Plasma concentration and clinical effects of perampanel—The Kork experience

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

INTRODUCTION

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

MATERIALS AND METHODS

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

RESULTS

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

DISCUSSION

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

CONCLUSION

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

Cenobamate Plasma Levels in Patients with Epilepsy: Correlation with Efficacy and Tolerability?

Objective: Cenobamate is approved by the European Medicine Agency for the treatment of adult patients with epilepsy (PWEs) with ongoing focal-onset seizures despite appropriate treatment with at least two established antiseizure medications. Pivotal trials and post-marketing real-world observational studies suggest high efficacy with unusually high seizure-free rates. The authors sought to investigate the plasma levels of cenobamate under steady-state conditions in seizure-free versus non-responding PWEs, and in PWEs who experienced adverse events versus those who did not. Methods: Blood samples were collected from adult PWEs who were treated with adjunct cenobamate under steady-state conditions. Daily doses, concomitant medications, efficacy, and tolerability were assessed. The plasma cenobamate levels of seizure-free versus non-responding PWEs and between PWEs with and those without clinical adverse events were compared. Results: Samples from 101 PWEs were included. Thirty-six PWEs were seizure-free and 65 were non-responders. In 31 PWEs, adverse events were apparent, whereas in the remaining 70, no tolerability issues were reported. A linear correlation was found between the daily doses (range: 100 mg-400 mg) and the plasma levels (3.8 mg/L-54.6 mg/L). Neither the daily doses nor the plasma levels differed significantly between the investigated subgroups. The main reason for this result was that the individual therapeutic ranges varied widely: seizure freedom and adverse effects were observed alongside low doses and plasma levels in some PWEs. Conversely, there were examples of PWEs who did not respond or who reported no tolerability issues at high doses or plasma levels. Conclusions: To evaluate the individual therapeutic range and to better understand the influence of other drugs in cases where concomitant medications are used, the therapeutic drug monitoring of cenobamate may be useful. A general therapeutic range cannot be defined.

Value of drug level concentrations of brivaracetam, lacosamide, and perampanel in care of people with epilepsy

OBJECTIVE

The aim of this study was to determine whether clinical efficacy and reported adverse effects (AEs) of the newer antiseizure medications (ASMs) brivaracetam (BRV), lacosamide (LCM), and perampanel (PER) have been associated with plasma levels of these ASMs. We also investigated whether plasma levels outside the reference range has led to dose adjustments.

METHODS

Plasma levels of 300 people with epilepsy (PWE) seen at our tertiary epilepsy center were determined by liquid chromatography-tandem mass spectrometry. PWE received BRV (n = 100), LCM (n = 100), or PER (n = 100), in most cases in polytherapy. Demographic and clinical data were retrospectively analyzed and related to plasma levels. Clinical efficacy of BRV, LCM, or PER was assessed retrospectively by comparing seizure frequency at the time of current blood draw with seizure frequency at the time of first administration. AEs were also recorded and, if reported, compared retrospectively with the time of first administration.

RESULTS

No significant associations were found between plasma levels of BRV, LCM, or PER and seizure freedom (BRV, p = 1.000; LCM, p = .243; PER, p = .113) or responder status (BRV, p = .118; LCM, p = .478; PER, p = .069) at presentation. There was also no pattern between plasma levels and the occurrence of AEs. In the majority of cases, drug levels outside the reference ranges have not led to adjustments in the daily doses of BRV (93.5%), LCM (93.9%), or PER (89.1%).

SIGNIFICANCE

Plasma levels at a given time point did not allow conclusions to be drawn about seizure control or the occurrence of AEs. Our findings indicate that efficacy and tolerability cannot be predicted based on averaged data from a single plasma measurement due to high interindividual variability. Instead, individual reference values should be established when sufficient clinical data are available, in line with the 2008 International League Against Epilepsy position paper on therapeutic drug monitoring.

Effectiveness and safety of mono- and add-on perampanel in pediatric patients with epilepsy: Experience from a single-center retrospective study

OBJECTIVE

To evaluate the effectiveness and safety of perampanel (PER) monotherapy (MT) or add-on therapy (AT) in Chinese children with epilepsy, as well as to evaluate the data from routine therapeutic drug monitoring (TDM) of PER for these pediatric patients.

METHODS

This retrospective and observational study was carried out on children with epilepsy (n = 340) from 2020 to 2022 at the Children's Hospital of Nanjing Medical University. Outcome measures were the responder rate (50% or greater seizure reduction), long-term efficacy, and tolerability (number and types of adverse events) in MT and AT groups. Concentrations of plasma PER obtained from these patients, if available, were analyzed too.

