Retrospective study of perampanel efficacy and tolerability in myoclonic seizures

Neuraminidase-1 (NEU1): Biological Roles and Therapeutic Relevance in Human Disease

Neuraminidases catalyze the desialylation of cell-surface glycoconjugates and play crucial roles in the development and function of tissues and organs. In both physiological and pathophysiological contexts, neuraminidases mediate diverse biological activities via the catalytic hydrolysis of terminal neuraminic, or sialic acid residues in glycolipid and glycoprotein substrates. The selective modulation of neuraminidase activity constitutes a promising strategy for treating a broad spectrum of human pathologies, including sialidosis and galactosialidosis, neurodegenerative disorders, cancer, cardiovascular diseases, diabetes, and pulmonary disorders. Structurally distinct as a large family of mammalian proteins, neuraminidases (NEU1 through NEU4) possess dissimilar yet overlapping profiles of tissue expression, cellular/subcellular localization, and substrate specificity. NEU1 is well characterized for its lysosomal catabolic functions, with ubiquitous and abundant expression across such tissues as the kidney, pancreas, skeletal muscle, liver, lungs, placenta, and brain. NEU1 also exhibits a broad substrate range on the cell surface, where it plays hitherto underappreciated roles in modulating the structure and function of cellular receptors, providing a basis for it to be a potential drug target in various human diseases. This review seeks to summarize the recent progress in the research on NEU1-associated diseases and highlight the mechanistic implications of NEU1 in disease pathogenesis. An improved understanding of NEU1-associated diseases should help accelerate translational initiatives to develop novel or better therapeutics.

Efficacy and tolerability of perampanel in patients with seizures in real-world clinical practice: A systematic review and meta-analysis

Objectives: The aim of this study was to systematically review the efficacy and tolerability of perampanel (PER) when used as add-on treatment or monotherapy in patients with epilepsy aged 12 years and older in routine clinical practice.

Methods: Electronic and clinical trials databases were searched for observational studies of PER published up to 1 March 2022. The outcomes of interest were responder rates, adverse effects (AEs), and withdrawal rates. Subgroup analyses were performed to explore the potential factors that might affect the efficacy and safety of PER usage.

Results: A total of 56 studies, which included 10,688 patients, were enrolled. The results showed that after 3, 6, and 12 months of PER treatment, the pooled 50% responder rates in patients with epilepsy were 50.0% (95% CI: 0.41–0.60), 44.0% (95% CI: 0.38–0.50), and 39.0% (95% CI: 0.31–0.48), respectively, and the pooled seizure-free rates were 24.0% (95% CI: 0.17–0.32), 21.0% (95% CI: 0.17–0.25), and 20.0% (95% CI: 0.16–0.24), respectively. Subgroup analyses revealed that the efficacy of PER could be affected by the way in which PER is administrated. Patients in the groups where PER was used as the first add-on, primary monotherapy, or combined with non–enzyme-inducing AEDs (non-EIAEDs) displayed a high 50% responder rate and seizure-free rate when compared with those in the late add-on, conversion therapy, or combined with the EIAEDs groups, respectively. Furthermore, the incidences of AEs at 3, 6, and 12 months of PER treatment were 46% (95% CI: 0.38–0.55), 52.0% (95% CI: 0.43–0.60), and 46.0% (95% CI: 0.40–0.52), respectively. The withdrawal rates due to AEs were 8.0% (95% CI: 0.06–0.11), 16.0% (95% CI: 0.13–0.20), and 16% (95% CI: 0.11–0.21) at 3, 6, and 12 months of PER treatment, respectively. Subgroup analyses showed a higher withdrawal rate in the rapid (30%, 95% CI: 0.22–0.38) than in the slow (12%, 95% CI: 0.06–0.18) titration group.

Conclusion: Altogether, PER was effective and could be fairly tolerated in both short-term and long-term usage in patients with epilepsy in routine clinical practice. Furthermore, PER appeared to be more effective when PER was used as the first add-on, monotherapy, or concomitant with non-EIAEDs.

Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022384532.

