in two patients (17%).

CONCLUSION

Though glutamate plays a major role in seizure perpetuation, the noncompetitive AMPA receptor antagonist PER could only ameliorate seizure activity in a few patients with refractory SE. The long duration of SE before the administration of PER via nasogastric tube, as well as relatively low doses of PER, might be responsible for the modest result. Perampanel was well tolerated, and no adverse events were reported. This article is part of a Special Issue entitled Status Epilepticus.