RESULTS

A total of 279 patients achieved at least 3 months of therapy, and 58.1% responded to PER therapy. 53 of the responders were seizure-free (32.7%). The retention rate dropped from 88.0% at 3 months to 40.6% at 12 months after treatment. Patients with MT achieved better seizure control than those with AT (P < 0.001). Intriguingly, PER exerted a very weak effect on patients who took more than 2 ASMs or were diagnosed with drug-resistant epilepsy. There were no significant differences in tolerability between the two groups. In addition, 179 patients were routinely monitored for PER, and the trough concentrations (C0 ) for these patients ranged from 30.0 to 992.0 ng/mL. However, no significant difference in C0 was observed between responders and nonresponders (333 ng/mL vs 325.5 ng/mL, P = 0.264).

SIGNIFICANCE

This study provides effectiveness and safety data on Chinese children with epilepsy treated with PER either as MT or as AT. The efficacy of patients receiving MT was much better than cases administered with more than 2 ASMs or diagnosed with drug-resistant epilepsy. In addition, no association was found between the plasma PER concentration and efficacy or safety.

PLAIN LANGUAGE SUMMARY

The study reports the effects of perampanel on seizures and adverse effects in Chinese patients with epilepsy younger than 18 years. Seizures decreased in 58.1% of patients (responders); in a third of these responders, seizures stopped. After treatment was started, 88% of patients were still on perampanel at 3 months and 40.6% at 12 months. People who were treated with perampanel only were more likely to respond than those who received perampanel and other antiseizure treatments, although perampanel was tolerated equally well in these groups. Plasma perampanel concentration did not predict seizure response or adverse effects.

Long-term efficacy and safety of perampanel as an add-on therapy in patients with epilepsy

BACKGROUND

Perampanel (PER) is a newly developed amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor antagonist that has been globally approved for the treatment of both focal and generalized seizures. The efficacy and safety of PER have only been reported over short periods of treatment so far. This study aims to clarify the long-term efficacy and safety of PER as an add-on therapy.

METHOD

This retrospective observational study investigated 176 epilepsy patients who received PER as add-on medical therapy in two Japanese epilepsy centers between June 2016 and July 2022. The adherence, seizure frequency, and plasma concentration of PER were evaluated at three time points: 6 months, 12 months, and 24 months or longer after the start of adjunctive PER treatment.

RESULTS

112 patients undergoing PER treatment were evaluated at 6 months, 86 were evaluated at 12 months, and 52 were evaluated at 24 months or longer. Overall, 42.9 % (48/112), 45.4 % (40/86), and 44.2 % (23/52) of the patients were seizure-free at 6, 12, and 24 months or longer, respectively. The rate of PER tolerance was 78.3 %, 69.9 %, and 54.7 % at 6, 12, and 24 months or longer, respectively. At the latest timepoint, the seizure-free group was taking a significantly lower dose of PER than the seizure-remnant group, and the number of anti-seizure medications (ASMs) was associated with seizure outcomes. In addition, the seizure-free rate was significantly higher in patients who received PER as a first add-on than in those who received it as a late add-on. No significant difference was found in the plasma concentration of PER between the seizure-free and seizure-remnant groups at 24 months or longer. Among the patients receiving PER at dose of 2 mg, however, the plasma concentrations were significantly higher in the seizure-free group than in the seizure-remnant group (282.7 ± 109.8 μg/ml vs 94.7 ± 54.9 μg/ml, p = 0.0024).

CONCLUSION

This long-term retrospective observational study provides evidence of the efficacy and safety of PER over 2 years treatment period in Japan. Notably, patients who started on PER as the first add-on showed a better seizure outcome than those who received it as a late add-on over the long term. Measured plasma concentrations may provide valuable guidance for the management of patients. Higher plasma concentration at low dose PER may suggest the better seizure control.

Therapeutic drug monitoring of perampanel: Clinical utility and impact of co-medication on pharmacokinetic variability

Background

Perampanel (PER) is a newly developed antiseizure medication (ASM). This study aimed to determine the utilization of therapeutic drug monitoring (TDM) for PER in a real-world clinical setting and investigate the influence of concomitant use of ASMs on the plasma concentration profile of PER.

Method

We analyzed data from the Chang Gung Research Database, which is the largest multi-institutional electronic medical records database in Taiwan. The main outcomes were the comparisons of PER plasma concentration and the ratio of concentration to the weight-adjusted dose (C/D; [ng/mL]/[mg/kg/d]) among patients received TDM of different clinical indication and among different ASM co-medication subgroups.

