Pharmacokinetic/pharmacodynamic analysis of adjunctive perampanel in subjects with partial-onset seizures

Population pharmacokinetics and dosing optimization of perampanel in children with epilepsy: A real-world study

OBJECTIVE

The purposes of this study were to explore the pharmacokinetics of perampanel (PER) in children with epilepsy, identify factors that contribute to pharmacokinetic variations among subjects, evaluate the connection between PER exposure and clinical outcome, and establish an evidence-based approach for tailoring individualized antiepileptic treatment in this specific population.

METHODS

In this prospective study, PER plasma concentrations and genetic information on metabolic enzymes were obtained from 194 patients younger than 18 years. The disposition kinetics of PER in pediatric patients following oral dosing were characterized using nonlinear mixed effect models. The effective range for the plasma concentration of PER was determined by assessing the efficacy and safety of PER treatment and analyzing the relationship between drug exposure and clinical response. Monte Carlo simulations were then performed to evaluate and optimize the current dosing regimens.

RESULTS

The pharmacokinetic profile of PER was adequately described by a one-compartment model with first-order absorption and elimination. Body weight, total bilirubin level, and concomitant oxcarbazepine were found to have significant influences on PER pharmacokinetics. Model estimates of apparent clearance and volume of distribution were .016 ± .009 L/h/kg and 1.47 ± .78 L/kg, respectively. The effective range predicted from plasma concentration data in responders was 215-862 μg/L. Dosing scenarios stratified according to essential covariates were proposed through simulation analysis.

SIGNIFICANCE

In this study, we captured the pharmacokinetic/pharmacodynamic characteristics of PER in pediatric epilepsy patients through analysis of real-world data and adopted a pharmacometric approach to support an individualized dosing strategy for PER in this specific population.

Demographic Diversity of Clinical Trials for Therapeutic Drug Products: A Systematic Review of Recently Published Articles, 2017-2022

The US Food and Drug Administration (FDA) encourages the use of enrollment practices that will lead to clinical trials that reflect the population most likely to use the therapeutic product (drug or biologic), if approved. In doing so, the benefit-risk profile of the product may be assessed more completely and offer patients and their health care providers a better understanding of the drug profile and greater confidence in clinical trial results. The objective of this systematic review was to assess recent literature on the demographic diversity of clinical trial participants, describe the methods used in defining clinical trial diversity, and address knowledge gaps to enhance clinical trial diversity. Our literature search initially yielded 246 articles. After applying our eligibility criteria, we conducted a full-text review and analyzed the contents of the 28 remaining articles in our systematic review. Eleven (39%) of the 28 articles used a reference standard to compare the participation of populations in clinical trials to assess diversity. The majority of the 28 articles reported on adult participants; only 5 included pediatric populations. Most articles found that women and minority populations were underrepresented in clinical trials. Some articles proposed solutions to improve clinical trial diversity; however, several did not comment on clinical trial diversity. Despite a growing emphasis on demographic diversity in research, certain populations continue to be underrepresented in clinical trials. There is a need to standardize the definition of diversity in clinical trials. Future research into effective enrollment approaches and appropriate reference standards could improve demographic diversity.

Intravenous perampanel as an alternative to the oral formulations in Japanese patients with epilepsy

OBJECTIVE

Perampanel is an oral anti-seizure medication, which is approved in Japan for focal-onset seizures, with/without focal to bilateral tonic-clonic seizures, as monotherapy/adjunctive therapy in patients aged 4 years and older. Treatment for generalized tonic-clonic seizures as adjunctive therapy in patients aged 12 years and older is approved as well. We evaluated the feasibility of intravenous (IV) administration of perampanel as an alternative to oral administration.

METHODS

Study 240 (NCT03754582) was an uncontrolled, open-label study of IV perampanel, conducted in 21 Japanese patients with epilepsy who received a stable dose of 8-12 mg/day of oral perampanel. Patients received 30-minute IV infusions at equivalent daily doses of oral perampanel for 4 days, then were switched back to oral perampanel. Safety, tolerability, plasma concentration, and maintenance of efficacy throughout the transition between IV and oral dosing of perampanel were assessed. As supportive data, a subgroup analysis was also conducted using data from healthy Japanese subjects (n = 18) who were enrolled in Study 050 (NCT03376997) investigating the pharmacokinetics and safety of IV perampanel in healthy subjects who received an IV infusion (30-, 60-, or 90-minute) of perampanel 12 mg and a single oral administration of perampanel 12-mg tablet.

RESULTS

In Study 240, the transition between 30-minute IV and oral perampanel dosing was associated with a ≤1.4-fold increase in the mean change in maximum observed concentration of perampanel. Seizure outcomes demonstrated no considerable changes in efficacy before, during, or after 30-minute IV dosing of perampanel. The safety profiles were similar between IV and oral formulations. In Study 050, the pharmacokinetics of 30- or 60-minute IV infusion of perampanel further support the interchangeability between oral and IV formulations in the Japanese subjects.

SIGNIFICANCE

These results support that 30-minute IV perampanel may be a potential short-term alternative to oral formulations for patients with epilepsy.