Replacement of Valproic Acid with New Anti-Seizure Medications in Idiopathic Generalized Epilepsy

Background: Little is known regarding the non-inferiority of new anti-seizure medications (ASMs) in terms of replacing valproic acid (VPA) in patients with idiopathic generalized epilepsy (IGE). We hypothesized that replacement of VPA with new ASMs would offer non-inferior or better control of seizure frequency. The purpose of this study was to compare epileptic seizure frequency between the subset of patients with IGE who were on VPA and the subset of patients with IGE who replaced VPA with new ASMs. Methods: Patients with IGE who were on or had been on VPA between January 2016 and March 2022 were divided into a group that replaced VPA with new ASMs (VPA-replace group) and a group that remained on VPA (VPA-continue group). We then compared the groups in terms of seizure frequency and myoclonus. Results: Of the 606 patients on VPA between January 2016 and March 2022, 156 patients with IGE were enrolled to this study (VPA-replace group, n = 68; VPA-continue group, n = 88). The VPA-replace group included significantly more females than the VPA-continue group (p < 0.001). The VPA-replace group also showed significantly higher seizure frequency before replacement (p < 0.001), but not after replacement (p = 0.074). Patients on monotherapy displayed improved seizure frequency with new ASMs (p < 0.001). Among the new ASMs, perampanel (PER) significantly improved seizure frequency (p = 0.002). Forty-two patients in the VPA-replace group who had myoclonus achieved significant improvements (p < 0.001). Among these, patients on PER monotherapy (p < 0.001) or PER + lamotrigine (0.016) showed significantly improved myoclonus scale scores. Conclusions: This study shows the non-inferiority of new ASMs compared to VPA, with better seizure control using new ASMs in subsets of patients with IGE on monotherapy.

Perampanel for the treatment of patients with myoclonic seizures in clinical practice: Evidence from the PERMIT study

PURPOSE

To investigate the effectiveness, safety and tolerability of perampanel (PER) in treating myoclonic seizures in clinical practice, using data from the PERaMpanel pooled analysIs of effecTiveness and tolerability (PERMIT) study.

METHODS

PERMIT was a pooled analysis of 44 real-world studies from 17 countries, in which patients with focal and generalised epilepsy were treated with PER. This post-hoc analysis included patients with myoclonic seizures at baseline. Retention and effectiveness were assessed after 3, 6, and 12 months; effectiveness was additionally assessed at the last visit (last observation carried forward). Effectiveness assessments included responder rate (≥50% seizure frequency reduction from baseline) and seizure freedom rate (no seizures since at least the prior visit). Safety and tolerability were assessed by evaluating adverse events (AEs) and discontinuation due to AEs.

RESULTS

156 patients had myoclonic seizures (59.0% female; mean age, 32.1 years; idiopathic generalised epilepsy, 89.1%; Juvenile Myoclonic Epilepsy, 63.1%; monthly median myoclonic seizure frequency [interquartile range], 1.7 [1.0-10.0]; mean [standard deviation] prior antiseizure medications, 2.9 [2.6]). Retention was assessed for 133 patients (mean time, 12.1 months), effectiveness for 142, and safety/tolerability for 156. Responder and seizure freedom rates were, respectively, 89.5% and 68.8% at 12 months, and 85.9% and 63.4% at the last visit. Incidence of AEs was 46.8%, the most frequent being dizziness/vertigo (19.2%), irritability (18.6%) and somnolence (9.6%). AEs led to discontinuation of 14.0% of patients over 12 months.

CONCLUSION

PER was associated with reduction in myoclonic seizure frequency in patients with myoclonic seizures treated in everyday clinical practice.

PERMIT study: a global pooled analysis study of the effectiveness and tolerability of perampanel in routine clinical practice

