Perampanel, a selective, noncompetitive α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor antagonist, as adjunctive therapy for refractory partial-onset seizures: interim results from phase III, extension study 307

Perampanel, an antagonist of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors, for the treatment of epilepsy: studies in human epileptic brain and nonepileptic brain and in rodent models

Perampanel [Fycompa, 2-(2-oxo-1-phenyl-5-pyridin-2-yl-1,2-dihydropyridin-3-yl)benzonitrile hydrate 4:3; Eisai Inc., Woodcliff Lake, NJ] is an AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor antagonist used as an adjunctive treatment of partial-onset seizures. We asked whether perampanel has AMPA receptor antagonist activity in both the cerebral cortex and hippocampus associated with antiepileptic efficacy and also in the cerebellum associated with motor side effects in rodent and human brains. We also asked whether epileptic or nonepileptic human cortex is similarly responsive to AMPA receptor antagonism by perampanel. In rodent models, perampanel decreased epileptic-like activity in multiple seizure models. However, doses of perampanel that had anticonvulsant effects were within the same range as those engendering motor side effects. Perampanel inhibited native rat and human AMPA receptors from the hippocampus as well as the cerebellum that were reconstituted into Xenopus oocytes. In addition, with the same technique, we found that perampanel inhibited AMPA receptors from hippocampal tissue that had been removed from a patient who underwent surgical resection for refractory epilepsy. Perampanel inhibited AMPA receptor-mediated ion currents from all the tissues investigated with similar potency (IC50 values ranging from 2.6 to 7.0 μM). Cortical slices from the left temporal lobe derived from the same patient were studied in a 60-microelectrode array. Large field potentials were evoked on at least 45 channels of the array, and 10 μM perampanel decreased their amplitude and firing rate. Perampanel also produced a 33% reduction in the branching parameter, demonstrating the effects of perampanel at the network level. These data suggest that perampanel blocks AMPA receptors globally across the brain to account for both its antiepileptic and side-effect profile in rodents and epileptic patients.

Long-term safety of perampanel and seizure outcomes in refractory partial-onset seizures and secondarily generalized seizures: results from phase III extension study 307

OBJECTIVE

To evaluate safety, tolerability, seizure frequency, and regional variations in treatment responses with the AMPA antagonist, perampanel, in a large extension study during up to 3 years of treatment.

METHODS

Patients ≥ 12 years old with partial-onset seizures despite treatment with 1-3 antiepileptic drugs at baseline completed a perampanel phase III trial and entered extension study 307 (NCT00735397). Patients were titrated to 12 mg/day (or their individual maximum tolerated dose) during the blinded conversion period, followed by open-label maintenance. Exposure, safety (adverse events [AEs], vital signs, weight, electrocardiography [ECG], laboratory values) and seizure outcomes were analyzed; key measures were assessed by geographic regions.

RESULTS

Among 1,216 patients, median exposure was 1.5 years (range 1 week to 3.3 years), with >300 patients treated for >2 years. Treatment retention was 58.5% at cutoff. AEs reported in ≥ 10% of patients were dizziness, somnolence, headache, fatigue, irritability, and weight increase. Only dizziness and irritability caused discontinuation in >1% of patients (3.9% and 1.3%, respectively). The only serious AEs reported in >1% of patients were epilepsy-related (convulsion, 3.0%; status epilepticus, 1.1%). No clinically relevant changes in vital signs, ECG or laboratory parameters were seen. After titration/conversion, responder rate and median percentage change from baseline in seizure frequency were stable: 46% for both measures at 9 months (in 980 patients with ≥ 9 months' exposure) and 58% and 60%, respectively, at 2 years (in the 337 patients with 2 years' exposure). Median percentage reduction in frequency of secondarily generalized (SG) seizures ranged from 77% at 9 months (N = 422) to 90% at 2 years (N = 141). Among the 694 patients with maintenance data ≥ 1 year, 5.3% were seizure-free for the entire year.

SIGNIFICANCE

No new safety signals emerged during up to 3 years of perampanel exposure in 39 countries. Seizure responses remained stable, with marked reductions, particularly in SG seizures.

Pharmacotherapy of focal epilepsy

INTRODUCTION

Epilepsy is the most common neurological condition worldwide with significant psychosocial and physical morbidity. Its management requires expertise and good pharmacological knowledge of the available options.

