The adverse event profile of perampanel: meta-analysis of randomized controlled trials

Long-term treatment with Perampanel of Chinese patients with focal-onset seizures, especially in sleep-related epilepsy: a prospective real-world observational study

Background

There is currently a lack of studies examining the long-term therapeutic effectiveness of the third-generation anti-sezure medication, perampanel (PER), for focal-onset seizures (FOS), particularly in Chinese patients with sleep-related epilepsy (SRE). Additionally, the appropriate dosage, plasma concentration, and the relationship between dose and plasma concentration of PER in Chinese patients are still uncertain.

Methods

A prospective, single-center, 24-month observational study was conducted in patients diagnosed with FOS, with a focus on patients with SRE. Changes in seizure frequency from baseline, adverse events, and retention rates were analyzed at 12 and 24 months following the start of the treatment. Tolerability was evaluated based on adverse events and discontinuation profiles. PER plasma concentrations were used to assess dose-concentration-response relationships.

Results

A total of 175 patients were included (median age: 25 years; range: 4-72 years; 53. 1% males and 46.9% females), with the SRE population accounting for 49. 1% (n = 86). The patients diagnosed with SRE showed considerably higher response rates than those who did not have this diagnosis (p = 0.025, odds ratio = 3.8). Additionally, the SRE group adhered better to PER treatment (r = 0.0009). Patients with a shorter duration of epilepsy (median: 3 years; range:2-7 years) demonstrated a more favorable therapeutic response to PER (p = 0.032). Throughout the administration of maintenance doses, among the entire FOS population, the concentration of PER (C0) ranged between 101.5 and 917.4 ng/mL (median, 232.0 ng/mL), and the mean plasma concentration of PER in the responders was 292.8 ng/mL. We revealed a linear relationship between PER dose and plasma concentration, regardless of whether PER was used as monotherapy or add-on therapy. The retention rates were 77.7% and 65. 1% at 12 and 24 months, respectively. Drug-related adverse events occurred in 45.0% of the patients and were mostly manageable.

Conclusion

PER effectively reduced seizure frequency in Chinese patients with FOS, particularly in those with SRE, over a 24-month period. The treatment was well-tolerated and had a clear linear dose-plasma concentration relationship.

Intrinsic brain activity differences in perampanel-responsive and non-responsive drug-resistant epilepsy patients: an EEG microstate analysis

Background

Drug-resistant epilepsy (DRE) patients exhibit aberrant large-scale brain networks. Perampanel may be a therapeutic option for controlling seizures in these patients.

Objective

We aim to explore the differences of resting-state electroencephalogram (EEG) microstate in perampanel-responsive and non-responsive DRE patients.

Design

Retrospective study.

Methods

Clinical data were collected from DRE patients who received perampanel treatment at the Fujian Medical University Union Hospital from June 2020 to September 2021, with a minimum follow-up of 6 months. Patients were classified into three groups based on the extent of reduction in seizure frequency: non-responsive (seizure reduction <50%), responsive (seizure reduction >50% but not seizure-free), and seizure-free. Resting-state EEG data sets of all participants were subjected to EEG microstate analysis. The study comprehensively compared the mean duration, frequency per second, and temporal coverage of each microstate among the three groups.

Results

A total of 76 perampanel-treated DRE patients were categorized into three groups based on their response to treatment: non-responsive (n = 20), responsive (n = 36), and seizure-free (n = 20), according to the degree of seizure frequency reduction. The results of EEG microstate analysis revealed no statistically significant distinctions in frequency, duration, and coverage of microstate D in these DRE patients. However, the seizure-free group showed significantly increased duration and coverage of microstate A, frequency and coverage of microstate B, and significantly decreased duration, frequency, and coverage of microstate C when compared with the other groups.

Conclusion

Microstate A, B, and D is associated with the sensorimotor network, visual network, salience network, and attention network, respectively. This study demonstrates statistically significant differences in the sensorimotor, visual, and salience networks, but not in the attention network, between perampanel-responsive and non-responsive DRE patients.