The PERaMpanel pooled analysIs of effecTiveness and tolerability (PERMIT) study was a pooled analysis of data from 44 real-world studies from 17 countries, in which people with epilepsy (PWE; focal and generalized) were treated with perampanel (PER). Retention and effectiveness were assessed after 3, 6, and 12 months, and at the last visit (last observation carried forward). Effectiveness assessments included 50% responder rate (≥ 50% reduction in seizure frequency from baseline) and seizure freedom rate (no seizures since at least the prior visit); in PWE with status epilepticus, response was defined as seizures under control. Safety and tolerability were assessed by evaluating adverse events (AEs) and discontinuation due to AEs. The Full Analysis Set included 5193 PWE. Retention, effectiveness and safety/tolerability were assessed in 4721, 4392 and 4617, respectively. Retention on PER treatment at 3, 6, and 12 months was 90.5%, 79.8%, and 64.2%, respectively. Mean retention time on PER treatment was 10.8 months. The 50% responder rate was 58.3% at 12 months and 50.0% at the last visit, and the corresponding seizure freedom rates were 23.2% and 20.5%, respectively; 52.7% of PWE with status epilepticus responded to PER treatment. Overall, 49.9% of PWE reported AEs and the most frequently reported AEs (≥ 5% of PWE) were dizziness/vertigo (15.2%), somnolence (10.6%), irritability (8.4%), and behavioral disorders (5.4%). At 12 months, 17.6% of PWEs had discontinued due to AEs. PERMIT demonstrated that PER is effective and generally well tolerated when used to treat people with focal and/or generalized epilepsy in everyday clinical practice.

Behavioral adverse events with brivaracetam, levetiracetam, perampanel, and topiramate: A systematic review

PURPOSE

To understand the currently available post-marketing real-world evidence of the incidences of and discontinuations due to the BAEs of irritability, anger, and aggression in people with epilepsy (PWE) treated with the anti-seizure medications (ASMs) brivaracetam (BRV), levetiracetam (LEV), perampanel (PER), and topiramate (TPM), as well as behavioral adverse events (BAEs) in PWE switching from LEV to BRV.

METHODS

A systematic review of published literature using the Cochrane Library, PubMed/MEDLINE, and Embase was performed to identify retrospective and prospective observational studies reporting the incidence of irritability, anger, or aggression with BRV, LEV, PER, or TPM in PWE. The incidences of these BAEs and the rates of discontinuation due to each were categorized by ASM, and where possible, weighted means were calculated but not statistically assessed. Behavioral and psychiatric adverse events in PWE switching from LEV to BRV were summarized descriptively.

RESULTS

A total of 1500 records were identified in the searches. Of these, 44 published articles reporting 42 studies met the study criteria and were included in the data synthesis, 7 studies were identified in the clinical trial database, and 5 studies included PWE switching from LEV to BRV. Studies included a variety of methods, study populations, and definitions of BAEs. While a wide range of results was reported across studies, weighted mean incidences were 5.6% for BRV, 9.9% for LEV, 12.3% for PER, and 3.1% for TPM for irritability; 3.3%* for BRV, 2.5% for LEV, 2.0% for PER, and 0.2%* for TPM for anger; and 2.5% for BRV, 2.6% for LEV, 4.4% for PER, and 0.5%* for TPM for aggression. Weighted mean discontinuation rates were 0.8%* for BRV, 3.4% for LEV, 3.0% for PER, and 2.2% for TPM for irritability and 0.8%* for BRV, 2.4% for LEV, 9.2% for PER, and 1.2%* for TPM for aggression. There were no discontinuations for anger. Switching from LEV to BRV led to improvement in BAEs in 33.3% to 83.0% of patients (weighted mean, 66.6%). *Denotes only 1 study.

CONCLUSIONS

This systematic review characterizes the incidences of irritability, anger, and aggression with BRV, LEV, PER, and TPM, and it provides robust real-world evidence demonstrating that switching from LEV to BRV may improve BAEs. While additional data remain valuable due to differences in methodology (which make comparisons difficult), these results improve understanding of the real-world incidences of discontinuations due to these BAEs in clinical practice and can aid in discussions and treatment decision-making with PWE.

An iPSC-based neural model of sialidosis uncovers glycolytic impairment-causing presynaptic dysfunction and deregulation of Ca2+ dynamics