AREAS COVERED

This review covers the management of focal epilepsy addressing the common questions arising through the patients' journey, including timing of starting initial treatment, monotherapy options, add-on treatment for refractory cases and withdrawal of medication during remission.

EXPERT OPINION

Initiating anti-epileptic drug (AED) treatment requires assessment of patient preferences and of evidence of benefit and harm. Evidence of benefit will come primarily from randomised controlled trials, although in epilepsy, most trials are undertaken to inform regulatory decision and have important limitations for informing clinical decisions. Evidence about harm may come not only from randomised trials but also from other sources. Most patients will start treatment following a second focal seizure. Carbamazepine and lamotrigine are good initial monotherapy options. Newer AEDs have proof of efficacy as monotherapy but evidence is insufficient to recommend them as first-line treatments. For refractory cases, there are an increasing number of AEDs available, but evidence of efficacy is primarily from placebo-controlled trials, and there is no robust evidence to inform a choice among treatments.

Network meta-analyses of antiepileptic drug efficacy and tolerability in drug-resistant focal epilepsies: a clinical perspective

PURPOSE

Network meta-analysis (NMA) is a new technique that allows multiple treatment comparisons and provides estimates of effect sizes for all possible pair-wise comparisons. Several NMAs of antiepileptic drug (AED) efficacy and tolerability in individuals with refractory focal epilepsy, however, came to non-specific and, in some cases, divergent conclusions. We review some clinical factors that may be responsible for these inconsistent findings.

RESULTS

A major issue is the small number of individuals included in the meta-analyses with consequent wide confidence intervals and lack of ability to achieve significant results. Further issues are lack of robustness of the measured efficacy outcome-the responder ratio (the percentage of individuals with a >50 % improvement in seizure frequency); the selection of randomized studies (RCTs) included, i.e., the inclusion of studies with heterogeneous populations (children and adults); and inclusion of people treated with different doses of the experimental drug. Some methods of analysing data from RCTs, such as the last observation carried forward (LOCF) analysis, the choice of different phases of the study to compare to baseline, and the year in which the trial was conducted, selectively affect measurement of efficacy outcomes. Titration speed and other methodological aspects selectively affect tolerability.

CONCLUSION

Several factors restrict the analysis of clinically useful estimates of the comparative efficacy of AEDs, while analysis of tolerability may be easier to accomplish.

A multicenter survey of clinical experiences with perampanel in real life in Germany and Austria

Perampanel (PER) has been approved by the European Medicines Agency (EMA) for adjunctive treatment of patients with partial-onset seizures from age 12 years on. It has been introduced to the market in Germany and Austria in 2012. This cross-sectional observational study summarizes the clinical experience of nine centers with adjunctive PER. Patients were consecutively followed from the initiation of PER on. Only patients with a minimum observational period of six months (in case of ongoing treatment) were recruited. Efficacy data reflect the preceding three months at last observation, tolerability data were assessed at the last observation carried forward. 281 patients were included. After six months 169 were still on PER so that a retention rate of 60% resulted. 43 patients were seizure-free for the preceding 3 months (15%). Overall incidence of adverse events was 52.0%. The leading adverse events were somnolence (24.6%) and dizziness (19.6%) followed by ataxia (3.9%), aggression (2.8%), nausea (2.5%) and irritability (2.1%). We conclude that adjunctive PER may lead to at least temporary freedom of seizures in some of these highly difficult-to-treat patients. Adverse events are not uncommon.

Perampanel for adjunctive treatment of partial-onset seizures: a pooled dose-response analysis of phase III studies

OBJECTIVE

To better understand the relationship between efficacy and perampanel dose, integrated actual (last) dose data from three phase III trials and an extension study (blinded Conversion Period; open-label Maintenance Period) were analyzed.

METHODS

Seizure frequency data were analyzed in patients who were randomized to and completed the 13-week Maintenance Period of the phase III studies on perampanel 8 mg, and who received an actual (last) dose of 12 mg during (1) the extension 16-week blinded Conversion Period or (2) weeks 1-13 of the extension Maintenance Period. Due to a treatment-by-region interaction (p = 0.042), analyses excluded patients from the Latin America region (n = 162/1,480; 10.9% of the treated cohort).