Results

Overall, 88 plasma samples were collected from 66 epilepsy patients treated with PER. The majority of patients (77.3 %) underwent PER TDM owing to poorly controlled seizures. There was a trend toward a higher plasma concentration and C/D ratio in those suspected of having PER toxicity owing to adverse events than of other indications. The PER concentration exhibited dose linearity. The mean PER plasma concentrations in patients co-medicated with enzyme-inducing ASMs were significantly lower than those in the patients who were not prescribed enzyme-inducing or enzyme-inhibiting ASMs, and co-medication with carbamazepine (CBZ) resulted in a significant reduction in the PER concentration.

Conclusion

PER concentration exhibited a linear regression relationship with PER dose, and the plasma concentration of the drug was highly susceptible to the drug's interactions with enzyme-inducing ASMs. TDM with clear indication could help determine the influence of ASMs used concomitantly on PER concentrations and guide clinical adjustments.

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.

Efficacy and Safety of Five Broad-Spectrum Antiseizure Medications for Adjunctive Treatment of Refractory Epilepsy: A Systematic Review and Network Meta-analysis

BACKGROUND

Overall, up to one-third of epilepsy patients have drug-resistant epilepsy. However, there was previously no meta-analysis to support the guidelines for broad-spectrum antiseizure medication selection for the adjunctive treatment of refractory epilepsy. In the present meta-analysis, we assessed the efficacy and safety of three second-generation broad-spectrum antiseizure medications, lamotrigine (LTG), levetiracetam (LEV), and topiramate (TPM), and two third-generation broad-spectrum antiseizure medications, perampanel (PER) and lacosamide (LCM), for the adjunctive treatment of refractory epilepsy.

METHODS

We systematically searched PubMed, Embase, and CENTRAL from inception to July 15, 2022. The studies included in the meta-analysis were required to meet the following criteria: (1) be randomized, double-blind clinical trials; (2) include patients aged >2 years with a clinical diagnosis of drug-resistant epilepsy; (3) have at least 8 weeks for the treatment period excluding the titration phase; and (4) report the outcomes of seizure response, seizure freedom and the withdrawal rate due to treatment-emergent adverse effects. Data were extracted, and the risk of bias for each study was assessed by two authors independently using RoB2 tools. We performed the network meta-analysis for each outcome through a group of programs in the mvmeta and network packages in Stata. Relative odds ratios with 95% confidence intervals were calculated as the result of the analyses. The surface under the cumulative ranking curve (SUCRA) and mean ranks were used to rank these treatments.

RESULTS

Forty-two randomized controlled trials (RCTs) (LTG-placebo: n = 6, LEV-placebo: n = 13, TPM-placebo: n = 9, PER-placebo: n = 6, LCM-placebo: n = 7, LEV-TPM: n = 1) with 10257 participants (LTG = 569, LEV = 1626, TPM = 701, PER = 1734, LCM = 1908, placebo = 3719) were included. Levetiracetam had subequal efficacy in 50 % seizure frequency reduction to TPM [odds ratio (OR) 1.00, 95% confidence interval (CI) 0.73-1.38], and LEV had a higher rate of ≥ 50% seizure frequency reduction than LCM (OR 1.49, 95% CI 1.11-2.01) and PER (OR 1.68, 95% CI 1.24-2.29). Levetiracetam was also related to a higher proportion of seizure freedom participants than TPM (OR 1.87, 95% CI 1.20-2.89), PER (OR 2.23, 95% CI 1.12-4.43), and LCM (OR 2.97, 95% CI 1.46-6.05). In addition, LEV was associated with a lower risk of experiencing at least one treatment-emergent adverse event (TEAE) than PER (OR 0.63, 95% CI 0.46-0.85) and TPM (OR 0.51, 95 % CI 0.36-0.72) and a lower proportion of patients experiencing TEAEs leading to discontinuation than PER (OR 0.51, 95% CI 0.27-0.97) and TPM (OR 0.50, 95 % CI 0.27-0.93).

CONCLUSIONS

Third-generation drugs (PER and LCM) had no advantages in terms of efficacy and safety for adjunctive treatment of refractory epilepsy compared with several second-generation drugs (LEV and LTG). Levetiracetam was the priority choice for adjunctive treatment of refractory epilepsy. Perampanel and LCM had no advantages in terms of efficacy and safety among the five drugs.