Sialidosis is a neuropathic lysosomal storage disease caused by a deficiency in the NEU1 gene-encoding lysosomal neuraminidase and characterized by abnormal accumulation of undigested sialyl-oligoconjugates in systemic organs including brain. Although patients exhibit neurological symptoms, the underlying neuropathological mechanism remains unclear. Here, we generated induced pluripotent stem cells (iPSCs) from skin fibroblasts with sialidosis and induced the differentiation into neural progenitor cells (NPCs) and neurons. Sialidosis NPCs and neurons mimicked the disease-like phenotypes including reduced neuraminidase activity, accumulation of sialyl-oligoconjugates and lysosomal expansions. Functional analysis also revealed that sialidosis neurons displayed two distinct abnormalities, defective exocytotic glutamate release and augmented α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptor (AMPAR)-mediated Ca²⁺ influx. These abnormalities were restored by overexpression of the wild-type NEU1 gene, demonstrating causative role of neuraminidase deficiency in functional impairments of disease neurons. Comprehensive proteomics analysis revealed the significant reduction of SNARE proteins and glycolytic enzymes in synaptosomal fraction, with downregulation of ATP production. Bypassing the glycolysis by treatment of pyruvate, which is final metabolite of glycolysis pathway, improved both the synaptsomal ATP production and the exocytotic function. We also found that upregulation of AMPAR and L-type voltage dependent Ca²⁺ channel (VDCC) subunits in disease neurons, with the restoration of AMPAR-mediated Ca²⁺ over-load by treatment of antagonists for the AMPAR and L-type VDCC. Our present study provides new insights into both the neuronal pathophysiology and potential therapeutic strategy for sialidosis.

Exploring the Evidence for Broad-Spectrum Effectiveness of Perampanel: A Systematic Review of Clinical Data in Generalised Seizures

BACKGROUND

The effectiveness of adjunctive perampanel has not been systematically assessed in seizure types other than its approved indications of focal seizures and primary generalised tonic-clonic seizures (PGTCS) in idiopathic generalised epilepsies (IGEs).

OBJECTIVE

We aimed to identify and review available evidence on outcomes with perampanel in generalised seizures and epilepsies to examine its potential as a broad-spectrum anti-seizure medication.

METHODS

Bibliographic databases of publications, clinical trials, and conference abstracts were searched up to August 2020 to identify studies reporting seizure or safety outcomes in patients of any age, with any type of epilepsy-associated generalised seizures treated with perampanel. Data extracted from selected records were tabulated by seizure type and syndrome, and analysed qualitatively (PROSPERO protocol CRD42020201564).

RESULTS

Ninety-one reports met inclusion criteria and were selected: 15 reports of 1 randomised controlled trial (RCT), 8 reports of 4 non-randomised interventional studies, 37 reports of observational studies, 21 case reports and 10 systematic reviews and meta-analyses. Extracted data included 359 patients with PGTCS of any aetiology, 251 with myoclonic seizures, 112 with absence seizures, 50 with tonic seizures and 32 children with epileptic spasms. The most commonly reported epilepsy type was IGE (N = 378) and the most common syndromes were juvenile myoclonic epilepsy (N = 92), progressive myoclonic epilepsies (N = 59) and absence epilepsies (N = 43). The RCT provided Class I evidence of the efficacy and tolerability of adjunctive perampanel for PGTCS in patients aged ≥ 12 years with IGE. Data from other studies provides weaker (observational) evidence of its effectiveness in multiple generalised seizure types, including myoclonic, absence and tonic seizures. There were no patterns suggesting seizure worsening or aggravation in any seizure or epilepsy type.

CONCLUSIONS

The identified studies suggest the potential of perampanel as a broad-spectrum antiseizure medication. Much of the available data, however, come from non-randomised, non-controlled studies and are open to high risk of bias. Further studies are warranted to provide more robust evidence.

Pharmacokinetics, tolerability, and clinical effectiveness of perampanel in Japanese patients with epilepsy

OBJECTIVE

We aimed to evaluate the influence of concomitant antiepileptic drugs (AEDs) on serum perampanel concentration and to correlate the concentration with clinical response and tolerability.

METHODS

A total of 4224 serum samples were obtained from 763 pediatric, adolescent, and adult patients for routine therapeutic drug monitoring. We compared the extent of enzyme induction between cytochrome P450 3A4 (CYP3A4) inducer regimens and built a statistical model to estimate the serum perampanel concentration that considered use of CYP3A4 inducers and inhibitors. To assess the tolerability and clinical effectiveness of perampanel therapy, we used the nested case-control approach. The case group was matched with the control group for age, sex, epilepsy type, and perampanel exposure periods.