Initial therapeutic target attainment of perampanel in pediatric patients with epilepsy

Perampanel is a promising option for the treatment of pediatric epilepsy, but its plasma concentration varies among patients. This retrospective study aimed to investigate the initial target attainment of perampanel plasma concentration in pediatric patients with epilepsy in China. Inpatients admitted from January 2020 to December 2021 in a tertiary hospital were retrospectively included according to pre-set criteria. Demographic characteristics of patients and dosing strategies and therapeutic drug monitoring results were collected. A total of 137 pediatric patients (84 females and 53 males, aged from 0.6 to 16.4 years) were include for analysis. The perampanel concentrations varied greatly from 60 to 1,560 mg/L among patients, but 89.8% had suitable perampanel concentrations (100-1,000 ng/mL). The concomitant use of enzyme-inductive antiepileptic drugs (AEDs) was the only identified risk factor associated with target nonattainment (OR = 5.92, 95% confidence interval 1.68-20.9). Initial perampanel target attainment in pediatric patients is satisfactory. Routine therapeutic drug monitoring to achieved the suggested concentration range for these patients may be unnecessary, except for those receiving combined enzyme inductive AEDs.

Population Pharmacokinetic Analysis of Drug-Drug Interactions Between Perampanel and Carbamazepine Using Enzyme Induction Model in Epileptic Patients

BACKGROUND

Perampanel (PER) is an oral antiepileptic drug and its concomitant use with carbamazepine (CBZ) leads to decreased PER concentrations. However, the magnitude of its influence may vary, depending on the dynamics of the enzyme induction properties of CBZ. This study aimed to develop a population pharmacokinetic (PPK) model considering the dynamics of enzyme induction and evaluate the effect of CBZ on PER pharmacokinetics.

METHODS

We retrospectively collected data on patient background, laboratory tests, and prescribed drugs from electronic medical records. We developed 2 PPK models incorporating the effect of CBZ-mediated enzyme induction to describe time-concentration profiles of PER using the following different approaches: (1) treating the concomitant use of CBZ as a categorical covariate (empirical PPK model) and (2) incorporating the time-course of changes in the amount of enzyme by CBZ-mediated induction (semimechanistic PPK model). The bias and precision of the predictions were investigated by calculating the mean error, mean absolute error, and root mean squared error.

RESULTS

A total of 133 PER concentrations from 64 patients were available for PPK modelling. PPK analyses showed that the co-administration of CBZ increased the clearance of PER. Goodness-of-fit plots indicated a favorable description of the observed data and low bias. The mean error, mean absolute error, and root mean square error values based on the semimechanistic model were smaller than those obtained using the empirical PPK model for predicting PER concentrations in patients with CBZ.

CONCLUSIONS

We developed 2 PPK models to describe PER pharmacokinetics based on different approaches, using electronic medical record data. Our PPK models support the use of PER in clinical practice.

Population Pharmacokinetic Analysis of Perampanel in Portuguese Patients Diagnosed with Refractory Epilepsy

Perampanel is a promising antiepileptic drug (AED) for refractory epilepsy treatment due to its innovative mechanism of action. This study aimed to develop a population pharmacokinetic (PopPK) model to be further used in initial dose optimization of perampanel in patients diagnosed with refractory epilepsy. A total of seventy-two plasma concentrations of perampanel obtained from forty-four patients were analyzed through a population pharmacokinetic approach by means of nonlinear mixed effects modeling (NONMEM). A one-compartment model with first-order elimination best described the pharmacokinetic profiles of perampanel. Interpatient variability (IPV) was entered on clearance (CL), while the residual error (RE) was modeled as proportional. The presence of enzyme-inducing AEDs (EIAEDs) and body mass index (BMI) were found as significant covariates for CL and volume of distribution (V), respectively. The mean (relative standard error) estimates for CL and V of the final model were 0.419 L/h (5.56%) and 29.50 (6.41%), respectively. IPV was 30.84% and the proportional RE was 6.44%. Internal validation demonstrated an acceptable predictive performance of the final model. A reliable population pharmacokinetic model was successfully developed, and it is the first enrolling real-life adults diagnosed with refractory epilepsy.

Open-label study to investigate the safety and efficacy of adjunctive perampanel in pediatric patients (aged 4 to <12 years) with inadequately controlled focal-onset seizures: Japanese subgroup analysis

PURPOSE

To evaluate the safety and tolerability of adjunctive perampanel in a Japanese subpopulation of Study 311 (NCT02849626), which was a global, multicenter, open-label, single-arm study of children (aged 4 to <12 years) with inadequately controlled focal-onset seizures (FOS), with or without focal to bilateral tonic-clonic seizures (FBTCS) or generalized tonic-clonic seizures (GTCS).

METHODS

Study 311 comprised a Core Study, Extension A, and Extension B; this report focuses on the Japanese patient subgroup in the Core Study only. In the Core Study, Japanese patients (FOS only) received adjunctive perampanel ≤12 mg/day in a 23-week Treatment Phase. Endpoints included safety/tolerability (primary) and median percent change in seizure frequency per 28 days from baseline. Patients were stratified by age and concomitant enzyme-inducing anti-seizure medication (EIASM) use.

RESULTS

Of 65 enrolled Japanese patients, 56 completed the Core Study and nine withdrew. The most common reason for discontinuation was adverse events (AEs) (n = 4 [6.2%]). The mean (standard deviation) daily dose of perampanel in Japanese FOS patients was 5.8 (2.2) mg/day. During the Core Study, treatment-emergent AEs (TEAEs) were reported by 89% of Japanese patients, most commonly nasopharyngitis (28%) and somnolence (28%). The median percent reduction in seizure frequency per 28 days from baseline was 37% and the lower limit of the 95% CI was greater than 10.5%, satisfying the pre-defined efficacy criteria. Perampanel was effective regardless of age or concomitant EIASM use.