RESULTS

Of 372 patients randomized to 8 mg in the phase III studies, 273 completed the Maintenance Period at 8 mg and 267 entered the extension study. In patients who then had an actual (last) dose of 12 mg during the extension blinded Conversion Period (n = 217), median percent change in seizure frequency per 28 days improved from -32.4% (8 mg, phase III Maintenance Period) to -44.2% (12 mg, extension blinded Conversion Period); 50% responder rates increased slightly from 37.3% to 42.9%. In patients who completed the phase III studies on 8 mg and had an actual (last) dose of 12 mg during weeks 1-13 of the extension Maintenance Period (n = 181), median percent change in seizure frequency per 28 days improved from -34.1% (phase III Maintenance Period) to -46.0% (weeks 1-13 extension Maintenance Period); 50% responder rates were 39.2% and 46.4%. Seizure control remained substantially unchanged in patients who completed the phase III studies at 12 mg and continued on that dose during the extension.

SIGNIFICANCE

Increasing perampanel dose from 8 to 12 mg can produce additional benefits in seizure control in at least some patients who tolerate the higher dose.

Efficacy of perampanel: a review of pooled data

Perampanel (PER) has been tested in three randomized placebo-controlled prospective phase III trials as an adjunctive antiepileptic drug (AED) in adult and adolescent patients age 12 years and older who had ongoing focal epileptic seizures despite receiving one to three AEDs. Patients were randomized to once-daily placebo or maintenance dosages of 2, 4, or 8 mg of PER daily in one trial or to dosages of 8 and 12 mg of PER in the other two studies. Baseline and double-blind titration periods comprised 6 weeks each before a 12-week maintenance phase. Primary endpoints were median change in partial seizure frequency (baseline vs. double-blind phase), and the percentage of patients achieving >50% reduction in seizure frequency (so-called responders, baseline vs. maintenance). All patients had the opportunity to enter an open follow-up study that allowed a titration of PER of up to 12 mg. Pooled data of all three studies included 1,478 patients. There was a statistically significant median change in seizure frequency and responder rates with PER dosages of 4, 8, and 12 mg (p < 0.01, each dose vs. placebo). Both the results of each trial and the pooled data are reported in this review. For the open follow-up study, 1,218 patients were recruited. Ninety-one percent finally reached maintenance dosages of 10 or 12 mg. After 1 year, both median seizure reduction and responder rates reached almost 50%.

Adverse effects and safety profile of perampanel: a review of pooled data

Quality of life is directly related to the number and severity of adverse effects, and a successful antiepileptic medication must demonstrate a good balance between efficacy and tolerability. Perampanel is a newly licensed antiepileptic medication for the adjunctive treatment of patients (age 12 and older) with partial epilepsy with or without secondary generalization. Safety endpoints in the three phase III trials (304, 305, and 306) included treatment-emergent adverse events (TEAEs), vital signs, clinical laboratory parameters, and electrocardiography studies (ECGs). The most common adverse drug reactions in patients receiving perampanel were dizziness, somnolence, fatigue, irritability, nausea, and falls. Of particular concern to patients are cognitive and psychiatric side effects. Overall, depression and aggression were reported more frequently in patients taking perampanel, particularly at higher doses, than in patients taking placebo. TEAEs necessitated the withdrawal of perampanel in 99 patients (9.5%) and placebo in 21 patients (4.8%). Typically this was due to dizziness, convulsion, and somnolence. There were no clinically important changes or treatment group differences in vital signs, ECG measures, or biochemical or hematologic parameters. Weight increase of greater than 7% was seen in 14.6% of perampanel-treated patients versus 7.1% of placebo-treated patients. Overall, perampanel appears to be associated with a relatively low incidence of serious adverse effects, particularly at low doses, and the majority of TEAEs were mild or moderate in intensity. The incidence of predictable side effects, such as somnolence and dizziness, is seen more frequently at higher doses. Of importance is the greater rate of psychiatric side effects in patients treated with perampanel, principally, irritability and aggression, than with placebo. However, the rate of serious psychiatric TEAEs was low.

Two-year seizure reduction in adults with medically intractable partial onset epilepsy treated with responsive neurostimulation: final results of the RNS System Pivotal trial

OBJECTIVE

To demonstrate the safety and effectiveness of responsive stimulation at the seizure focus as an adjunctive therapy to reduce the frequency of seizures in adults with medically intractable partial onset seizures arising from one or two seizure foci.