RESULTS

Concomitant use of the inducers phenytoin, carbamazepine, and phenobarbital dose-dependently reduced the perampanel concentration by 51 %, 67 %, and 37 %, respectively. The estimate model showed a good correlation between the predicted and measured concentrations (r² = 0.62, p < 0.001). In 206 patients, the seizure reduction from baseline was > 50 % and the median perampanel concentration was 351 ng/mL (interquartile range, 191-603 ng/mL). Adverse events, such as somnolence, dizziness, and irritability, were experienced by 185 patients. The responder odds ratio was 5.1-fold higher in patients with a serum concentration > 600 ng/mL than in those with a serum concentration < 200 ng/mL; however, the former group had a 7.9-fold higher incidence of adverse events.

CONCLUSION

Therapeutic drug monitoring is clinically useful to assess drug interactions between perampanel and CYP3A4 inducers and inhibitors. We recommend that the target concentration of perampanel is initially set at 200-600 ng/mL. Serum concentrations > 600 ng/mL were associated with greater anti-seizure effects but had an increased risk of adverse events.

Efficacy and tolerability of perampanel as a first add-on therapy with different anti-seizure drugs

PURPOSE

To investigate the efficacy and tolerability of perampanel (PER) when administered as a first add-on therapy to patients with focal epilepsy or idiopathic generalized epilepsy (IGE) taking one other antiseizure drug (ASD).

METHODS

This multicentre, retrospective, one-year observational study collected data from patients (≥12 years) who initiated treatment with PER as first add-on therapy. Patients had to be experiencing inadequate seizure control on ASD monotherapy and tried ≤3 ASD monotherapies before initiating PER. Multivariate logistic regression analyses were performed, adjusted for the number and type of previous seizures, duration and aetiology of epilepsy.

RESULTS

Of the 149 patients included in the study (mean age 41 years; 54.4 % male), 118 (79.2 %) were still receiving PER as first add-on treatment after 12 months. Mean PER dose was 6.2 mg/day. At 12 months, 45.6 % were seizure-free and 84.6 % responders. A significant difference in seizure freedom rate was found between patients with IGE and patients with focal epilepsy, but not in responders. Reduced seizure control was observed when PER was administered with strong enzyme-inducing ASDs; conversely, increased seizure control was seen when the same dose of PER was combined with enzyme-inhibiting ASDs. The most frequent adverse events were dizziness (15.4 %), irritability (14.1 %) and drowsiness (14.1 %); no differences in tolerance were observed among different combinations.

CONCLUSION

PER demonstrated a good efficacy and safety profile when used as a first add-on therapy in patients who did not respond to monotherapy. PER dose adjustments may optimize seizure control when combined with strong enzyme-inducing or enzyme-inhibiting ASDs.

Adjunctive perampanel and myoclonic and absence seizures: Post hoc analysis of data from study 332 in patients with idiopathic generalized epilepsy

PURPOSE

This post hoc analysis assessed the effects of adjunctive perampanel on myoclonic and absence seizure outcomes in patients (aged ≥12 years) with idiopathic generalized epilepsy (IGE) and generalized tonic-clonic seizures during the double-blind (up to 8 mg/day) and open-label extension (OLEx; up to 12 mg/day) phases of Study 332.

METHODS

Patients experiencing myoclonic and/or absence seizures during study baseline were included. Assessments for myoclonic and absence seizures included: median percent change in seizure frequency, number of seizure days and seizure-free days (all per 28 days), 50 % and 75 % responder rates, seizure-freedom rates, seizure worsening, and monitoring of treatment-emergent adverse events (TEAEs).

RESULTS

During the double-blind phase, myoclonic and/or absence seizures were reported in 47/163 and 60/163 patients, respectively. Median percent reductions in seizure frequency per 28 days from study baseline were 52.5% and 24.5% (myoclonic seizures) and 7.6 % and 41.2 % (absence seizures) for placebo and perampanel, respectively; seizure-freedom rates were 13.0 % and 16.7 % (myoclonic seizures) and 12.1 % and 22.2 % (absence seizures), respectively. During the OLEx phase, 46/138 and 52/138 patients experienced myoclonic and/or absence seizures, respectively. Responses during the double-blind phase were maintained during long-term (>104 weeks) adjunctive perampanel treatment. The frequency/type of TEAEs was consistent with the known safety profile of perampanel.

CONCLUSION

In this post hoc analysis, adjunctive perampanel was not associated with any overall worsening of absence seizures. Further research is needed to investigate the effect of adjunctive perampanel in IGE patients with myoclonic and/or absence seizures.