CONCLUSION

Perampanel as adjunctive therapy is generally safe, well-tolerated, and efficacious in Japanese children aged 4 to <12 years with FOS (with/without FBTCS).

A Single- and Multiple-Dose Pharmacokinetic Study of Oral Perampanel in Healthy Chinese Subjects

BACKGROUND AND OBJECTIVE

Perampanel is a once-daily oral anti-seizure medication indicated for focal-onset seizures and generalized tonic-clonic seizures. This study investigated the single- and multiple-dose pharmacokinetics of perampanel in healthy Chinese adults.

METHODS

Study 052 (NCT03424564) was a phase I, single-center, open-label, parallel-group study. In the single-dose part of the study, subjects received a single oral dose of perampanel 2, 4, or 8 mg. In the multiple-dose part, subjects received once-daily oral perampanel 2 mg on Days 1-7 and 4 mg on Days 8-21. Pharmacokinetic parameters were determined from perampanel plasma concentrations using non-compartmental analysis. Dose proportionality after single doses of perampanel was assessed. Safety and tolerability were evaluated.

RESULTS

In the single-dose part (N = 30), median time to reach maximum concentration (t_max) was 0.75-1.0 h, mean terminal elimination phase half-life (t_½) was 85.6-122 h, mean maximum observed concentration (C_max) was 77.9-276 ng/mL, and mean area under the concentration-time curve from time zero to time of the last quantifiable concentration (AUC_(0-t)) was 4070-15100 ng·h/mL. Single-dose pharmacokinetics were linear for perampanel 2-8 mg. In the multiple-dose part (N = 12), Day 21 steady-state (4 mg/day) parameters were median time at which the highest drug concentration occurs at steady state (t_ss,max), 1.25 h; mean t_½, 109 h; mean maximum observed concentration at steady state (C_ss,max), 453 ng/mL; and mean area under the concentration-time curve over the dosing interval on multiple dosing (AUC_{(0- τ)}), 7540 ng·h/mL. For single- and multiple-dose perampanel, the most common treatment-emergent adverse events were dizziness and somnolence.

CONCLUSIONS

Single- and multiple-dose pharmacokinetics of perampanel in healthy Chinese adults revealed rapid perampanel absorption, slow elimination, and a linear relationship with single perampanel doses of 2-8 mg. Findings were consistent with previous studies of perampanel pharmacokinetics in other ethnic/racial populations of healthy subjects. Single and multiple doses of perampanel were generally safe and well tolerated.

CLINICAL TRIAL REGISTRATION

NCT03424564; registered February 2018.

Safety evaluation of perampanel as monotherapy or first adjunctive therapy in patients with epilepsy

INTRODUCTION

There is a need for anti-seizure medications (ASMs) that are well tolerated and effective as monotherapy or first adjunctive therapy to reduce the need for adjunctive ASMs to treat newly diagnosed epilepsy, and to reduce the number of concomitant ASMs in patients with refractory epilepsy. Although the pivotal trials of perampanel evaluated its adjunctive use in patients with refractory seizures, open-label/real-world studies support its use in first/second-line settings.

AREAS COVERED

This paper reviews the pharmacology, efficacy, and safety/tolerability of perampanel, focusing on its use as monotherapy or first adjunctive therapy. The safety of perampanel in special populations and its safety/tolerability compared with that of other ASMs is also discussed.

EXPERT OPINION

Perampanel is a favorable candidate for initial or first adjunctive therapy due to its favorable efficacy and safety/tolerability as monotherapy and adjunctive therapy, its long half-life and ease of use, and its limited drug-drug interactions. The proposed mitigation strategies for managing the risk of serious psychiatric adverse events are appropriate patient selection, use of low doses, and slow titration. The growing body of evidence might shift current treatment strategies towards the early use of perampanel and its use at a low dose (4 mg/day).

Infection-Induced Elevated Plasma Perampanel in a Patient with Hemimegalencephaly

Perampanel is a noncompetitive, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid glutamate receptor antagonist. Herein, we report a case of increased perampanel plasma concentration and impaired consciousness triggered by an infection. The patient had refractory epilepsy associated with hemimegalencephaly. During adolescence, perampanel (maximum dose, 10 mg, oral), valproic acid, clobazam, and lacosamide were administered for seizure control. He was admitted to our hospital with high fever, impaired consciousness, and elevated perampanel plasma level (from 1,300 to 1,790 ng/mL), but with no increase in the concentration of other antiseizure medications. Further examinations (blood, cerebrospinal fluid, brain magnetic resonance images, and electroencephalogram) revealed no physical cause for impaired consciousness. After discontinuation of perampanel, his level of consciousness gradually improved. The pharmacokinetics of perampanel may be modified by both hemimegalencephaly and infection, resulting in an elevated plasma concentration of perampanel. This case underlines the importance of monitoring perampanel plasma concentration in patients with underlying brain disease who develop an infection.

Sustained seizure freedom with adjunctive perampanel in patients with convulsive seizures: Post hoc analysis of open-label extension studies 307 and 332

OBJECTIVE

Since increased mortality rates have been associated with convulsive seizures, it is important to achieve seizure control in these patients. Here, we report post hoc analyses to assess long-term seizure-freedom rates with adjunctive perampanel in patients (aged ≥ 12 years) with refractory focal to bilateral tonic-clonic seizures (FBTCS) or generalized tonic-clonic seizures (GTCS) who participated in open-label extension (OLEx) studies.