REGISTRATION

PROSPERO registration number, CRD42022344153; last edited on December 23, 2022.

Perampanel's forgiveness factor in a variable medication adherence paradigm in a rat model of chronic epilepsy

BACKGROUND

Poor medication adherence contributes to increased morbidity and mortality in patients with epilepsy and may be under-addressed in clinical practice. Ethical concerns make it impossible to study the impact of medication nonadherence in clinical trials, but our previous work emphasizes the importance of using preclinical approaches to address these questions. With over 30 clinically available antiseizure medicines (ASM's), it remains an important question to understand the relationship between poor adherence and seizure incidence across mechanistically distinct ASM's, including the broad-spectrum ASM, perampanel (PER).

METHODS

We formulated PER into chow pellets to deliver to rats in a 100% fully adherent or 50% variable nonadherent paradigm via our novel automated medication-in-food delivery system. Chronic oral dosing was initiated in male rats with chronic epilepsy while monitoring 24/7 for videoEEG evidence of seizures during a 4-week placebo baseline and 4-week treatment phase. PER concentrations were monitored in plasma at 1-week intervals and correlated with degree of seizure control. The relationship between missed doses and extended patterns of nonadherence were correlated with breakthrough seizures.

RESULTS

Fully adherent rats demonstrated a median reduction in seizure frequency of 50%, whereas nonadherent rats had a median increase of 54%. Plasma concentrations of PER were stable over the 4-week treatment period in both fully adherent and nonadherent groups, with levels being twice as high in fully adherent animals. There was no correlation between a single missed dose or series of missed doses and the incidence of breakthrough seizures. However, those animals in the nonadherent group that received PER for every meal during a 24-h period had a reduced likelihood of seizure incidence.

CONCLUSIONS

If our preclinical data is supported in the clinic, PER's favorable pharmacokinetic profile in humans, combined with a lowered risk of breakthrough seizures suggests that it may provide a certain forgiveness factor if a dose is missed within a 24-h window.

Analytical and Clinical Validation of Assays for Volumetric Absorptive Microsampling (VAMS) of Drugs in Different Blood Matrices: A Literature Review

Volumetric absorptive microsampling (VAMS) is the newest and most promising sample-collection technique for quantitatively analyzing drugs, especially for routine therapeutic drug monitoring (TDM) and pharmacokinetic studies. This technique uses an absorbent white tip to absorb a fixed volume of a sample (10-50 µL) within a few seconds (2-4 s), is more flexible, practical, and more straightforward to be applied in the field, and is probably more cost-effective than conventional venous sampling (CVS). After optimization and validation of an analytical method of a drug taken by VAMS, a clinical validation study is needed to show that the results by VAMS can substitute what is gained from CVS and to justify implementation in routine practice. This narrative review aimed to assess and present studies about optimization and analytical validation of assays for drugs taken by VAMS, considering their physicochemical drug properties, extraction conditions, validation results, and studies on clinical validation of VAMS compared to CVS. The review revealed that the bio-analysis of many drugs taken with the VAMS technique was optimized and validated. However, only a few clinical validation studies have been performed so far. All drugs that underwent a clinical validation study demonstrated good agreement between the two techniques (VAMS and CVS), but only by Bland-Altman analysis. Only for tacrolimus and mycophenolic acid were three measurements of agreement evaluated. Therefore, VAMS can be considered an alternative to CVS in routine practice, especially for tacrolimus and mycophenolic acid. Still, more extensive clinical validation studies need to be performed for other drugs.

Therapeutic Salivary Monitoring of Perampanel in Patients with Epilepsy Using a Volumetric Absorptive Microsampling Technique

The objective of this study was to validate a novel assay using the volumetric absorptive microsampling (VAMS) technique combined with liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) for the determination of the antiseizure medication perampanel in saliva and its clinical applicability in patients with epilepsy. VAMS tips were loaded with 30 μL of saliva and dried for 60 min. Analytes were extracted with methanol. The supernatant was evaporated under a gentle stream of nitrogen and reconstituted with 60 μL of methanol. Separation and quantification were achieved on a monolithic column connected to a mass spectrometer. Calibration curves were linear between 0.5 and 300 ng/mL. Intra- and inter-day accuracy was within 85.6-103.2% and intra-day and inter-day precision did not exceed 12.1%. Perampanel was stable in samples collected by VAMS and stored under different storage conditions. The VAMS-LC-MS/MS method was validated according to internationally accepted criteria and tested in patients with epilepsy who were receiving a combination of perampanel and other antiseizure medications. The method showed adequate bioanalytical performances, holding great potential as an alternative strategy to support domiciliary TDM in patients with epilepsy treated with perampanel according to the simplicity of sample collection.