Electro-clinical analysis of epilepsy patients with generalized seizures on adjunctive perampanel treatment

Quantifying epileptiform discharges before and after the initiation of treatment can be useful for evaluating the efficacy of antiepileptic drugs in generalized epilepsy. The aim of this study was to determine if the selective α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor antagonist perampanel alters the electroencephalographic signals in patients with drug resistant generalized seizures (primary or secondary). We also assessed the clinical efficacy, safety and tolerability of perampanel as an adjunctive treatment for patients with refractory generalized seizures after 3, 6 and 12 months of treatment to determine if there is an electro-clinical correlation. We carried out a 1-year retrospective, unicentric, observational, descriptive and non-interventional study to analyze changes in epileptiform discharges, seizure frequency and adverse effects in patients with generalized seizures taking perampanel as an add-on treatment. Perampanel significantly reduced the total number, total duration, maximal duration and average duration of epileptiform discharges in patients with primary generalized epilepsy (n = 44). In patients with focal onset epilepsy and secondary generalized seizures (n = 8) significant decreases in the maximal duration and average duration of epileptiform discharges were found. These findings correlate with the significant decrease in seizure frequency and clinical improvement observed after taking perampanel as an adjunctive therapy for 3, 6 and 12 months. To our knowledge, this is the first study to show that perampanel reduces epileptiform activity, and that this effect correlates with patients' clinical improvement. Analysing patients' electroencephalographic activity in response to perampanel could be useful for assessing the drug's efficacy and optimising adjunctive treatments.

Perampanel for nonepileptic myoclonus in Angelman syndrome

BACKGROUND

Angelman syndrome (AS) is a neurodegenerative disorder caused by functional loss of the maternal ubiquitin-protein ligase 3A gene. Nonepileptic myoclonus, also described as tremulous movement, often occurs during puberty and increases in adulthood. The involuntary movement in AS has not been defined patho-physiologically and the drugs used such as levetiracetam and piracetam are not always effective. Recently, the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor antagonist, perampanel (PER), was used to alleviate myoclonus in progressive myoclonus epilepsy. Herein, we tested the efficacy of PER for nonepileptic myoclonus.

METHODS AND RESULTS

Four patients with AS, aged from 20 to 40 years at the beginning of treatment, were enrolled in our study. All patients reported disruption to their daily lives from the myoclonus movement. They experienced mild to moderate improvement with the starting dose of 2 mg. The dose was increased to 4 mg in one patient to achieve sufficient efficacy, while two had their dose reduced to 1 mg due to dizziness or possible exacerbation of myoclonus. The last patient continued to take the starting dose. Follow-up over 16-20 months revealed a significant reduction in the severity of nonepileptic myoclonus in all patients.

CONCLUSION

Our study suggests that PER could be one of the promising drugs for nonepileptic myoclonus in AS.

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.

An Italian multicentre study of perampanel in progressive myoclonus epilepsies

Perampanel (PER) is a novel anti-seizure medication useful in different types of epilepsy. We intended to assess the effectiveness of PER on cortical myoclonus and seizure frequency in patients with progressive myoclonus epilepsy (PME), using quantitative validated scales. Forty-nine patients aged 36.6 ± 15.6 years with PME of various aetiology (18 EPM1, 12 EPM2, five with sialidosis, one with Kufs disease, one with EPM7, and 12 undetermined) were enrolled between January 2017 and June 2018. PER at the dose of 2-12 mg (5.3 ± 2.5) was added to existing therapy. Myoclonus severity was assessed using a minimal myoclonus scale (MMS) in all the patients before and after 4-6 months of steady PER dose, and by means of the Unified Myoclonus Rating Scale (UMRS) in 20 patients. Logistic regression analysis was used to identify the factors potentially predicting treatment efficacy. Four patients dropped out in the first two months due to psychiatric side effects. In the remaining patients, PER reduced myoclonus severity as assessed using MMS (Wilcoxon test: p < 0.001) and UMRS (p < 0.001), with the 'Action myoclonus' section of the UMRS showing the greatest improvement. The patients with EPM1 or EPM1-like phenotype were more likely to improve with PER (p = 0.011). Convulsive seizures which have recurred at least monthly in 17 patients were reduced by >50%. Side effects occurred in 22/49 (44.8%) patients, the most common being irritability followed by drowsiness. PER is effective in treating myoclonus and seizures in PME patients. The frequency of psychiatric side effects suggests the need for careful patient monitoring.