METHODS

Randomized multicenter double-blinded controlled trial of responsive focal cortical stimulation (RNS System). Subjects with medically intractable partial onset seizures from one or two foci were implanted, and 1 month postimplant were randomized 1:1 to active or sham stimulation. After the fifth postimplant month, all subjects received responsive stimulation in an open label period (OLP) to complete 2 years of postimplant follow-up.

RESULTS

All 191 subjects were randomized. The percent change in seizures at the end of the blinded period was -37.9% in the active and -17.3% in the sham stimulation group (p = 0.012, Generalized Estimating Equations). The median percent reduction in seizures in the OLP was 44% at 1 year and 53% at 2 years, which represents a progressive and significant improvement with time (p < 0.0001). The serious adverse event rate was not different between subjects receiving active and sham stimulation. Adverse events were consistent with the known risks of an implanted medical device, seizures, and of other epilepsy treatments. There were no adverse effects on neuropsychological function or mood.

SIGNIFICANCE

Responsive stimulation to the seizure focus reduced the frequency of partial-onset seizures acutely, showed improving seizure reduction over time, was well tolerated, and was acceptably safe. The RNS System provides an additional treatment option for patients with medically intractable partial-onset seizures.

Perspective on the use of perampanel and intravenous carbamazepine for generalized seizures

INTRODUCTION

Several antiepileptic drugs are available for the treatment of epileptic patients. However, the treatment of some seizure types and novel drug formulations deserve further advances in epilepsy research.

AREAS COVERED

The authors analyze the published evidence on the efficacy of perampanel against secondarily generalized seizures (SGS) and report the currently available development of intravenous (IV) formulations of carbamazepine (CBZ), commenting on their potential in the clinical setting.

EXPERT OPINION

Perampanel is the first noncompetitive AMPA receptor antagonist to be approved as adjunctive treatment in patients with partial-onset (focal) seizures (POS) with or without secondary generalization. Apart from its efficacy and safety on POS, a consistent body of evidence supports its efficacy in SGS at a minimum dose of 8 mg/day; however, such dose appears close to the best-tolerated dose. CBZ is a poorly water-soluble compound; many efforts to develop a parenteral formulation have not been successful so far. Novel IV CBZ formulations seem to exhibit favorable pharmacokinetics along with good tolerability in animal models and in patients taking oral CBZ. Further studies are needed to assess whether larger doses will be as well tolerated, allowing IV CBZ to be used as bridge therapy when the oral route is not feasible or in patients naïve to CBZ.

Perampanel

Each month, subscribers to The Formulary Monograph Service receive 5 to 6 well-documented monographs on drugs that are newly released or are in late phase 3 trials. The monographs are targeted to Pharmacy & Therapeutics Committees. Subscribers also receive monthly 1-page summary monographs on agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation/medication use evaluation (DUE/MUE) is also provided each month. With a subscription, the monographs are sent in print and are also available on-line. Monographs can be customized to meet the needs of a facility. A drug class review is now published monthly with The Formulary Monograph Service. Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. For more information about The Formulary Monograph Service.Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. For more information about The Formulary Monograph Service, call The Formulary at 800-322-4349. The April 2013 monograph topics are alogliptin, crofelemer, lomitapide, ponatinib, and sumatriptan iontophoretic transdermal. The DUE/MUE is on alogliptin.

AMPA receptor inhibitors for the treatment of epilepsy: the role of perampanel

α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors in the postsynaptic membrane are involved in fast excitatory signaling in the brain and their activation may lead to the firing of action potentials. Talampanel and perampanel were the first noncompetitive AMPA receptor antagonists to be tested as add-on drugs in patients with refractory partial seizures, and were found to be effective in improving seizure control. Due to an unfavorable kinetic and tolerability profile, talampanel clinical development in the field of epilepsy was discontinued early while perampanel has been recently approved in Europe and the USA as adjunctive therapy for adults with partial seizures with or without secondary generalization. The recommended perampanel starting dose is 2 mg/day once daily, which can be increased up to the recommended maintenance dose of 4-8 mg/day. Increments should be of 2 mg/day and based on clinical response and tolerability. Titration should be performed at 1-week intervals or at lower speed and a 12-mg daily dose should be considered after careful evaluation. To date, no serious and/or idiosyncratic adverse effects have been associated with this agent. Most frequently reported adverse effects are dizziness, ataxia, aggression, irritability, vertigo, somnolence, fatigue, headache and gait disturbance. Weight increase is the only non-neurological adverse effects associated with perampanel.