Therapeutic drug monitoring of perampanel in children diagnosed with epilepsy: Focus on influencing factors on the plasma concentration-to-dose ratio

OBJECTIVE

This study aimed to investigate the efficacy and tolerability of perampanel (PER) therapy and to optimize a specific plasma reference range for PER in children. Another major aim was to evaluate the potential determinators of PER concentration.

METHODS

Concentrations obtained from 80 children were analyzed for routine therapeutic drug monitoring (TDM) between 2021 and 2022. We retrospectively reviewed the clinical data of these patients and assessed the efficacy at 3 months after treatment initiation. Trough concentration-to-dose ratio (C₀ /Dose ratio) of PER was compared among patients on various potential influencing factors.

RESULTS

A 3-month PER therapy produced a ≥50% reduction in seizure frequency in 58.8% of patients. Twelve patients reported at least one adverse effect (AE), mainly dizziness. The monitoring data showed that the median C₀ was 325.5 ng/mL. Under maintenance dosages, approximately 75% of the C₀ values were 180.0-610.0 ng/mL. The C₀ /Dose ratio in patients aged 1 to <4 was significantly lower by twofold than in those aged 4 to ≤12 years (P = 0.001). Enzyme-inducing ASMs (EIASMs) decreased the C₀ /Dose ratio of PER by 25.9% (P = 0.165). In addition, seizure frequency reduction in responders was achieved at a median PER C₀ value of 357 ng/mL, which was similar to the value of 314 ng/mL found in nonresponders (P = 0.288). No significant difference was found in PER C₀ values between patients with and without AEs (P = 0.082).

SIGNIFICANCE

In this study, PER treatment showed acceptable efficacy and tolerance in Chinese children with epilepsy. Contributing factors like age to variable C₀ /Dose ratios were identified, and complex PER-ASMs interactions were observed. Notably, the reference range, that is, 180.0-610.0 ng/mL, for routine PER monitoring may be more applicable for them. Routine TDM should be considered a positive attempt to manage the effectiveness and safety of PER.

Effectiveness of perampanel in the treatment of pediatric patients with focal epilepsy and ESES: A single-center retrospective study

Objective: To investigate the therapeutic effect and influencing factors of perampanel (PER) on electrical status epilepticus during sleep (ESES).

Methods: We retrospectively analyzed the clinical data of pediatric patients with focal epilepsy and ESES who were treated at the Epilepsy Center of Shengjing Hospital of China Medical University between January 2016 and March 2022. Changes in the spike wave index (SWI) after 24 weeks of PER add-on treatment were compared. Kaplan‒Meier survival analysis, the log-rank test and multivariate Cox regression analysis were performed.

Results: A total of 54 pediatric patients met the inclusion criteria, including 33 males and 21 females. The mean age at the diagnosis of epilepsy was 6.41 ± 2.14 years and at ESES diagnosis was 7.58 ± 2.40 years. The mean ESES duration before add-on PER was 25.31 ± 15.12 months. The mean age of the patients at add-on PER initiation was 9.69 ± 2.12 years. The ESES resolved in 29 children after 6 months of PER add-on treatment, and the response rate was 53.7%. Univariate analysis with the log-rank test showed that the therapeutic effect of PER differed according to the age at ESES diagnosis and ESES duration before add-on PER treatment. Multivariate Cox regression analysis showed that only ESES duration before PER administration was a risk factor for PER treatment failure, and the other factors had no effect on the therapeutic effect.

Conclusion: PER add-on treatment has a good therapeutic effect on ESES and can be used as an alternative to corticosteroid and benzodiazepines. The therapeutic effect of PER add-on treatment was not related to the dose. A longer ESES duration results in a worse therapeutic effect. Therefore, more aggressive treatment measures should be implemented for ESES.