Adverse Event Profiles of Antiseizure Medications and the Impact of Coadministration on Drug Tolerability in Adults with Epilepsy

BACKGROUND

Antiseizure medication (ASM) as monotherapy or in combination is the treatment of choice for most patients with epilepsy. Therefore, knowledge about the typical adverse events (AEs) for ASMs and other coadministered drugs (CDs) is essential for practitioners and patients. Due to frequent polypharmacy, it is often difficult to clinically assess the AE profiles of ASMs and differentiate the influence of CDs.

OBJECTIVE

This retrospective analysis aimed to determine typical AE profiles for ASMs and assess the impact of CDs on AEs in clinical practice.

METHODS

The Liverpool AE Profile (LAEP) and its domains were used to identify the AE profiles of ASMs based on data from a large German multicenter study (Epi2020). Following established classifications, drugs were grouped according to their mode of action (ASMs) or clinical indication (CDs). Bivariate correlation, multivariate ordinal regression (MORA), and artificial neural network (ANNA) analyses were performed. Bivariate correlation with Fisher's z-transformation was used to compare the correlation strength of LAEP with the Hospital Anxiety and Depression Scale (HADS) and Neurological Disorders Depression Inventory for Epilepsy (NDDI-E) to avoid LAEP bias in the context of antidepressant therapy.

RESULTS

Data from 486 patients were analyzed. The AE profiles of ASM categories and single ASMs matched those reported in the literature. Synaptic vesicle glycoprotein 2A (SV2A) and voltage-gated sodium channel (VGSC) modulators had favorable AE profiles, while brivaracetam was superior to levetiracetam regarding psychobehavioral AEs. MORA revealed that, in addition to seizure frequency, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) modulators and antidepressants were the only independent predictors of high LAEP values. After Fisher's z-transformation, correlations were significantly lower between LAEP and antidepressants than between LAEP and HADS or NDDI-E. Therefore, a bias in the results toward over interpreting the impact of antidepressants on LAEP was presumed. In the ANNA, perampanel, zonisamide, topiramate, and valproic acid were important nodes in the network, while VGSC and SV2A modulators had low relevance for predicting relevant AEs. Similarly, cardiovascular agents, analgesics, and antipsychotics were important CDs in the ANNA model.

CONCLUSION

ASMs have characteristic AE profiles that are highly reproducible and must be considered in therapeutic decision-making. Therapy using perampanel as an AMPA modulator should be considered cautiously due to its relatively high AE profile. Drugs acting via VGSCs and SV2A receptors are significantly better tolerated than other ASM categories or substances (e.g., topiramate, zonisamide, and valproate). Switching to brivaracetam is advisable in patients with psychobehavioral AEs who take levetiracetam. Because CDs frequently pharmacokinetically interact with ASMs, the cumulative AE profile must be considered.

TRIAL REGISTRATION

DRKS00022024, U1111-1252-5331.

The safety of perampanel in different disorders and doses: A meta-analysis

PURPOSE

To investigate the safety of perampanel in different disorders and doses.

METHODS

Embase, the Cochrane Library, Medline, and ClinicalTrials.gov were searched from inception to July 2022 for randomized controlled trials (RCTs). The meta-analysis was performed by using Review Manager 5.3 and R 4.2.1 software.

RESULTS

A total of 17 RCTs with 5711 subjects were included in the final analysis. The double-blind treatment phase was from 12 weeks to 48 weeks. Our results showed that 11 adverse events (aggression, ataxia, balance disorder, dizziness, fall, fatigue, irritability, rash, somnolence, vertigo, and weight increase) were statistically significantly associated with perampanel, and 4 of them (ataxia, dizziness, fatigue, and somnolence) showed a clear dose-response relationship. Psychiatric adverse events occurred most frequently among serious treatment-emergent adverse events (TEAEs). At 8 mg/day, seven adverse events (aggression, balance disorder, dizziness, fatigue, irritability, vertigo, and weight increase) occurred more frequently in patients with epilepsy than in patients with other disorders, whereas dose discontinuation rates due to adverse events were lower in patients with epilepsy than in patients with other disorders.