METHODS

Patients with focal-onset seizures, with/without FBTCS, who completed double-blind, Phase III Studies 304, 305, or 306 could enter OLEx Study 307 (16-week blinded Conversion; 256-week Maintenance). Patients with GTCS who completed the double-blind phase of Study 332 could enter the OLEx Phase (6-week blinded Conversion; 136-week Maintenance). Maximum perampanel dose: 12 mg/day. Seizure-freedom rates for up to 24 months were assessed in perampanel-treated patients who achieved seizure freedom during the double-blind studies to determine if their seizure-free status was maintained during the OLEx. In addition, to ensure any patients who only achieved seizure freedom during the OLEx were captured, seizure-freedom rates were also assessed in all patients who achieved and maintained a seizure-free status for a period of at least six consecutive months at any time during the double-blind and/or OLEx studies; some of these patients may have received placebo during the double-blind study but only their time on perampanel is included in the seizure-free analysis. Univariate and multivariate analyses were used to identify predictive factors for achieving seizure freedom for at least 6 months. Treatment-emergent adverse events (TEAEs) were assessed.

RESULTS

Overall, 53.8% (n = 42/78) of patients who received perampanel and were FBTCS free during the double-blind studies remained seizure free for up to 24 months during Study 307, and 31.6% (n = 6/19) of patients who were GTCS free during the double-blind phase of Study 332 remained seizure free for up to 24 months during the OLEx Phase. Over 40% (FBTCS, 41.5% [n = 197/475]; GTCS, 52.9% [n = 73/138]) of patients were seizure free for a period of at least six consecutive months. Multivariate analysis showed that the best predictors of achieving seizure freedom from FBTCS for at least 6 months were lower baseline seizure frequency (p = 0.0014) and absence of enzyme-inducing anti-seizure medications at baseline (p = 0.0056); multivariate analysis was not conducted for GTCS since only one variable was identified as a significant predictor of seizure freedom in the univariate analysis (lower baseline seizure frequency). Perampanel was generally well tolerated with no new safety signals identified. The most common TEAE was dizziness. For both seizure types, 10% or fewer seizure-free patients discontinued perampanel due to TEAEs.

CONCLUSIONS

These results suggest that adjunctive perampanel may be a suitable long-term treatment option for patients (aged ≥ 12 years) with convulsive seizures to achieve and maintain seizure freedom.

Utility and Safety of Perampanel in Pediatric FIRES and Other Drug-Resistant Epilepsies

Perampanel is a novel antiepileptic drug, which antagonises AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) glutamate receptor. We describe perampanel as an adjunctive treatment for FIRES (febrile infection-related epilepsy syndrome) and other drug-resistant epilepsies. A single-centre, observational, retrospective study involving 20 pediatric patients was conducted. Perampanel was started for three patients with FIRES, achieving seizure cessation in two patients within a day and on days 19 and 32 of illness. Doses used ranged from 4 to 12 mg/day, without any adverse effects reported or discontinuation of therapy. Responder-rate for other drug-resistant epilepsies is 25%. Median time to achieve ≥50% seizure reduction was 80 days (range: 26-326 days). Adverse effect reported in 47% of the patients includes central nervous system-related, and thrombocytopenia. Eight patients discontinued perampanel, because of ineffectiveness or adverse effects. The median time on perampanel before discontinuation was 179 days (range: 94-345 days). Perampanel may be of benefit in pediatrics FIRES and is of utility in other drug-resistant epilepsies.

Liquid chromatographic methods for determination of the new antiepileptic drugs stiripentol, retigabine, rufinamide and perampanel: A comprehensive and critical review

The new antiepileptic drugs perampanel, retigabine, rufinamide and stiripentol have been recently approved for different epilepsy types. Being them an innovation in the antiepileptics armamentarium, a lot of investigations regarding their pharmacological properties are yet to be performed. Besides, considering their broad anticonvulsant activities, an extension of their therapeutic indications may be worthy of investigation, especially regarding other seizure types as well as other central nervous system disorders. Although different liquid chromatographic (LC) methods coupled with ultraviolet, fluorescence, mass or tandem-mass spectrometry detection have already been developed for the determination of perampanel, retigabine, rufinamide and stiripentol, new and more cost-effective methods are yet required. Therefore, this review summarizes the main analytical aspects regarding the liquid chromatographic methods developed for the analysis of perampanel, retigabine (and its main active metabolite), rufinamide and stiripentol in biological samples and pharmaceutical dosage forms. Furthermore, the physicochemical and stability properties of the target compounds will also be addressed. Thus, this review gathers, for the first time, important background information on LC methods that have been developed and applied for the determination of perampanel, retigabine, rufinamide and stiripentol, which should be considered as a starting point if new (bio)analytical techniques are aimed to be implemented for these drugs.

Perampanel dosage in plasma samples: development and validation of a novel HPLC method with combined UV-Fluorescence detection

Therapeutic drug monitoring (TDM) is a recognized method to improve the quality of use of antiepileptic drugs, such as perampanel (PRP). It is the first compound in the class of selective non-competitive antagonists of AMPA receptors approved in 2012 in Europe and United States for adjunctive therapy of partial seizures. Although several studies have recently underlined that a general reference range for PRP plasmatic concentration might be difficult to propose, TDM of this drug is important in specific clinical situations, as hepatic or renal impairment or co-administration with enzyme-inducing antiepileptics. Several methods have been described in literature for the determination of PRP in different biological matrices, which include the use of liquid chromatography methods coupled with ultraviolet, fluorescence, mass or tandem-mass spectrometry detection. Here we describe the development and validation of a novel method for the measurement of PRP in plasma samples, based on a HPLC-UV/FL double detection approach and using ketoprofen as internal standard. PRP concentration in a small subset of plasma samples of treated patients was evaluated using both our approach and a commercially available CE-IVD LC-MS/MS method. The results obtained were compared, and confirmed the possibility to use our method as an alternative to LC-MS/MS in clinical routine.

