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

Therapeutic drug monitoring of free perampanel concentrations in practice: A practical analytical technique based on centrifugal ultrafiltration sample separation

Objectives

The centrifugal ultrafiltration-high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was established to determine the free perampanel (PER) concentration in children with epilepsy.

Methods

Free PER concentration was obtained using centrifugal ultrafiltration devices. The internal standard was PER-D5. The method was investigated for selectivity, carryover, lower limit of quantification, calibration curve, accuracy, precision, matrix effects, recovery, and stability. The Spearman's correlation coefficient was used to evaluate the correlation between the free and total PER concentrations. A nonparametric test was used to estimate the effects of PER along with other antiepileptic drugs on the total and free PER concentrations.

Results

The free PER concentration was positively correlated with the total PER concentration in the 57 plasma samples (r = 0.793 > 0, P < 0.001). Additionally, the free PER concentrations were significantly (P < 0.05) increased in valproic acid (VPA) co-therapy (9.87 ± 5.83) compared with non-VPA co-therapy (5.03 ± 4.57).

Conclusions

The proposed method is efficient, sensitive, and suitable for detecting free PER concentrations in children with epilepsy. Simultaneously, the free PER concentration response to clinical outcomes in children with epilepsy was more clinically significant, particularly when combined with VPA.

Effects of CYP3A4 genetic polymorphisms on the pharmacokinetics and efficacy of perampanel in Chinese pediatric patients with epilepsy

OBJECTIVE

This study was the first to evaluate the effect of CYP3A4 gene polymorphisms on the plasma concentration and effectiveness of perampanel (PER) in Chinese pediatric patients with epilepsy.

METHODS

We enrolled 102 patients for this investigation. The steady-state concentration was determined after patients maintained a consistent PER dosing regimen for at least 21 days. Plasma PER concentrations were measured using liquid chromatography-tandem mass spectrometry. Leftover samples from standard therapeutic drug monitoring were allocated for genotyping analysis. The primary measure of efficacy was the rate of seizure reduction with PER treatment at the final check-up.

RESULTS

The CYP3A4×10 GC phenotype exhibited the highest average plasma concentration of PER at 491.1 ± 328.1 ng/mL, in contrast to the CC phenotype at 334.0 ± 161.1 ng/mL. The incidence of adverse events was most prominent in the CYP3A4×1 G TT and CYP3A4×10 GC groups, with rates of 77.8 % (7 of 9 patients) and 50.0 % (46 of 92 patients), respectively. Moreover, the percentage of patients for whom PER was deemed ineffective was least in the CYP3A4×1 G TT and CYP3A4×10 CC groups, recorded at 11.1 % (1 of 9 patients) and 10.0 % (1 of 10 patients), respectively. There was a significant correlation between PER plasma concentration and either exposure or toxicity (both with p < 0.05). We suggest a plasma concentration range of 625-900 ng/mL as a suitable reference for PER in Chinese patients with epilepsy.

CONCLUSION

The CYP3A4×10 gene's genetic polymorphisms influence plasma concentrations of PER in Chinese pediatric patients with epilepsy. Given that both efficacy and potential toxicity are closely tied to plasma PER levels, the CYP3A4 genetic phenotype should be factored in when prescribing PER to patients with epilepsy.

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.

Effect of Age, Comedications, and CYP3A4/5 Polymorphisms on Perampanel Exposure in Chinese Pediatric Patients With Epilepsy

Perampanel (PER) is a new type of antiseizure medication used for partial or generalized seizures. However, the plasma concentration shows obvious individual variability in children. The present study aims to ascertain the effect of age, comedications, and cytochrome P450 (CYP) 3A4/5 polymorphisms on PER exposure in Chinese pediatric patients with epilepsy. Clinical data were retrospectively collected in a tertiary children's hospital medical records system from January 2021 to December 2022. The influence factors on the daily dose, plasma concentration, and concentration-to-dose ratio (CDR) of PER were investigated. A total of 135 pediatric patients with 178 blood samples were involved. With a median daily dose of 4.0 mg (interquartile range, 3.0-5.0 mg), the median plasma concentration was 409.4 ng/mL (interquartile range, 251.7-639.4 ng/mL). The CDR in patients aged less than 4 years was significantly decreased by 48.0% and 39.1% compared with those aged 4-11 years and 12 years or older, respectively. Enzyme inducers significantly decreased the CDR of PER by 34.5%, while valproic acid showed an increase of 71.7%. In addition, genotype CYP3A5*3/*3 carriers presented a significant increase of 21.5% compared to the CYP3A5*1/*3 expresser. No correlations were observed between the CDR and CYP3A4∗1G polymorphism. PER showed high variations in individual plasma concentrations. Age younger than 4 years, comedication with enzyme inducers or valproic acid, and possession of the CYP3A5*3 genotype potentially predicted PER exposure in pediatric patients with epilepsy.