CONCLUSION

The safety profile of perampanel is dependent on diseases and dose. The risk of adverse events was statistically significantly higher, with doses exceeding 4 mg/day. Despite a higher risk of adverse events, patients with epilepsy had a lower perampanel discontinuation rate than patients with other disorders.

A Case of Perampanel Overdose Presenting with Respiratory Failure

Perampanel is a novel antiepileptic drug that has been used as an adjunctive treatment for focal-onset seizures. No reports to date have documented respiratory suppression as a side effect of perampanel in adults. Herein, we report a 51-year-old man with focal epilepsy presented with type 2 respiratory failure after accidently consuming of 66 mg of perampanel. Clinicians should consider the possibility of respiratory compromise whenever a high dose of perampanel needs to be administered to patients.

Impact of Antiseizure Medications on Appetite and Weight in Children

There are numerous potential factors that may affect growth in children with epilepsy, and these must be evaluated in any child with appetite and weight concerns. Antiseizure medications (ASMs) have potential adverse effects, and many may affect appetite, thus impacting normal growth and weight gain. The aim of this review is to focus on the impact of both epilepsy and ASMs on appetite and weight in children. We systematically reviewed studies using Medline assessing the impact of ASMs on appetite and weight in children. Eligible studies included randomized controlled trials and open-label studies (open-label extension and interventional) that targeted or included the pediatric population (0-18 years of age). Each study was classified using the American Academy of Neurology (AAN) Classification of Evidence for Therapeutic Studies, and the level of evidence for impact on appetite and weight in children was graded. ASMs associated with decreased appetite and/or weight loss include fenfluramine, topiramate, zonisamide, felbamate, rufinamide, stiripentol, cannabidiol, brivaracetam and ethosuximide; ASMs with minimal impact on weight and appetite in children include oxcarbazepine, eslicarbazepine, lamotrigine, levetiracetam, lacosamide, carbamazepine, vigabatrin and clobazam. The ASM most robustly associated with increased appetite and/or weight gain is valproic acid; however, both pregabalin and perampanel may also lead to modest weight gain or increased appetite in children. Certain ASMs may impact both appetite and weight, which may lead to increased morbidity of the underlying disease and impaired adherence to the treatment regimen.

Drugs for patients with epilepsy and excessive daytime sleepiness

Excessive daytime sleepiness (EDS) and attentional deficits are often observed in people with epilepsy. They may be the consequence of seizures and subclinical discharges as well as of comorbid conditions as obstructive sleep apnea/hypopnea syndrome (OSAS), attention deficit hyperactivity disorder (ADHD), or other less frequent disorders. Excessive daytime sleepiness may also be caused or worsened by antiseizure medications (ASMs). Several meta-analyses suggested that lamotrigine, lacosamide, and perhaps eslicarbazepine are less sedative than other traditional and new ASMs and, in patients prone to somnolence, might be preferred over ASMs with more sedative properties. In patients with severe EDS and/or ADHD, advantages and risks of a treatment with a psychostimulant need to be considered. Methylphenidate, modafinil, armodafinil, pitolisant, and solriamfetol are authorized for use in ADHD and EDS in patients with narcolepsy and some of them also in OSAS. These agents are off-label for the treatment of EDS associated with epilepsy. They do not have proconvulsant effects, although there are several possible risks for patients with epilepsy. The risks of cardiovascular events and psychiatric symptoms should be carefully evaluated as such disorders can coexist with epilepsy and be triggered by these agents. Finally, combination of psychostimulants with ASMs may be associated with several pharmacokinetic drug-drug interactions.

An Open-Label Phase 2a Study to Evaluate the Safety and Tolerability of Perampanel in Cervical Dystonia

Background

Cervical dystonia (CD) is the most common focal isolated dystonia. Preclinical studies report that AMPA-selective glutamate receptor antagonists improve dystonia. Perampanel is a clinically available, AMPA receptor antagonist that has shown efficacy and safety in epilepsy.