A multivariable prediction model of a major treatment response for focal-onset seizures: A post-hoc analysis of Phase III trials of perampanel

OBJECTIVE

Although 50 % reduction in seizure frequency is a common efficacy endpoint in clinical trials of antiepileptic drugs (AEDs), 75 % or greater reductions may be required to improve patients' health-related quality of life. Identification of clinical factors that are associated with high responder rates may help to inform clinicians on which patients may optimally benefit from treatment. We evaluated potential predictive factors for achieving major treatment responses (≥75 % reduction in seizure frequency per 28 days from study baseline) in patients with drug-resistant focal-onset seizures, with/without focal to bilateral tonic-clonic (FBTC) seizures in perampanel trials designed for regulatory approval.

METHODS

Univariate analyses using logistic regression were performed using data from three double-blind, placebo-controlled Phase III studies of adjunctive perampanel (Studies 304 [NCT00699972], 305 [NCT00699582], 306 [NCT00700310]), and their open-label extension study (OLEx; Study 307 [NCT00735397]). For the double-blind studies, baseline seizure frequency, number of baseline AEDs, baseline seizure type, baseline concomitant enzyme-inducing AEDs (EIAEDs), baseline carbamazepine, lamotrigine, or valproic acid, age at diagnosis, time since diagnosis, etiology, and perampanel plasma concentration were included individually with study treatment. The same factors were included for the OLEx analysis except for plasma concentration and treatment. Variables found to be significant predictors for a major treatment response in univariate analyses were subsequently included in multivariable analyses using backwards and forwards selection.

RESULTS

In the double-blind studies, 175/1374 patients had a major response to placebo (n = 25) or perampanel (n = 150). The best predictors of a major treatment response in multivariable models with forwards and backwards selection were: the presence of FBTC seizures during baseline (P = 0.0002), higher perampanel plasma concentration (P < 0.0001), older age at diagnosis (P = 0.0024 and 0.0045, respectively), and lower baseline seizure frequency (P = 0.0364 and 0.0127, respectively). In the OLEx, 217/1090 patients had a major treatment response. The best predictors of a major treatment response in the final multivariable model, regardless of backwards or forwards selection, were a lower baseline seizure frequency (P = 0.0022), the absence of focal impaired awareness seizures during baseline (P = 0.0011), the presence of FBTC seizures during baseline (P = 0.0164), lower number(s) of baseline AEDs (P = 0.0002), the absence of EIAEDs during baseline (P = 0.0059), an older age at diagnosis (P = 0.0054), and absence of structural etiologies (P = 0.0138).

SIGNIFICANCE

These analyses of placebo-controlled and long-term extension trial data identified a number of potential predictive factors for patients with focal-onset seizures achieving a major treatment response. These factors may help guide clinicians when predicting a patient's response to treatment and optimizing individual treatment regimens.

Efficacy, safety, and tolerability of adjunctive perampanel in patients from China with focal seizures or generalized tonic-clonic seizures: Post hoc analysis of phase III double-blind and open-label extension studies

Aims

This post hoc analysis assessed the efficacy and safety/tolerability of adjunctive perampanel in patients from China (aged ≥12 years) with focal seizures (FS), with/without focal to bilateral tonic‐clonic seizures (FBTCS), or generalized tonic‐clonic seizures (GTCS).

Methods

Study centers in China were identified using data from five double‐blind, randomized, phase III studies of adjunctive perampanel (2‐12 mg/day) and their open‐label extensions (OLEx). Efficacy assessments included median percent reduction in seizure frequency per 28 days, and 50% and 75% responder and seizure‐freedom rates. Safety/tolerability assessments included monitoring of treatment‐emergent adverse events (TEAEs).

Results

Overall, 277 patients (placebo, n = 79; perampanel, n = 198) were included in the double‐blind safety analysis set. The full analysis set comprised 274 patients (FS, n = 238 [placebo, n = 60; perampanel, n = 178]; FBTCS, n = 120 [placebo, n = 31; perampanel, n = 89]; GTCS, n = 36 [placebo, n = 18; perampanel, n = 18]). Median percent reductions in seizure frequency for placebo vs perampanel were as follows: 16.6% vs 32.4% (FS; P < 0.05) and 39.1% vs 48.2% (FBTCS; not significant [NS]) at 4‐12 mg/day, and 37.9% vs 82.6% (GTCS; NS) at 8 mg/day; 50% responder rates were 31.7% vs 37.4% (FS; NS), 48.4% vs 51.9% (FBTCS; NS), and 33.3% vs 61.1% (GTCS; NS), respectively. Seizure‐freedom rates were 1.7% vs 9.2%, 16.1% vs 25.3%, and 16.7% vs 44.4%, respectively (all NS). Overall, 262 patients entered the OLEx (FS, n = 228; GTCS, n = 34). Perampanel was efficacious for up to four years for FS and FBTCS and up to two years for GTCS. Across the double‐blind and OLEx studies, TEAEs were reported in 65.7% and 81.3% of perampanel‐treated patients, respectively; the most common was dizziness. Efficacy and safety/tolerability outcomes were generally similar between Chinese and non‐Chinese patients.