The real-world effectiveness and safety of perampanel in Europe: A scoping review

In order to characterize the real-world effectiveness and safety of perampanel during clinical use in Europe, we conducted a structured literature search and scoping review of real-world studies conducted in Europe in adolescents (aged ≥ 12 years) or adults who were prescribed perampanel for focal epilepsy or primary generalized tonic-clonic seizures in the context of idiopathic generalized epilepsy, published between January 2016 and July 2021. We identified 29 relevant studies (20 retrospective and 9 prospective) in 3608 patients; median study duration was 12 months. Most patients (76.1%) were receiving two or more antiseizure drugs (ASDs) when perampanel was initiated. The maintenance perampanel dose ranged from 2 to 16 mg/day (most commonly 6 mg/day). Retention rate at 12 months ranged from 46% to 90.5% (median 71.1%). The proportion of patients who were free of seizures during perampanel ranged from 1.8% to 84.6%, but were consistently below 20% in studies where patients had received an average of ≥5 prior ASDs and above 20% where patients had received an average of <5 prior ASDs. The proportion of patients who achieved ≥50% reduction in seizures during perampanel ranged from 20.0% to 85.7%. Across all studies, the incidence of adverse events (AEs) ranged from 18.2% to 67.4% (median 37.1%) and discontinuation due to AEs from 6.2% to 56% (median 12.5%). Discontinuation rates tended to be higher in UK studies than in studies from Italy or Spain. The most commonly reported individual AEs were dizziness/vertigo (median incidence 13.7%), somnolence (median 11.9%), aggression (median 9.8%), irritability (median 9.1%), and cognitive deficits (median 7.0%). There was no relationship between the overall rate of AEs and perampanel dose, perampanel plasma levels, or number of concomitant medications. Our global overview of European observational studies with perampanel provides evidence that this agent is effective and safe in clinical practice in a range of countries, patients, and settings.

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.

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

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

Clinical effects and outcomes of perampanel overdoses reported to U.S. poison centers

INTRODUCTION

Perampanel is indicated for partial onset seizures in children and adults. The mechanism is unique among antiepileptic agents as it inhibits glutamate activity on AMPA receptors. Currently, there are few published case reports describing overdose.

METHODS

This is a retrospective observational study of all single substance perampanel ingestions from January 2014 to December 2019 reported to the national poison data system (NPDS). The primary outcome is to describe the clinical effects of perampanel exposures. Secondary outcomes include evaluation of management and investigation of a dose-effect relationship for the purpose of triaging acute unintentional exposures.

RESULTS

A total of 138 exposures were reported to NPDS since the release of the agent. Median age was 20 years (IQR 10-38) with 68 (49.3%) males. The reason for exposure was most commonly therapeutic error (80, 58.0%), followed by exploratory ingestion (24, 17.4%), and suicidal ingestion (14, 10.1%). A total of six (4.3%) patients developed major effects, 20 (14.5%) moderate, 32 (23.2%) minor effects and 22 (15.9%) no effect. An additional 54 (39.1%) cases were not followed. Almost half of cases were managed at home. Of those that were in a healthcare facility (HCF) (n = 72), most were treated/evaluated and released (31, 43.1%), followed by admission to a non-critical care unit (20, 27.8%), and critical care unit (13, 18.1%). Most frequently reported symptoms were drowsiness (27, 19.6%), agitation (20, 14.5%), ataxia (13, 9.4%), and confusion (12, 8.7%). The most common therapies provided in a HCF were intravenous fluids (22,30.6%), followed by benzodiazepines (14, 19.4%), then other types of sedation (9, 12.5%). There were too few cases to determine a dose cut off for triaging.

CONCLUSIONS

While drowsiness, agitation, ataxia, and confusion were the most often reported symptoms, close to 19% developed moderate/major effects and almost 4% of patients received potentially life-saving interventions.

Effect and tolerability of perampanel in patients with drug-resistant epilepsy

OBJECTIVE

Perampanel is one of the most recently approved antiseizure medications. The aim of the present study was to assess clinical efficacy and tolerability, in combination with pharmacokinetic variability, of perampanel treatment in patients at a tertiary referral center for epilepsy.

METHODS

We performed a retrospective observational study of patients given perampanel as adjunctive treatment in the period January 2013 - February 2019 at the National Center for Epilepsy at Oslo University Hospital, Norway.

RESULTS

Clinical data were available for 175 mainly adult patients with drug-resistant epilepsy with mean treatment duration of 16.1 months. We found that 23% (40 patients) were responders (i.e., achieving more than 50% reduction in seizure frequency), four of whom became seizure free, 29% (51 patients) experienced a modest effect, whereas for 29% (50 patients) perampanel had no seizure-reducing effect. A paradoxical effect, with seizure aggravation, was reported in 9% (15 patients). The responder rate was significantly higher in those with slow vs. fast dosage titration. Logistic regression analysis showed better efficacy among those with generalized vs. those with focal epilepsy. Adverse effects were reported by 135 patients (77%), ranging from mild (34%), to moderate (41%) and severe (2%). In 55 patients (41%), these adverse effects resulted in discontinuation of treatment with perampanel. The most frequent adverse effects were psychiatric symptoms (34%), dizziness (31%), and sleepiness (26%). Of the 31 patients for whom serum concentration measurements were available, the mean daily perampanel dose was 6.3 mg (SD 3.0), with a mean serum concentration at steady state of 1.03 μmol/L (range: 0.15-3.59 μmol/L). There were pronounced differences between patients, as demonstrated by a 12-fold variability in the range of concentration/dose (C/D)-ratios (0.06 to 0.69 μmol/L/mg), where enzyme inducers contributed.