Objectives

To determine safety and tolerability of perampanel in CD.

Methods

We performed a phase 2a, open-label, multicenter study to evaluate tolerability and safety of perampanel in CD. Included subjects had primary CD; those on botulinum toxin were 8 weeks post last injection. All subjects received perampanel 2 mg/day, titrated 2 mg weekly over 6 weeks, to maximum 12 mg/day; maintenance phase was 4 weeks, ending at week 10. Primary endpoints included tolerability, defined as ability to remain on perampanel for the maintenance period, at any dose level and safety, determined from adverse events (AEs) collected at each visit. Secondary exploratory endpoints included Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS), quality of life (cervical dystonia impact profile [CIDP]-58) and Clinical Global Impression of change (CGI).

Results

CD participants (n = 25) were recruited. Eight subjects withdrew; 4 because of AEs, 3 for other reasons and 1 lost to follow up. One subject tolerated 12 mg/day. Eight subjects (30.8%) tolerated 2 mg, whereas 19.2% tolerated 4 mg/day, and 15.4% tolerated 6 mg or 8 mg/day. All subjects experienced AEs. The most common AEs were dizziness, imbalance, and irritability. Exploratory endpoints of TWSTRS showed some improved pain scores and CIDP-58 improved sleep.

Conclusions

Tolerability to perampanel was variable in CD subjects. Lower doses would be considered for future studies in this population.

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.

Mechanisms Underlying Aggressive Behavior Induced by Antiepileptic Drugs: Focus on Topiramate, Levetiracetam, and Perampanel

Antiepileptic drugs (AEDs) are effective against seizures, but their use is often limited by adverse effects, among them psychiatric and behavioral ones including aggressive behavior (AB). Knowledge of the incidence, risk factors, and the underlying mechanisms of AB induced by AEDs may help to facilitate management and reduce the risk of such side effects. The exact incidence of AB as an adverse effect of AEDs is difficult to estimate, but frequencies up to 16% have been reported. Primarily, levetiracetam (LEV), perampanel (PER), and topiramate (TPM), which have diverse mechanisms of action, have been associated with AB. Currently, there is no evidence for a specific pharmacological mechanism solely explaining the increased incidence of AB with LEV, PER, and TPM. Serotonin (5-HT) and GABA, and particularly glutamate (via the AMPA receptor), seem to play key roles. Other mechanisms involve hormones, epigenetics, and “alternative psychosis” and related phenomena. Increased individual susceptibility due to an underlying neurological and/or a mental health disorder may further explain why people with epilepsy are at an increased risk of AB when using AEDs. Remarkably, AB may occur with a delay of weeks or months after start of treatment. Information to patients, relatives, and caregivers, as well as sufficient clinical follow-up, is crucial, and there is a need for further research to understand the complex relationship between AED mechanisms of action and the induction/worsening of AB.

Safety and tolerability profile of new antiepileptic drug treatment in children with epilepsy

INTRODUCTION

Treatment of pediatric epilepsy requires a careful evaluation of the safety and tolerability profile of antiepileptic drugs (AEDs) to avoid or minimize as much as possible adverse events (AEs) on various organs, hematological parameters, and growth, pubertal, motor, cognitive and behavioral development.

AREAS COVERED

Treatment-emergent AEs (TEAEs) reported in the literature 2000-2018 regarding second- and third-generation AEDs used in the pediatric age, with exclusion of the neonatal period that exhibits specific peculiarities, have been described on the basis of their frequency, severity/tolerability, and particular association with a given AED.

EXPERT OPINION

Somnolence/sedation and behavioral changes, like irritability and nervousness, are among the most commonly observed TEAEs associated with almost all AEDs. Lamotrigine, Gabapentin, Oxcarbazepine, and Levetiracetam appear to be the best-tolerated AEDs with a ≤2% withdrawal rate, while Tiagabine and Everolimus are discontinued in up to >20% of the patients because of intolerable TEAEs. For some AEDs, literature data are scanty to draw a high-level evidence on their safety and tolerability profile. The reasons are: insufficient population size, short duration of treatments, or lack of controlled trials. A future goal is that of identifying clearer, easier, and more homogeneous methodological strategies to facilitate AED testing in pediatric populations.