Conclusion

Adjunctive perampanel (up to 12 mg/day) may be a suitable treatment for Chinese patients with FS, with/without FBTCS, or GTCS, with similar efficacy and safety/tolerability compared to non‐Chinese patients.

Changes in perampanel levels during de-induction: Simulations following carbamazepine discontinuation

Objective

To evaluate the time course of changes in perampanel levels when co‐administered with carbamazepine, and following carbamazepine discontinuation, using a physiologically based pharmacokinetic (PBPK) model.

Methods

The PBPK model was developed, verified using clinical PK data, and used to simulate the effect of abrupt discontinuation and down‐titration (75 mg twice daily [bid]/wk) of co‐administered carbamazepine 300 mg bid on the PK of perampanel once daily (qd). Perampanel dose tapering (8‐4 mg) and up‐titration (2‐6 mg) were simulated during abrupt carbamazepine 300 mg bid discontinuation to identify a titration schedule that minimizes changes in perampanel plasma concentrations.

Results

The PBPK model accurately reproduced perampanel plasma concentration‐time profiles from clinical studies in single‐ and multiple‐dose regimen simulations, including multiple‐dose carbamazepine co‐administration. The time course of return to pre‐induced perampanel levels occurred more slowly following carbamazepine down‐titration (~48 days after first down‐titration) vs abrupt discontinuation (~25 days). Perampanel dose tapering (8‐4 mg) at abrupt carbamazepine discontinuation produced minimal changes in steady‐state concentrations, which returned to the levels observed during carbamazepine co‐administration in ~15 days from the time of carbamazepine discontinuation. When perampanel was up‐titrated in the presence of carbamazepine, return to steady state occurred more slowly when carbamazepine was down‐titrated weekly (~45 days) vs abrupt discontinuation (~24 days).

Conclusion

This PBPK model simulated and predicted optimal perampanel dose tapering and up‐titration schedules for maintaining perampanel levels during conversion to monotherapy. These results may guide physicians when managing conversion from perampanel polytherapy with concomitant enzyme‐inducing anti‐seizure medications to monotherapy.

Efficacy and safety of perampanel monotherapy in patients with focal-onset seizures with newly diagnosed epilepsy or recurrence of epilepsy after a period of remission: The open-label Study 342 (FREEDOM Study)

Objective

Our study assessed perampanel monotherapy in patients (aged ≥12 years) with focal‐onset seizures (FOS) with or without focal to bilateral tonic‐clonic seizures (FBTCS) in Japan and South Korea.

Methods

Study 342 (NCT03201900; FREEDOM) is a single‐arm, open‐label, Phase III study. Patients initially received perampanel in a 32‐week 4‐mg/d Treatment Phase (6‐week Titration; 26‐week Maintenance Periods). If they experienced a seizure during the 4‐mg/d Maintenance Period, they could be up‐titrated to 8 mg/d across an additional 30‐week Treatment Phase (4‐week Titration; 26‐week Maintenance Periods). Primary endpoint was the seizure‐freedom rate during the Maintenance Period (4 mg/d and last evaluated dose [4 or 8 mg/d]). Secondary endpoints included time to first seizure onset and to withdrawal during Maintenance. Treatment‐emergent adverse events (TEAEs) were monitored.

Results

At data cutoff (February 28, 2019), 89 patients with FOS (84 [94.4%] with newly diagnosed epilepsy and 5 [5.6%] with recurrence of epilepsy after a period of remission) had received ≥1 perampanel dose; 16 patients discontinued during the 4‐mg/d Titration Period, meaning 73 patients entered the 4‐mg/d Maintenance Period and were included in the primary analysis set for efficacy. Seizure‐freedom rate in the 26‐week Maintenance Period was 46/73 (63.0%; 95% confidence interval [CI]: 50.9‐74.0) at 4 mg/d and 54/73 (74.0%; 95% CI: 62.4‐83.5) at 4 or 8 mg/d. Cumulative probability of seizure‐onset and withdrawal rates during Maintenance was 30.8% (95% CI: 21.5‐43.0) and 23.7% (95% CI: 15.4‐35.3) at 4 mg/d, and 18.2% (95% CI: 11.0‐29.3) and 23.3% (95% CI: 15.2‐34.8) at 4 or 8 mg/d. Perampanel was generally well tolerated, and the most common TEAE was dizziness.

Significance

Perampanel monotherapy (4 to 8 mg/d) was efficacious and consistent with the known safety profile up to 26 weeks in patients (≥12 years) with primarily newly diagnosed FOS with or without FBTCS.

Efficacy, safety, and tolerability of perampanel in Asian and non-Asian patients with epilepsy