Low-dose perampanel improves refractory cortical myoclonus by the dispersed and suppressed paroxysmal depolarization shifts in the sensorimotor cortex

OBJECTIVE

To elucidate the effects of perampanel (PER) on refractory cortical myoclonus for dose, etiology and somatosensory-evoked potential (SEP) findings.

METHODS

We examined 18 epilepsy patients with seizure and cortical myoclonus. Based on data accumulated before and after PER treatment, correlations among clinical scores in myoclonus and activities of daily life (ADL); early cortical components of SEP; and PER blood concentration, were analyzed.

RESULTS

PER (mean dose: 3.2 ± 2.1 mg/day) significantly improved seizures, myoclonus and ADL and significantly decreased the amplitude of and prolonged latency of giant SEP components. The degree of P25 and N33 prolongations (23.8 ± 1.6 to 24.7 ± 1.7 ms and 32.1 ± 4.0 to 33.7 ± 3.4 ms) were significantly correlated with improved ADL score (p = 0.019 and p = 0.025) and blood PER concentration (p = 0.011 and p = 0.025), respectively.

CONCLUSIONS

Low-dose PER markedly improved myoclonus and ADL in patients with refractory cortical myoclonus. Our results suggest that SEP, particularly P25 latency, can be used as a potential biomarker for assessing the objective effects of PER on intractable cortical myoclonus.

SIGNIFICANCE

In this study, PER lessened the degree of synchronized discharges in the postsynaptic neurons in the primary motor cortex.

Efficacy and tolerability of perampanel in pediatric patients with Dravet syndrome

PURPOSE

In the present study, we aimed to investigate the efficacy and tolerability of perampanel in patients with Dravet syndrome.

METHODS

We retrospectively reviewed data regarding seizure frequency and adverse effects in 10 patients (four boys, six girls) with Dravet syndrome following treatment with perampanel. Perampanel treatment was considered effective when seizure frequency had been reduced by more than 50%.

RESULTS

The mean age of patients at perampanel introduction was 11.5 ± 2.2 years. Seizure types were as follows: generalized tonic-clonic seizure (n = 8), unilateral clonic seizure (n = 6), myoclonic seizure (n = 3), atypical absence seizure (n = 3), and focal impaired awareness seizure (n = 1). The average number of concomitant anti-epileptic drugs (AEDs) was 3 ± 0.9. The mean duration of perampanel use was 11.1 ± 3.8 months. Seizure frequency was reduced by more than 50% in five patients (50%). The efficacy of perampanel for each seizure type was as follows: generalized tonic-clonic seizure: 50% (4/8), unilateral clonic seizure: 50% (3/6), myoclonic seizure: 33% (1/3), atypical absence seizure: 33% (1/3), and focal impaired awareness seizure: 100% (1/1). The effects of perampanel in each patient occurred between 3 and 6 months following the initiation of treatment. Seizure reduction was observed beginning at perampanel doses of 0.1 ± 0.07 mg/kg/day. Adverse events were observed in seven of 10 patients. Although somnolence was noted in 50% of patients, most events were mild.

CONCLUSIONS

The results of this retrospective observational study indicate that perampanel treatment may be promising in some patients with Dravet syndrome. Additional studies are necessary to verify the actual efficacy of perampanel for Dravet syndrome.

An Update on Myoclonus Management

INTRODUCTION

Myoclonus is a hyperkinetic movement disorder characterized by sudden, brief, lightning-like involuntary jerks. There are many possible causes of myoclonus and both the etiology and characteristics of the myoclonus are important in securing the diagnosis and treatment. Myoclonus may be challenging to treat, as it frequently requires multiple medications for acceptable results. Few randomized controlled trials investigating the optimal treatment for myoclonus are available, and expert experience and case series guide treatment. Areas Covered: In this article, the authors review the basics of myoclonus and its classification. The authors discuss the current management of myoclonus and then focus on recent updates in the literature, including both pharmacologic and surgical options. Expert opinion: Myoclonus remains a challenge to manage, and there is a paucity of rigorous clinical trials guiding treatment paradigms. Furthermore, due to the etiological heterogeneity of myoclonus, defining the appropriate scope for high-quality clinical trials is challenging. In order to advance the field, the myoclonus study group needs to be revived in the US and abroad so that interested investigators can collaborate on multicenter clinical trials for myoclonus treatments.