The effects of AMPA receptor blockade on resting magnetoencephalography recordings

The ionotropic N-methyl-D-aspartate and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors of the glutamatergic neurotransmitter system are of fundamental importance to healthy brain function. Neuroimaging studies in humans have previously been conducted using various drugs that interact with N-methyl-D-aspartate glutamate receptors, but no such studies have investigated AMPA receptor signalling. The recent approval of perampanel (Fycompa) for use in humans provides a means to specifically study the role of AMPA receptors in the pharmacological basis of neuroimaging signals. Twenty male subjects participated in this placebo-controlled crossover study that consisted of two study days separated by a minimum two-week washout period. On one occasion participants ingested a 6 mg dose of perampanel, and on the other a placebo. Ten minutes of wakeful rest was recorded before and after each dose using magnetoencephalography. Subjective ratings of intoxication were significantly higher following drug than placebo. Cluster-based randomisation testing of sensor-level magnetoencephalography data showed significant drug-induced increases in low frequency power (1-4 Hz, 4-8 Hz, 8-13 Hz, 13-30 Hz), along with a significant decrease in the high gamma range (50-90 Hz). We also observed selective increases in functional connectivity in the alpha and beta bands. The findings are consistent with preclinical work and are similar to the spectral profile of other anti-epileptic drugs.

Indirect comparison of third-generation antiepileptic drugs as adjunctive treatment for uncontrolled focal epilepsy

PURPOSE

Eslicarbazepine (ESL), Lacosamide (LAC), Perampanel (PER) and Brivaracetam (BRV), have recently been marketed as third-generation antiepileptic drugs (AEDs). We conducted a meta-analysis to indirectly compare overall efficacy and tolerability between third-generation AEDs in uncontrolled focal epilepsy.

METHODS

We performed an online database search using Pubmed, Embase, Cochrane Online Library, and Clinicaltrial.gov for all available randomized controlled trials (RCTs) that investigated the therapeutic effects over a range of AED doses versus placebo. We then compared clinical efficacy and tolerability between these newer AEDs using Indirect Treatment Comparison software.

RESULTS

Nineteen RCTs with a total of 7245 patients were included in our study. There were no significant differences in the risk difference of 50% responder rates and seizure free rates between third generation AEDs, regardless of dose. The risk of treatment emergent adverse events was significantly higher with ESL and PER treatment compared to BRV at all doses combined. Withdrawal rates due to adverse events were also significantly higher in patients treated with the highest doses of LAC and PER versus BRV, while treatment with ESL or LAC was related to higher withdrawal rates versus BRV when all doses were combined.

CONCLUSIONS

Our analysis suggested there were no significant differences in efficacy between third generation AEDs in uncontrolled focal epilepsy. BRV may have the best tolerability profile. The other AEDs were associated with a higher risk for intolerable adverse, especially when taken at a high doses. The results from these indirect comparisons warrant further examination and verification through future well-designed trials.

Epilepsy, Antiepileptic Drugs, and Aggression: An Evidence-Based Review

Antiepileptic drugs (AEDs) have many benefits but also many side effects, including aggression, agitation, and irritability, in some patients with epilepsy. This article offers a comprehensive summary of current understanding of aggressive behaviors in patients with epilepsy, including an evidence-based review of aggression during AED treatment. Aggression is seen in a minority of people with epilepsy. It is rarely seizure related but is interictal, sometimes occurring as part of complex psychiatric and behavioral comorbidities, and it is sometimes associated with AED treatment. We review the common neurotransmitter systems and brain regions implicated in both epilepsy and aggression, including the GABA, glutamate, serotonin, dopamine, and noradrenaline systems and the hippocampus, amygdala, prefrontal cortex, anterior cingulate cortex, and temporal lobes. Few controlled clinical studies have used behavioral measures to specifically examine aggression with AEDs, and most evidence comes from adverse event reporting from clinical and observational studies. A systematic approach was used to identify relevant publications, and we present a comprehensive, evidence-based summary of available data surrounding aggression-related behaviors with each of the currently available AEDs in both adults and in children/adolescents with epilepsy. A psychiatric history and history of a propensity toward aggression/anger should routinely be sought from patients, family members, and carers; its presence does not preclude the use of any specific AEDs, but those most likely to be implicated in these behaviors should be used with caution in such cases.