CONCLUSION

Our results demonstrate that perampanel had a modest seizure-reducing effect in this very treatment-resistant patient group. Predictors of treatment success were generalized epilepsy and slow dosage titration. In patients without a history of psychiatric problems, clinicians could consider increasing dose of perampanel beyond 6 mg daily, taking co-medication and serum concentrations into account.

Differential acute impact of therapeutically effective and overdose concentrations of lithium on human neuronal single cell and network function

Lithium salts are used as mood-balancing medication prescribed to patients suffering from neuropsychiatric disorders, such as bipolar disorder and major depressive disorder. Lithium salts cross the blood-brain barrier and reach the brain parenchyma within few hours after oral application, however, how lithium influences directly human neuronal function is unknown. We applied patch-clamp and microelectrode array technology on human induced pluripotent stem cell (iPSC)-derived cortical neurons acutely exposed to therapeutic (<1 mM) and overdose concentrations (>1 mM) of lithium chloride (LiCl) to assess how therapeutically effective and overdose concentrations of LiCl directly influence human neuronal electrophysiological function at the synapse, single-cell, and neuronal network level. We describe that human iPSC-cortical neurons exposed to lithium showed an increased neuronal activity under all tested concentrations. Furthermore, we reveal a lithium-induced, concentration-dependent, transition of regular synchronous neuronal network activity using therapeutically effective concentration (<1 mM LiCl) to epileptiform-like neuronal discharges using overdose concentration (>1 mM LiCl). The overdose concentration lithium-induced epileptiform-like activity was similar to the epileptiform-like activity caused by the GABA_A-receptor antagonist. Patch-clamp recordings reveal that lithium reduces action potential threshold at all concentrations, however, only overdose concentration causes increased frequency of spontaneous AMPA-receptor mediated transmission. By applying the AMPA-receptor antagonist and anti-epileptic drug Perampanel, we demonstrate that Perampanel suppresses lithium-induced epileptiform-like activity in human cortical neurons. We provide insights in how therapeutically effective and overdose concentration of lithium directly influences human neuronal function at synapse, a single neuron, and neuronal network levels. Furthermore, we provide evidence that Perampanel suppresses pathological neuronal discharges caused by overdose concentrations of lithium in human neurons.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

New Methods Used in Pharmacokinetics and Therapeutic Monitoring of the First and Newer Generations of Antiepileptic Drugs (AEDs)

The review presents data from the last few years on bioanalytical methods used in therapeutic drug monitoring (TDM) of the 1st-3rd generation and the newest antiepileptic drug (AEDs) cenobamate in patients with various forms of seizures. Chemical classification, structure, mechanism of action, pharmacokinetic data and therapeutic ranges for total and free fractions and interactions were collected. The primary data on bioanalytical methods for AEDs determination included biological matrices, sample preparation, dried blood spot (DBS) analysis, column resolution, detection method, validation parameters, and clinical utility. In conclusion, the most frequently described method used in AED analysis is the LC-based technique (HPLC, UHPLC, USLC) combined with highly sensitive mass detection or fluorescence detection. However, less sensitive UV is also used. Capillary electrophoresis and gas chromatography have been rarely applied. Besides the precipitation of proteins or LLE, an automatic SPE is often a sample preparation method. Derivatization was also indicated to improve sensitivity and automate the analysis. The usefulness of the methods for TDM was also highlighted.

Relationship between plasma concentrations and clinical effects of perampanel: A prospective observational study

PURPOSE

The purpose of the study was to investigate the potential correlation between plasma concentration of the newer antiseizure medication (ASM) perampanel (PMP) and both tolerability and seizure control in patients with epilepsy.

METHODS

The study design was multicenter, open, and prospective. Plasma samples were collected in the morning 12 h apart from once-a-day bedtime PMP dose. Perampanel tolerability was assessed on the day of drug monitoring by clinical examination and patients' interview. Response to PMP was defined as ≥50% reduction from baseline seizure frequency (pretreatment). The main outcomes were the comparisons of PMP plasma concentration-to-weight-adjusted dose ratio (C/D) [(μg/mL)/(mg/kg/day)] between patients with and without PMP-related adverse effects (AEs) and between responders and nonresponders.