Pharmacokinetic and pharmacodynamic considerations for the clinical efficacy of perampanel in focal onset seizures

INTRODUCTION

Medical therapy is the mainstay of management of epilepsy. Despite the increasing number of available antiepileptic drugs (AEDs), approximately one-third of epileptic patients do not have adequate control of seizures. There is still a need for the development of new AEDs with enhanced effectiveness and tolerability. Areas covered: The present manuscript is based on an Internet and PubMed search (January 2005 to August 2018). It is focused on pharmacokinetic and clinical data of perampanel (PER) for the treatment of epilepsy. Expert opinion: PER has a novel mechanism of action, which opens up new options for a rational combination therapy. Phase III trials have demonstrated the efficacy and safety of PER as adjunctive therapy for the treatment of partial-onset seizures (POS) and primary generalized tonic-clonic seizures in patients aged ≥12 years. PER is also approved by FDA as monotherapy for the treatment of POS. A clinical trial is ongoing to verify the efficacy and safety of PER monotherapy in untreated patients with POS. In the future, head-to-head comparisons are needed to determine the exact position of PER relative to other AEDs. Moreover, further studies are needed to evaluate the efficacy and safety of PER in patients aged <12 years.

ABBREVIATIONS

4βOHC: 4β-hydroxycholesterol; AUC: area under the curve; CBZ: Carbamazepine; CLCr: creatinine clearance; Cmax: maximum plasma concentration; CYP: cytochrome P; EIAED: enzyme-inducing antiepileptic drug; EMA: European Medicines Agency; FDA: Food and Drug Administration; GI: gastrointestinal; OXC: oxcarbazepine; PER: perampanel; PGTC: primary generalized tonic-clonic; PHT: phenytoin; POS: partial-onset seizures; QD: once-daily; TEAE: treatment-emergent adverse event; Tmax: median time to reach peak concentration; UGT: uridine diphosphoglucose-glucuronosyltransferase; VPA: valproic acid.

Perampanel in routine clinical use in idiopathic generalized epilepsy: The 12-month GENERAL study

OBJECTIVE

To analyze the effectiveness and tolerability of perampanel across different seizure types in routine clinical care of patients with idiopathic generalized epilepsy (IGE).

METHODS

This multicenter, retrospective, 1-year observational study collected data from patient records at 21 specialist epilepsy units in Spain. All patients who were aged ≥12 years, prescribed perampanel before December 2016, and had a confirmed diagnosis of IGE were included.

RESULTS

The population comprised 149 patients with IGE (60 with juvenile myoclonic epilepsy, 51 generalized tonic-clonic seizures [GTCS] only, 21 juvenile absence epilepsy, 10 childhood absence epilepsy, 6 adulthood absence epilepsy, and one Jeavons syndrome). Mean age was 36 years. The retention rate at 12 months was 83% (124/149), and 4 mg was the most common dose. At 12 months, the seizure-free rate was 59% for all seizures (88/149); 63% for GTCS (72/115), 65% for myoclonic seizures (31/48), and 51% for absence seizures (24/47). Seizure frequency was reduced significantly at 12 months relative to baseline for GTCS (78%), myoclonic (65%), and absence seizures (48%). Increase from baseline seizure frequency was seen in 5.2% of patients with GTCS seizures, 6.3% with myoclonic, and 4.3% with absence seizures. Perampanel was effective regardless of epilepsy syndrome, concomitant antiepileptic drugs (AEDs), and prior AEDs, but retention and seizure freedom were significantly higher when used as early add-on (after ≤2 prior AEDs) than late (≥3 prior AEDs). Adverse events were reported in 50% of patients over 12 months, mostly mild or moderate, and irritability (23%), somnolence (15%), and dizziness (14%) were most frequent.

SIGNIFICANCE

In routine clinical care of patients with IGE, perampanel improved seizure outcomes for GTCS, myoclonic seizures, and absence seizures, with few discontinuations due to adverse events. This is the first real-world evidence with perampanel across different seizure types in IGE.