Perampanel: a selective AMPA antagonist for treating seizures

Perampanel is a selective, noncompetitive AMPA receptor antagonist that has recently been approved for treating localization-related epilepsy. This article reviews the pharmacology, clinical development, efficacy, and safety/tolerability of perampanel.

in Silico investigation of the structural requirements for the AMPA receptor antagonism by quinoxaline derivatives

Glutamate receptors have been implicated in various neurological disorders and their antagonism offers a suitable approach for the treatment of such disorders. The field of drug design and discovery aims to find best medicines to prevent, treat and cure diseases quickly and efficiently. In this regard, computational tools have helped medicinal chemists modify and optimize molecules to potent drug candidates with better pharmacokinetic profiles, and guiding biologists and pharmacologists to explore new disease genes as well as novel drug targets. In the present study, to understand the structural requirements for AMPA receptor antagonism, molecular docking study was performed on 41 structurally diverse antagonists based on quinoxaline nucleus. Lamarckian genetic algorithm methodology was employed for docking simulations using AutoDock 4.2 program. The results obtained signify that the molecular docking approach is reliable and produces a good correlation coefficient (r² = 0.6) between experimental and docking predicted AMPA receptor antagonistic activity. The aromatic moiety of quinoxaline core has been proved to be vital for hydrophobic contacts exhibiting - interactions in docked conformations. However, polar moieties such as carboxylic group and 1,2,4-triazole moieties were noted to be sites for hydrophilic interactions in terms of hydrogen bonding with the receptor. These analyses can be exploited to design and develop novel AMPA receptor antagonists for the treatment of different neurological disorders.

A review on antiepileptic drugs-dependent fatigue: pathophysiological mechanisms and incidence

Fatigue represents a common side effect of several drugs, however, the underlying mechanisms have not been well identified. A depression of the central nervous system (CNS) and/or changes in peripheral processes have been associated with the development of fatigue. Antiepileptic drugs (AEDs), generally decreasing CNS excitability, are used in the treatment of seizures as well as other neurological and psychiatric diseases. Fatigue is certainly a common AEDs' side effect, although a high degree of variability exists depending on both patients' characteristics and the drug used. Here, we delineate the pathophysiological central and peripheral mechanisms by which AEDs may cause fatigue also reviewing the available clinical data in order to assess a possible AEDs rank and highlight each AEDs related risk. It appears that drugs acting on the GABAergic system have the highest incidence (with tiagabine exception) of fatigue followed by Gabapentin and Levetiracetam whereas drugs mainly inhibiting sodium channels (Carbamazepine, Eslicarbazepine, Lamotrigine, Phenytoin and Valproate) have the lowest. However, the dose used, AEDs related side effects and patients' characteristics might influence the degree of fatigue observed.

Efficacy of perampanel: a review of clinical trial data

The efficacy of adjunctive perampanel has been investigated in an extensive clinical development program across a broad, multinational population of patients with refractory partial-onset seizures. Further to the results of two Phase II dose-finding studies, perampanel was evaluated in three large Phase III registration studies at the predicted no-effect dose of 2 mg/day and the predicted effective doses of 4, 8, and 12 mg/day. In all three studies, perampanel 4, 8, and 12 mg/day consistently provided significant reductions in the frequency of partial-onset seizures compared with placebo. Improvements in responder rates and seizure freedom rates were also observed. In addition, data from recent interim analyses of extension studies have indicated that these efficacy outcomes may be maintained with long-term treatment. Overall, these studies form a solid evidence base to support the efficacy of adjunctive perampanel in the treatment of refractory partial-onset seizures.

Perampanel: What is its Place in the Management of Partial Onset Epilepsy?

Introduction

Current pathways for treatment of partial onset epilepsy are diverse and include 14 new antiepileptic drugs (AEDs) licensed for use as either monotherapy or adjunctive therapy. However, the impact of these new AEDs on the treatment of partial epilepsy has so far been disappointing and there persists a need for additional drugs. Recently, perampanel, a first-in-class AED was licensed as an adjunct for the management of refractory partial onset seizures with or without secondary generalization in patients 12 years and older. This review highlights the current management of partial epilepsy and analyses the published clinical and preclinical data of perampanel to consider its potential role in the treatment of partial epilepsy.