RESULTS

Ninety-seven patients (54% men), mean ± SD age 36 ± 14 years were enrolled in the study. The mean PMP dose was 6.7 ± 2.3 mg, drug treatment averaged 46 ± 34 weeks. The mean plasma concentration was 360 ± 268 ng/mL (range: 37-1213 ng/mL). Forty patients (41%) reported at least one AE, mainly dizziness and behavioral changes. No significant difference was found in median PMP C/Ds between patients with (2.94) and without (2.76) AEs, otherwise comparable for clinical variables. Forty-four patients (45%) were responders, at a median PMP C/D of 3.10, similar to the value of 2.76 found in nonresponders. These two groups also overlapped for clinical characteristics.

CONCLUSION

This is the first prospective real-life study to evaluate the relationship between PMP plasma concentrations, seizure control, and AEs. In line with the few real-world available data, we did not find any significant correlation between PMP plasma concentrations and both tolerability and seizure control.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Quantification of the Plasma Concentrations of Perampanel Using High-Performance Liquid Chromatography and Effects of the CYP3A4*1G Polymorphism in Japanese Patients

Here, we developed a novel high-performance liquid chromatography (HPLC) method for quantification of perampanel in clinical practice and investigated the relationships between the plasma concentrations of perampanel obtained by this HPLC method and the CYP3A4*1G polymorphism. The developed HPLC method was validated based on US Food and Drug Administration. The developed HPLC method could be performed with a plasma volume of only 200 μL and had a limit of quantification (LOQ) of 2.5 ng/mL. The coefficients of variation (CVs) for intra- and inter-day assays were less than 10.4 and 7.2%, respectively, and the accuracy was <2.4% for both assays. A total of 12 patients who received 2 mg perampanel had C0 values ranging from 70.5 to 451 ng/mL, and the CV showed a large variation of 51.4%. No correlations were observed between the dose-adjusted C0 and the CYP3A4*1G polymorphism. This method was superior to previously reported methods in terms of plasma volume and LOQ and was clinically applicable. Perampanel showed high variations in individual plasma concentrations; however, individual differences could not be predicted from analysis of the CYP3A4*1G polymorphism before perampanel administration. Therefore, after beginning perampanel treatment, the dose should be determined based on the observed plasma concentration.

The Effectiveness of Perampanel for Myoclonic Seizures in Down Syndrome with Isodicentric Chromosome 21

Epileptic seizures are common in the elderly Down syndrome population. We encountered a patient with Down syndrome in whom karyotyping showed the rare isodicentric chromosome 21 and who suffered from myoclonic seizures. A 52-year-old woman with Down syndrome experienced sudden onset of drowsiness and frequent myoclonic jerks in the upper body. Video-EEG recordings demonstrated generalized polyspike-wave discharges consistent with myoclonic jerks, which were exacerbated by photo-stimulation. Her myoclonus completely resolved with perampanel administration. Perampanel was effective for myoclonic seizures in our patient. We suggest that perampanel is an option as first-line therapy for epilepsy and myoclonus in elderly Down syndrome patients.

Effect of Geraniol and Citronellol Essential Oils on the Biophysical Gating Properties of AMPA Receptors

Essential oils have been advertised endlessly to be very beneficial for the health of humans, and an extensive amount of research examines the validity of such claims. In contribution, the current study evaluates the neuroprotective properties of Citronellol and Geraniol essential oils (EOs). In relationship to the biophysical gating properties of different the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) subunits, the EOs were administered to HEK293 (Human embryonic kidney 293) cells and examined for any inhibition and effect on desensitization or deactivation rates, using whole-cell patch-clamp electrophysiology. Our results demonstrated the highest levels of inhibition from Citronellol oil by four-fold on all AMPARs subunits. Likewise, Geraniol oil had a similar inhibiting impact on the receptors, and both oils decreased the desensitization and deactivation rates of the inhibited receptors. Thus, the examined EOs of this study portray neuroprotective qualities by targeting AMPARs activation and reducing desensitization and deactivation rates. Finally, the results of the current study entail a better understanding of AMPARs, provides a natural template for future drug synthesis to treat neurological diseases associated with excessive AMPAR activation, and offers a possible mechanism by which these essential oils deploy their ‘calming’ effect.