Plasma Concentration, Efficacy, and Tolerability of Perampanel in Chinese Pediatric Patients with Epilepsy: Real-World Clinical Experience

BACKGROUND

Information on the efficacy and plasma concentration of perampanel (PER) in Chinese pediatric patients with epilepsy is limited. Therefore, this real-world retrospective study aimed to assess the efficacy, tolerability, and plasma concentration of the maximum dose of PER for epilepsy treatment in Chinese pediatric patients.

METHODS

A total of 107 pediatric patients from 2 hospitals in China were enrolled in this study. The plasma concentration of PER was determined using ultrahigh-performance liquid chromatography. The primary efficacy endpoint was the seizure reduction rate after PER treatment at the last follow-up.

RESULTS

The response rate to PER therapy was 59.8% (64/107). The authors observed that patients younger than 6 years of age (n = 49) showed a significantly lower concentration-to-dose ratio than patients with ages between 6 and 14 years (n = 58) (2.2 ± 1.7 vs. 3.0 ± 1.8 mcg·mL -1 ·kg·mg -1 , respectively; P < 0.05). Patients who received enzyme-inducing antiseizure medication had significantly lower concentration-to-dose ratios than those who did not receive enzyme-inducing antiseizure medication (EIASM) (2.1 ± 1.8 vs. 3.1 ± 2.0 mcg·mL -1 ·kg·mg -1 , P < 0.05). A total of 37 patients (34.6%) reported treatment adverse events. Patients with somnolence and irritability had a significantly higher PER plasma concentration than the "no treatment-emergent adverse effect" groups ( P < 0.05).

CONCLUSIONS

PER is an effective and well-tolerated treatment option for patients with epilepsy. To ensure the clinical efficacy and safety of PER in pediatric patients, it is necessary to monitor its plasma concentrations.

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.

Effect of Serum Perampanel Concentration on Sporadic Amyotrophic Lateral Sclerosis Progression

BACKGROUND AND PURPOSE

To clarify the effect of perampanel (PER) on sporadic amyotrophic lateral sclerosis (sALS) progression, the relationship between the changes in Revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R) scores and serum PER concentrations was investigated.

METHODS

12 patients with sALS from our hospital who agreed to participate and completed the PER for sALS randomized phase 2 study were included. After completing the study, we retrospectively obtained serum PER concentration data from the patients. Based on their mean PER concentrations, we divided the patients who had been taking PER into two groups: four patients with a mean PER concentration of ≥400 ng/mL were assigned to the H group, and three with a mean PER concentration of <400 ng/mL were assigned to the L group. The control group consisted of five patients who had been taking a placebo. We obtained the ALSFRS-R scores of each patient at 36 and 48 weeks after randomization. The differences in ALSFRS-R scores at baseline (0 weeks) and each subsequent week were used in the analysis.

RESULTS

At 48 weeks, there were no differences in the degree of deterioration of the bulbar, upper and lower limb, and respiratory ALSFRS-R subscores and total ALSFRS-R score. However, at 36 weeks, the bulbar subscore was significantly lower in the H group than in the control group (p=0.032).

CONCLUSIONS

Because high PER concentrations may exacerbate bulbar symptoms in patients with sALS, serum PER measurements may be beneficial when patients with sALS are taking PER.

Polymorphisms Affecting the Response to Novel Antiepileptic Drugs

Epilepsy is one of the most frequent chronic neurologic disorders that affects nearly 1% of the population worldwide, especially in developing countries. Currently, several antiepileptic drugs (AEDs) are available for its therapy, and although the prognosis is good for most patients, 20%-30% amongst them do not reach seizure freedom. Numerous factors may explain AED-resistance such as sex, age, ethnicity, type of seizure, early epilepsy onset, suboptimal dosing, poor drug compliance, alcohol abuse, and in particular, genetic factors. Specifically, the interindividual differences in drug response can be caused by single nucleotide polymorphisms (SNPs) in genes encoding for drug efflux transporters, for the brain targets of AEDs, and for enzymes involved in drug metabolism. In this review, we used the PubMed database to retrieve studies that assessed the influence of SNPs on the pharmacokinetic (PK), pharmacodynamic (PD), and efficacy of new antiepileptic drugs. Our results showed that polymorphisms in the ABCB1, ABCC2, UGT1A4, UGT2B7, UGT2B15, CYP2C9, and CYP2C19 genes have an influence on the PK and efficacy of AEDs, suggesting that a genetic pre-evaluation of epileptic patients could help clinicians in prescribing a personalized treatment to improve the efficacy and the safety of the therapy.