Methods

A literature review of Embase, Medline and PubMed was conducted in April 2013 using the search terms ‘perampanel’ and ‘AMPA receptor antagonist/blocker’. Publications were included if they discussed perampanel in the context of preclinical or clinical epilepsy.

Results

Perampanel acts on the glutamate pathway. It is a novel highly selective non-competitive alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist. This is a previously untargeted post-synaptic glutamate receptor. It is responsible for mediating rapid trans-synaptic signal transduction and hence believed to play a major role in seizure propagation. The three pivotal placebo-controlled trials of adjunctive perampanel demonstrated that the effective dosing range is 4–12 mg/day. The drug can be prescribed once daily, and its adverse effect profile is minimal with dizziness, fatigue, headache, and somnolence being the most commonly reported.

Conclusions

Perampanel is a welcome addition as it represents an alternative approach in the management of epilepsy with potential to have a significant impact on the prognosis of intractable epilepsy. However, it has only recently been licensed for clinical use in Europe, the USA, and Canada, and there are no data directly comparing it with other AEDs; hence, it remains far too early to ascertain its place in the treatment of patients with partial epilepsy.

Epilepsy, antiseizure therapy, and sleep cycle parameters

A reciprocal relationship exists between sleep and epilepsy. The quality of sleep is affected by the presence and frequency of seizures, type of antiepileptic therapy utilized, and coexisting primary sleep disorders. Daytime somnolence is one of the most common adverse effects of antiepileptic therapy, with specific pharmacologic agents exhibiting a unique influence on components of sleep architecture. The newer generation of antiseizure drugs demonstrates improved sleep efficiency, greater stabilization of sleep architecture, prolongation of REM sleep duration, and increased quality of life measures. The emerging field of chronoepileptology explores the relationship between seizures and circadian rhythms, aiming for targeted use of antiseizure therapies to maximize therapeutic effects and minimize the adverse events experienced by the patients.

New drug classes for the treatment of partial onset epilepsy: focus on perampanel

Perampanel (2-[2-oxo-1-phenyl-5-pyridin-2-yl-1,2-dihydropyridin-3-yl] benzonitrile hydrate) is the latest in the line of new antiepileptic drugs with a novel mechanism of action. Perampanel inhibits α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA)-induced increases in intracellular Ca²⁺ and selectively blocks AMPA receptor-mediated synaptic transmission, thus reducing neuronal excitation. Three Phase III multicenter, randomized, double-blind, placebo-controlled trials demonstrated the efficacy and good tolerability of perampanel as adjunctive treatment in patients with refractory partial-onset seizures. The drug is approved for use in the European Union and United States, with expected release onto the American market in June–September 2013, pending US Drug Enforcement Agency classification. The pharmacology of perampanel offers potential as more than just another new antiepileptic drug. This first-in-class drug will provide another option for practitioners of rational polytherapy. As an AMPA-receptor antagonist, perampanel may possess antiepileptogenic properties in addition to its demonstrated antiseizure properties.

Recent and Emerging Anti-seizure Drugs: 2013

OPINION STATEMENT

Recent and emerging pharmacotherapies have become available for use within the last 4 years to enhance our ability to manage people with epilepsy (PWE). More antiseizure drug (ASD) choices allow greater opportunity to match a unique medicine with each patient from the time of first seizure and for drug-resistant epilepsy. Balancing the efficacy, safety, and tolerability of an ASD is unique for each person and epilepsy syndrome. This tailored approach to effectiveness includes seven new ASDs that have become available since 2009 to treat PWE expanding our armamentarium to more than two dozen ASDs in the US that are now available for use. "Which ASD is best?" is still a complex challenge that remains to be answered. Until the ASD is found that is a panacea for everyone, the role of new AEDs in the treatment of epilepsy lies in the hands of the clinician to address the overall needs of the person first and foremost. In this paper, the newest and emerging ASDs in 2013 are reviewed focusing on the pharmacology, efficacy, and adverse effects. Each ASD has benefits and risks and the ultimate role in clinical use will be established over time as experience with each agent grows.