AMPA GluA1-flip targeted oligonucleotide therapy reduces neonatal seizures and hyperexcitability

Glutamate-activated α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPA-Rs) mediate the majority of excitatory neurotransmission in brain and thus are major drug targets for diseases associated with hyperexcitability or neurotoxicity. Due to the critical nature of AMPA-Rs in normal brain function, typical AMPA-R antagonists have deleterious effects on cognition and motor function, highlighting the need for more precise modulators. A dramatic increase in the flip isoform of alternatively spliced AMPA-R GluA1 subunits occurs post-seizure in humans and animal models. GluA1-flip produces higher gain AMPA channels than GluA1-flop, increasing network excitability and seizure susceptibility. Splice modulating oligonucleotides (SMOs) bind to pre-mRNA to influence alternative splicing, a strategy that can be exploited to develop more selective drugs across therapeutic areas. We developed a novel SMO, GR1, which potently and specifically decreased GluA1-flip expression throughout the brain of neonatal mice lasting at least 60 days after single intracerebroventricular injection. GR1 treatment reduced AMPA-R mediated excitatory postsynaptic currents at hippocampal CA1 synapses, without affecting long-term potentiation or long-term depression, cellular models of memory, or impairing GluA1-dependent cognition or motor function in mice. Importantly, GR1 demonstrated anti-seizure properties and reduced post-seizure hyperexcitability in neonatal mice, highlighting its drug candidate potential for treating epilepsies and other neurological diseases involving network hyperexcitability.

Two-year real-world experience with perampanel in patients with refractory focal epilepsy: Austrian data

BACKGROUND

The aim of this study was to analyse registry data of seizure outcome and adverse events (AEs) for perampanel as add-on therapy in patients with focal epilepsy since its approval in 2012 for adjunctive treatment of focal epilepsy in patients ⩾12 years.

METHOD

A retrospective 2-year chart review of all patients receiving perampanel was carried out.

RESULTS

A total of 122 patients received perampanel [median treatment length: 20.1 (range: 3.4-26.8) months]; 71 (58%) remained on treatment at last follow up. Overall, 33 patients (27%) were seizure-free for ⩾3 months at last follow up; of these, eight were seizure free for ⩾3 times the longest interictal interval before perampanel therapy; 18 (15%) had reduced seizure frequency ⩾50%. A total of 58 (47%) had an AE and 34 (28%) withdrew from treatment because of AEs. AEs included dizziness (33%), fatigue (12%), psychiatric symptoms (8%), cognitive deficits (7%), speech problems (5%), nausea (4%) and gait problems (4%). AEs subsided in 17/18 patients (94%) following a 2 mg dose reduction. A total of 43 (35%) took a concomitant enzyme inducer. Patients not taking enzyme inducers were more likely to be seizure free (p = 0.002); there were no other between-group differences.

CONCLUSIONS

Perampanel was well tolerated and improved seizure control in 42% of patients (50- 100% reduction), with higher rates in those not receiving a concomitant enzyme inducer. AEs, particularly dizziness, were common but often disappeared with a slight dose reduction. The results are consistent with those from randomized controlled trials.