People of different ethnic or racial backgrounds may experience variations in pharmacokinetic and pharmacodynamic responses to drug therapies. Our post hoc analysis evaluated the efficacy, safety, and tolerability of perampanel in Asian and non-Asian populations with refractory focal seizures with or without focal to bilateral tonic-clonic (FBTC) seizures. This analysis pooled data from 4 randomized, placebo-controlled, phase-3 studies involving patients aged ≥12 years who have focal seizures with or without FBTC seizures. Patients were receiving 2, 4, 8, or 12 mg perampanel (or placebo) by the end of a 6-week titration period and for a further 13 weeks during the maintenance phase. Efficacy endpoints included median percent change in seizure frequency per 28 days, and 50% and seizure-freedom responder rates relative to baseline. The median percent change in seizure frequency per 28 days from baseline was significantly greater than placebo for perampanel 8 and 12 mg (-31.1% and -38.1% change, respectively; each P < 0.0001) in the Asian population, and for perampanel 4, 8, and 12 mg (-21.1% [P = 0.0001], -26.3% [P < 0.0001], and -27.7% [P = 0.0001] change, respectively) in the non-Asian population. The 50% responder rate relative to baseline was significantly greater than placebo for perampanel 8 and 12 mg (40.1% and 43.8%, respectively; each P < 0.0001) in the Asian population, and for perampanel 4, 8, and 12 mg (29.4% [P = 0.0002], 32.8% [P < 0.0001] and 34.5% [P = 0.0001]), respectively, in the non-Asian population. Seizure-freedom rate among all patients was 4.9%-11.7% for perampanel 2, 4, 8, and 12 mg. The most frequently reported treatment-emergent adverse events (TEAEs) across both populations were dizziness, somnolence, irritability, headache, and fatigue. The most common psychiatric TEAEs were aggression and irritability. Perampanel demonstrated a favorable and similar risk-benefit profile in both Asian and non-Asian populations with refractory focal seizures.

Efficacy and safety of perampanel in generalized and focal to bilateral tonic-clonic seizures: A comparative study of Asian and non-Asian populations

Perampanel is an approved adjunctive treatment for focal seizures with or without focal to bilateral tonic-clonic (FBTC) seizures and generalized tonic-clonic (GTC) seizures. We compared efficacy and safety of perampanel vs placebo in Asian and non-Asian populations in a post hoc analysis of pooled data from 5 randomized phase 3 studies. Patients (≥12 years old) with focal + FBTC seizures received perampanel 2, 4, 8, or 12 mg or placebo; patients with GTC seizures received perampanel 8 mg or placebo (titration: 4-6 weeks; maintenance: 13 weeks). Efficacy endpoints included median percentage change in FBTC or GTC seizure frequency per 28 days and 50% responder rate relative to baseline. Median percentage change in FBTC seizure frequency was significantly greater for perampanel 8 and 12 mg than placebo in the Asian population (median difference from placebo: -30.32%, P = 0.0017; -30.06%, P = 0.0008, respectively) and perampanel 4, 8, and 12 mg in the non-Asian population (-35.07%, P = 0.0001; -37.78%, P < 0.0001; -34.53%, P < 0.0001, respectively). In both populations, median percentage change in GTC seizure frequency was significantly greater for perampanel 8 mg than placebo (median difference from placebo: Asian, -37.37%, P = 0.0139; non-Asian, -27.04%, P = 0.0006). The 50% responder rates were significantly greater than placebo for perampanel 8 and 12 mg for FBTC seizures (Asian: 58.0%, P = 0.0017 and 58.6%, P = 0.0013, respectively; non-Asian: 59.3%, P < 0.0001 and 54.3%, P = 0.0050, respectively) and perampanel 8 mg for GTC seizures (Asian: 57.6%, P = 0.0209; non-Asian: 68.8%, P = 0.0329). Pooled FBTC/GTC seizure data showed generally similar patterns of response to perampanel in both populations. The most frequent treatment-related adverse events were fatigue, irritability, dizziness, somnolence, and headache. Perampanel was effective, well tolerated, and can be considered a therapeutic option for FBTC/GTC seizures in Asian populations.

Efficacy and safety of adjunctive perampanel in adolescent patients with epilepsy: Post hoc analysis of six randomized studies

OBJECTIVE

This post hoc analysis of six randomized, double-blind, Phase II and III studies evaluated efficacy and safety of adjunctive perampanel (2-12 mg/day) in adolescent patients (aged ≥12 to ≤17 years) with uncontrolled partial-onset seizures, with or without secondarily generalized (SG) seizures, or primary generalized tonic-clonic (PGTC) seizures.

METHODS

Adolescent patients from Studies 304 (NCT00699972), 305 (NCT00699582), 306 (NCT00700310), 335 (NCT01618695), 235 (NCT01161524), and 332 (NCT01393743) were included. Efficacy assessments (split by seizure type) included median percent change in seizure frequency per 28 days from baseline and seizure-freedom rates. Safety assessments (all seizure types combined) included monitoring of treatment-emergent adverse events (TEAEs).

RESULTS

The Safety Analysis Set included 372 adolescent patients (placebo, n = 114; perampanel, n = 258); the Full Analysis Set included 346 patients with partial-onset seizures (placebo, n = 103; perampanel, n = 243), of whom 125 experienced SG seizures during baseline (placebo, n = 37; perampanel, n = 88), and 22 with PGTC seizures (placebo, n = 9; perampanel, n = 13). Compared with placebo, perampanel 8 and 12 mg/day conferred greater median percent reductions in seizure frequency per 28 days for partial-onset seizures (18.0% vs 35.9% and 53.8% [both P < 0.01]) and SG seizures (24.4% vs 72.8% [P < 0.001] and 57.8% [P < 0.01]), and greater seizure-freedom rates (partial-onset: 7.8% vs 13.2% and 11.8% [not statistically significant]; SG: 8.1% vs 40.7% [P < 0.001] and 41.7% [P < 0.01]). For PGTC seizures, and compared with placebo, perampanel 8 mg/day was also associated with greater median percent reductions in seizure frequency per 28 days (29.8% vs 88.0%) and greater seizure-freedom rates (11.1% vs 23.1%). Treatment-emergent adverse events were reported in 76 (66.7%) placebo- and 192 (74.4%) perampanel-treated patients (most common: dizziness, somnolence, headache, and nasopharyngitis). Serious TEAEs occurred in 5 (4.4%) placebo- and 11 (4.3%) perampanel-treated patients.