Epilepsy: new drug targets and neurostimulation

Despite advances in the medical and surgical therapy for epilepsy, about 30% of patients do not achieve full seizure control. In the past 5 years new antiepileptic drugs have been approved for clinical use. Some of these drugs have unique, novel mechanisms of action. Overall efficacy of these agents, however, seems similar to other antiepileptic drugs. Vagus nerve stimulation is a well-established palliative therapy for medically resistant epilepsy. Neurostimulation, with newer devices and targets becoming available, is a rapidly expanding field in epileptology. Considerable development and research are still necessary before these newer techniques become the standard of care for the treatment of epilepsy.

Safety and tolerability of perampanel: a review of clinical trial data

The Phase II and Phase III clinical development program of perampanel is providing a wealth of data on the safety and tolerability of this alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist as an adjuvant treatment for refractory partial-onset seizures. In Phase II dose-finding studies, perampanel was associated with an acceptable tolerability profile up to the maximum evaluated dose of 12 mg/day. Subsequent multinational, multicenter, randomized, double-blind, placebo-controlled Phase III registration studies further supported the tolerability of perampanel across the dose range 2-12 mg/day, with interim data from ongoing extension studies indicating that safety outcomes may be maintained over several years. An analysis of the pooled Phase III data indicated that the frequency of adverse events reported with perampanel generally increased in a dose-dependent manner, and the most common adverse events were dizziness and somnolence. Overall, perampanel has been associated with an acceptable and consistent safety profile that is maintained over long-term settings.

Perampanel: expanding therapeutic options for patients with medically refractory secondary generalized convulsive seizures

To evaluate the efficacy of adjunctive, once-daily perampanel against secondarily generalized (SG) seizures in three Phase III trials (studies 304, 305, and 306) and their extension (study 307). The Phase III studies enrolled patients (≥ 12 years) with uncontrolled partial-onset seizures despite treatment with 1-3 concomitant antiepileptic drugs. Patients completing the core Phase III studies were eligible for the extension study. Endpoints included median percent change in SG seizure frequency, 50% responder (proportion of patients achieving a ≥ 50% reduction in SG seizure frequency), 75% response, and seizure-freedom rates. In total, 1480 patients were randomized and treated in the three perampanel Phase III trials. At baseline, 71.9% of placebo-treated and 68.4% of perampanel-treated patients had a history of SG seizures. In the individual core Phase III studies, perampanel (4-12 mg) reduced seizure frequency and improved responder rates. Consistent with this, in pooled analyses of the Phase III data, the median percent change in SG seizure frequency was -48.6%, -62.9%, and -53.3% with perampanel 4, 8, and 12 mg, respectively, vs -19.4% with placebo; 50% responder rates were 49.3%, 60.5%, and 53.7% vs 37.0% with placebo. More perampanel-treated patients had ≥ 75% reductions in SG seizure frequency, and seizure-freedom rates improved, compared with placebo. Improvements in seizure frequency and responder rate were maintained during the extension study. Perampanel consistently demonstrated efficacy against SG seizures when assessed using various endpoints. Furthermore, reductions in seizure frequency and improvements in responder rate were sustained with long-term perampanel treatment.

Development of perampanel in epilepsy

Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors play a key role in mediating glutamatergic transmission in the cortex. Perampanel (2-[2-oxo-1-phenyl-5-pyridin-2-yl-1,2-dihydropyridin-3-yl] benzonitrile) is a potent, orally active, highly selective, non-competitive AMPA-type glutamate receptor antagonist, identified via a focused discovery program at Eisai Research Laboratories. Development of perampanel as adjunctive therapy for the treatment of partial-onset seizures was planned in keeping with regulatory guidance and guidelines on antiepileptic drug (AED) development. This is the first AED with a specific action on glutamate-mediated excitatory neurotransmission to show evidence of efficacy and tolerability in reducing treatment-refractory partial-onset seizures in Phase III clinical trials. Perampanel (Fycompa(®)) has been approved in the EU and the United States for adjunctive treatment of partial-onset seizures.

Systematic review and meta-analysis of the efficacy and safety of perampanel in the treatment of partial-onset epilepsy

INTRODUCTION

Perampanel is a first-in-class antiepileptic drug approved for adjunctive treatment of partial-onset seizure in patients aged 12 years or older. Published randomised controlled trials (RCTs) had small sample sizes, and meta-analyses have included too few studies to draw conclusive results for the assessment of tolerability, efficacy and safety of perampanel. There is a need to conduct a meta-analysis with a larger dataset and an appropriate study design.