New antiepileptic drugs: focus on ezogabine, clobazam, and perampanel

Ezogabine, clobazam, and perampanel are among the newest antiseizure drugs approved by the Food and Drug Administration between 2011 and 2012. Ezogabine and perampanel are approved for adjunctive treatment of partial epilepsy. Perampanel is also approved for adjunctive treatment of primary generalized tonic–clonic seizures. Ezogabine and perampanel have novel mechanisms of action. Ezogabine binds to voltage-gated potassium channels and increases the M-current thereby causing membrane hyperpolarization. Perampanel is a selective, non-competitive 2-amino-3-(3-hydroxy-5-methyl-isoxazol-4-yl)propanoic acid receptor antagonist, which reduces neuronal excitation. Clobazam has been used worldwide since the 1970s and is approved for adjunctive treatment of seizures associated with Lennox-Gastaut syndrome. Clobazam is the only 1,5-benzodiazepine currently in clinical use, which is less sedating than the commonly used 1,4-benzodiazepines. Phase III multicenter, randomized, double-blind, placebo-controlled trials demonstrated efficacy and good tolerability of these 3 new antiepileptic drugs. These drugs represent a welcome addition to the armamentarium of practitioners, but it remains to be seen how they will affect the landscape of pharmacoresistant epilepsy.

Prospective audit with adjunctive perampanel: Preliminary observations in focal epilepsy

PURPOSE

Perampanel (PER) was first licensed in the United Kingdom in 2012 for the adjunctive treatment of focal seizures with or without secondary generalization in adults and children over 12years of age. It has recently also been approved for use as add-on therapy for patients with primary generalized tonic-clonic seizures. This prospective audit reports preliminary outcomes with adjunctive PER in patients with focal-onset seizures in everyday clinical practice using a standard design.

METHODS

To date, 54 patients (38 males, 16 females; 21-65years, median: 48years) have completed the study. The median monthly seizure frequency was 4 (range: 1-60). At baseline, patients were taking a median of 2 other antiepileptic drugs (range: 1-4 drugs), with their seizures having previously failed to improve on a median of 3 schedules (range: 1-15 schedules). After 12weeks of stable dosing, PER was added, aiming at a target range of 6-12mg/daily. Review took place every 6-8weeks until one of 4 endpoints was reached: seizure freedom for ≥6months on a given PER dose, ≥50% (responder) or <50% (marginal effect) seizure reduction over 6months, compared with the prospective baseline, on the highest tolerated PER dose, or withdrawal of PER due to a lack of efficacy or side effects.

RESULTS

Three (5.6%) patients have remained seizure-free, with 8 (14.8%) demonstrating a ≥50% response and a further 17 (31.5%) reporting a marginal effect. Of the 26 (48.1%) dropping out of PER treatment, 21 (38.9%) did so because of side effects. The commonest problems were nausea, vomiting, ataxia, dizziness, and sedation. Overall, 6 (11%) patients developed neuropsychiatric problems, with 3 reporting irritability and/or aggression. Two patients had substantial weight gain, and another patient suffered recurrent falls. Treatment with enzyme-inducing AEDs had no effect on PER dosing in patients responding to PER or withdrawing due to side effects.

SIGNIFICANCE

These data support the value of adjunctive PER in some patients with pharmacoresistant epilepsy in everyday clinical practice.

Practical Use of Newer Antiepileptic Drugs as Adjunctive Therapy in Focal Epilepsy

This article lays the background for, and discusses the practical issues surrounding, the adjunctive use of the last four antiepileptic drugs (AEDs) to be licensed for the treatment of pharmacoresistant focal seizures in the UK and elsewhere. More than 30% of adolescent and adult patients will not be fully controlled on the currently available therapeutic armamentarium. After not responding to their first three AED schedules, only a handful of patients attained seizure freedom on subsequent regimens. To optimise the response to any new AED in this setting, it is often necessary to reduce the existing drug burden. The pharmacology, tolerability and safety, and everyday use of lacosamide, eslicarbazepine acetate, retigabine (ezogabine) and perampanel will be reviewed and discussed. This will be accompanied by data from prospective audits with each drug undertaken at the Western Infirmary in Glasgow, Scotland, and a report of their successful introduction in an illustrative case. Overall, there is a large variation in the course of refractory epilepsy and the effect of AED therapy on this process seems minimal. Nevertheless, a number of patients will benefit from the introduction of each new AED, with some becoming seizure-free.