CONCLUSIONS

Adjunctive perampanel was efficacious and generally well tolerated in adolescent patients with partial-onset, SG, or PGTC seizures and represents a potentially beneficial treatment option for adolescents with uncontrolled epilepsy.

Efficacy and serum concentrations of perampanel for treatment of drug-resistant epilepsy in children, adolescents, and young adults: comparison of patients younger and older than 12 years

PURPOSE

Perampanel (PER) is a selective, non-competitive antagonist of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor. In Japan, PER is approved for patients with epilepsy who are at least 12 years old for the adjunctive treatment of primary generalised tonic-clonic seizures and partial-onset seizures (with or without secondary generalization). We surveyed the efficacy, adverse effects, and serum concentrations of PER, focusing especially on patients younger than 12 years of age.

METHODS

We retrospectively surveyed the clinical information of patients treated with PER and assessed the efficacy at 6 months after treatment initiation. We compared efficacy, adverse effects, and serum concentration in patients younger or older than 12 years of age. Responders were defined as those who experienced a ≥50% seizure reduction.

RESULTS

Eighty-four patients were enrolled. The average age of the younger group was 7.1 ± 3.3 (standard deviation) years compared to 16.4 ± 3.7 years in the older group. The responder rate was 42.9% (36/84). The responder rate did not differ between the two age groups (<12 years, 20/44, 45.4%; >12 years, 16/40, 40.0%; p = 0.78). The younger age group had a significantly lower concentration-to-dose (CD) ratio than the older age group (<12 years, 1849.8 ± 2209.3; >12 years, 3076.3 ± 3352.2, p = 0.02). Treatment-emergent adverse events (TEAEs) were observed in 22.6% (19/84) of patients, with the most common being somnolence (8/84, 9.5%).

CONCLUSION

PER may be an alternative to treat seizures in paediatric drug-resistant epilepsy. Serum concentrations of PER might be lower in patients younger than 12 years than in older patients.

A post hoc analysis of the long-term safety and efficacy of perampanel in Asian patients with epilepsy

This post hoc analysis assessed the long-term safety, tolerability, and efficacy of perampanel in Asian patients with refractory focal seizures; an additional analysis assessed the effect of perampanel on focal impaired awareness seizures (FIAS) with focal to bilateral tonic-clonic (FBTC) seizures. In this subanalysis, data from Asian patients ≥12 years of age who had focal seizures with FBTC seizures despite taking one to 3 concomitant antiepileptic drugs at baseline, and who had entered either the long-term extension phase of 3 phase-3 perampanel trials (study 307) or the 10-week extension phase of study 335, were analyzed for the effect of perampanel on duration of exposure, safety, and seizure outcomes. Of 874 Asian patients included in the analysis, 205 had previously received placebo during the double-blind phase-3 trials and 669 had previously received perampanel 2-12 mg/day; 313 had FIAS with FBTC seizures at core study baseline. The median duration of exposure to perampanel was 385.0 days, and the retention rate at one year was 62.6%. Overall, during the first 52 weeks of perampanel treatment, 777 patients (88.9%) had treatment-emergent adverse events (TEAEs), most of which were mild to moderate in severity. The most frequent TEAEs were dizziness (47.1%), somnolence (22.3%), and nasopharyngitis (17.4%). During the first 52 weeks of perampanel treatment, median percent change in seizure frequency per 28 days from pre-perampanel baseline for all focal seizures was -28.1%, and -51.7% for FIAS with FBTC seizures. The 50% responder rate relative to pre-perampanel baseline for all focal seizures was 33.8%, and 51.1% for FIAS with FBTC seizures. Long-term treatment with perampanel in Asian patients had safety, tolerability, and efficacy similar to that of the global population in the phase-3 trials and extension study 307. The safety profile and response rate suggest benefit for an Asian population of patients with refractory epilepsy.

An Evidence-Based Review On The Use Of Perampanel For The Treatment Of Focal-Onset Seizures In Pediatric Patients

Perampanel, a non-competitive AMPA receptor antagonist, is a once-daily oral antiepileptic drug approved for the treatment of focal seizures and primary generalized tonic-clonic seizures in children 12 years of age and over. We conducted a systematic review of the data on perampanel in children and adolescents with focal-onset seizures. We found 21 published papers on the pediatric use of perampanel for focal-onset seizures, including 9 papers on clinical trials and ancillary studies of these trials, of which 2 focused on pharmacokinetics, 1 was a meta-analysis, and 9 were real-life studies (1 was prospective). Perampanel, as an adjunctive treatment for uncontrolled focal-onset seizures, results in an improvement of seizure control with a generally good safety profile. Evidence-based data are currently available for children 12 years of age and over. Higher amounts of perampanel might be required in patients taking enzyme-inducing antiepileptic drugs. The most common adverse events are somnolence, dizziness and behavioral adverse events. The latter seems more frequent in adolescents than in adults and in adolescents with preexisting behavioral comorbidities. Current studies did not identify any short-term impact of perampanel on cognitive functions. Its long half-life allows once-daily administration. Real-life studies further established that a decrease of the dose frequently resolves adverse events, as demonstrated in pivotal studies. Pharmacokinetic and safety studies are still ongoing in the younger population, down to 4 years of age, in order to apply for approval in this age group.

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.