OBJECTIVE

The aim of this study was to systematically review the efficacy and safety of perampanel in the treatment of partial-onset epilepsy.

METHODS

Electronic and clinical trials databases were searched for RCTs of perampanel published up to March 2013. Outcomes of interest were 50 % responder rates, seizure freedom, treatment-emergent adverse events (TEAEs) and incidence of withdrawal. Meta-analysis was performed to investigate the outcomes of interest.

RESULTS

Five RCTs with a total of 1,678 subjects were included. The 50 % responder rates were significantly greater in patients receiving 4, 8 and 12 mg perampanel versus placebo, with risk ratios of 1.54 (95 % CI 1.11-2.13), 1.80 (95 % CI 1.38-2.35) and 1.72 (95 % CI 1.17-2.52), respectively. There was no statistical evidence of a difference in seizure freedom between 8 or 12 mg perampanel and placebo. Of the five commonly reported TEAEs included, both dizziness and somnolence were statistically associated with 8 mg perampanel, whilst dizziness was statistically associated with 12 mg perampanel. Incidences of withdrawal due to adverse events were significantly higher in the 8 mg and 12 mg perampanel groups versus placebo.

CONCLUSION

The use of perampanel resulted in a statistically significant reduction of seizure frequency with respect to the 50 % responder rate in patients with partial-onset epilepsy. Perampanel is well tolerated at 4 mg and reasonably tolerated at 8 and 12 mg. Further clinical and pharmacovigilance studies are required to investigate the long-term efficacy and safety of perampanel in the management of other types of epilepsy.

Profile of perampanel and its potential in the treatment of partial onset seizures

Perampanel (PER) is a novel antiepileptic compound that decreases neuronal excitability by modulating glutamatergic transmission through selective noncompetitive blockade of AMPA receptors. PER has been evaluated in three pivotal placebo-controlled randomized trials as adjunctive therapy in adult drug-resistant partial epilepsy. In comparison to placebo, adjunctive PER effectively reduces seizure frequency. The relative risk of the responder rate (95% confidence interval [CI]) was thus 1.60 (1.08-2.36), 1.79 (1.42-2.25) and 1.66 (1.24-2.23) for once-daily PER 4 mg/day, 8 mg/day and 12 mg/day, respectively. The most common adverse events associated with PER were nonspecific central nervous system side effects. Some concerns have been raised about risk of clinically significant weight gain and of psychiatric adverse events. Long-term open-label extensions of the three pivotal trials are underway. PER has recently been approved both in Europe and in the USA for the adjunctive treatment of partial onset seizures in patients aged 12 years and above. However, in the absence of a direct comparison between PER and other licensed antiepileptic drugs' efficacy and tolerability, the clinical advantages of PER over the other drugs in intractable partial epilepsy remains to be determined.

Perampanel: as adjunctive therapy in patients with partial-onset seizures

Perampanel is a novel antiepileptic drug (AED) used as adjunctive therapy in adolescents and adults with partial-onset seizures (with or without secondarily generalized seizures). It is a selective, noncompetitive antagonist of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors on post-synaptic neurons, and is the first in this new class of AED known as AMPA receptor antagonists. In three randomized, double-blind, placebo-controlled, phase III trials in adolescent and adult patients with refractory partial-onset seizures, once-daily administration of perampanel 4, 8 and 12 mg/day (6-week titration phase followed by 13-week maintenance phase), as adjunctive therapy with one to three AEDs, was statistically superior to adjunctive placebo in achieving the key efficacy endpoints of the median percentage change from baseline in seizure frequency and/or the proportion of patients with a ≥50 % reduction in seizure frequency relative to baseline. Adverse events were usually mild or moderate in severity and the most frequent treatment-emergent events reported among perampanel recipients were CNS-related, such as dizziness, somnolence, headache and fatigue. Interim data from a large extension study (16-week blinded conversion period followed by open-label maintenance phase), which enrolled patients who completed the phase III trials, showed a similar group response for the reduction in seizure frequency over at least 1 year of adjunctive treatment with perampanel. Perampanel was generally well tolerated over the longer-term in extension studies, with no unexpected adverse events reported. On the basis of its overall clinical profile and unique mechanism of action, perampanel is a useful adjunctive treatment option in patients with refractory partial-onset seizures.