Pharmacogenetics of adverse reactions to antiepileptic drugs

INTRODUCTION

Adverse drug reactions (ADRs) are a major public health concern and a leading cause of morbidity and mortality in the world. In the case of antiepileptic drugs (AEDs), ADRs constitute a barrier to successful treatment since they decrease treatment adherence and impact patients' quality of life of patients. Pharmacogenetics aims to identify genetic polymorphisms associated with drug safety. This article presents a review of genes coding for drug metabolising enzymes and drug transporters, and HLA system genes that have been linked to AED-induced ADRs.

DEVELOPMENT

To date, several genetic variations associated with drug safety have been reported: CYP2C9*2 and *3 alleles, which code for enzymes with decreased activity, have been linked to phenytoin (PHT)-induced neurotoxicity; GSTM1 null alleles with hepatotoxicity induced by carbamazepine (CBZ) and valproic acid (VPA); EPHX1 polymorphisms with teratogenesis; ABCC2 genetic variations with CBZ- and VPA-induced neurological ADRs; and HLA alleles (e.g. HLA-B*15:02, -A*31:01, -B*15:11, -C*08:01) with cutaneous ADRs.

CONCLUSIONS

Published findings show that there are ADRs with a pharmacogenetic basis and a high interethnic variability, which indicates a need for future studies in different populations to gather more useful results for larger number of patients. The search for biomarkers that would allow predicting ADRs to AEDs could improve pharmacotherapy for epilepsy.

Treatment of the later stages of Parkinson's disease - pharmacological approaches now and in the future

The problems associated with the pharmacological treatment of the later stages of Parkinson's disease (PD) remain those seen over many years. These centre on a loss of drug effect ('wearing off') with disease progression, the occurrence of dyskinesia, notably with L-dopa use and the appearance of non-motor symptoms that are largely refractory to dopaminergic medication. Treatment strategies in late PD have been dominated by the use of drug combinations and the subtle manipulation of drug dosage. However, change is occurring as the understanding of the basis of motor complications and fluctuations and non-motor symptoms improves. New pharmacological options are expanding with the advent of longer acting versions of existing dopaminergic drugs, new drug delivery systems and the introduction of non-dopaminergic agents able to manipulate motor function both within the basal ganglia and in other brain regions. Non-dopaminergic agents are also being investigated for the treatment of dyskinesia and for the relief of non-motor symptoms. However, while therapy continues to improve, the treatment of late stage PD remains problematic with non-motor symptoms dominating the unmet need in this patient group.

Clinical experience with perampanel: focus on psychiatric adverse effects

BACKGROUND

Perampanel (PER) is a novel antiepileptic drug that inhibits the AMPA class of glutamate receptors. It has been available in the UK since September 2012. We undertook a retrospective analysis of efficacy and tolerability of PER in 47 patients with drug-refractory epilepsy attending a regional epilepsy service in the UK.

METHODS

Demographic and clinical data of patients with refractory epilepsy prescribed PER were collected by review of records. Efficacy, as measured by responder rates (>50% reduction in seizure frequency), retention rates, and adverse effects, was analyzed.

RESULTS

Of the 47 patients prescribed PER, 39 (87%) had focal epilepsy, four (9%) had idiopathic generalized epilepsy, 3 (6%) had symptomatic generalized epilepsy, and 1 had unclassified epilepsy. Patients were taking a median of 2 AEDs (range: 1-5) when starting on PER. The median dose of PER was 8 mg (range: 2-12 mg). Thirteen (28%) patients were classed as responders, but no patients experienced sustained seizure freedom. Twenty-one (45%) patients had withdrawn from PER during the study period, with 16 (76%) of them withdrawing due to intolerable adverse effects, 4 due to inadequate seizure control, and 1 due to the combination of both. The most frequent adverse effects requiring withdrawal from PER were behavioral reactions including suicidal ideation (n = 2), aggressive behavior (n = 2), and both (n = 1).

CONCLUSION

In our experience, PER had a retention rate of 55% and a responder rate of 28%. Psychiatric adverse effects, including suicidal ideation, were the most common reasons for withdrawal.

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.