High-performance liquid chromatography-tandem mass spectrometry method for the determination of perampanel, a novel α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor antagonist in human plasma

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.

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.

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.

Evaluation of Perampanel in the Presence of its Degradation Products and Process-Related Impurities by Validated Stability-Indicating Reverse Phase High Performance Liquid Chromatography Method

A novel stability-indicating isocratic reverse phase high-performance liquid chromatographic method was developed for the quantitative determination of perampanel in the presence of degradation products and its process-related impurities. Good resolution was achieved between the peaks corresponding to process-related impurities and degradation products from the analyte using Shim-pack GIST C18 column with mobile phase, potassium dihydrogen phosphate (pH 2.5; 30 mM)-acetonitrile (45: 55, v/v) at a wavelength of 294 nm. Perampanel and its impurities were well-separated within a run time of 7 min. To show the stability-indicating power of the method, forced degradation studies were performed on bulk samples of perampanel as per ICH prescribed stress condition using acid, base, hydrolytic, oxidative and photolytic degradation conditions. The degradation products were resolved from main peak and its impurities. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. This method was also applied for assay and related substances determination of perampanel in bulk and pharmaceutical dosage form.

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.

Determination of Impurities in Perampanel Bulk Drugs by High- Performance Liquid Chromatography and Gas Chromatography

Background:

High-performance liquid chromatography (HPLC) method has been used to detect related impurities of perampanel. However, the detection of impurities is incomplete, and the limits of quantification and detection are high. A sensitive, reliable method is in badly to be developed and applied for impurity detection of perampanel bulk drug.

Objective:

Methodologies utilising HPLC and gas chromatography (GC) were established and validated for quantitative determination of perampanel and its related impurities (a total of 10 impurities including 2 genotoxic impurities).

Methods:

The separation was achieved on a Dikma Diamonsil C18 column (250 mm × 4.6 mm, 5 μm) with the mobile phase of 0.01 mol/L potassium dihydrogen phosphate solution (A) and acetonitrile (B) in gradient elution mode. The compound 2-bromopropane was determined on an Agilent DB-624 column (0.32 mm × 30 m, 1.8 μm) by electron capture detector (μ-ECD) with split injection ratio of 1:5 and proper gradient temperature program.

Result:

Both HPLC and GC methods were established and validated to be sensitive, accurate and robust according to the International Council for Harmonization (ICH) guidelines. The methods developed were linear in the selected concentration range (R2≥0.9944). The average recovery of all impurities was between 92.6% and 103.3%. The possible production mechanism of impurities during the synthesis and degradation processes of perampanel bulk drug was also discussed. Five impurities were analyzed by liquid chromatography–mass spectrometry (LC-MS). Moreover, two of them were simultaneously characterized by LC-MS, IR and NMR.

Conclusion:

The HPLC and GC methods were developed and optimized, which could be applied for quantitative detection of the impurities, and further stability study of perampanel.

Bioequivalence of perampanel fine granules and tablets in healthy Japanese subjects

Objective: Perampanel is an approved anti-seizure drug. A new formulation of perampanel fine granules (FG; 1% perampanel) has been developed for patients who are unable to take tablets. Bioequivalence between the 4-mg FG and tablet perampanel formulations, as well as their safety and tolerability, were assessed. Materials and methods: In this phase I, single-center, open-label, 2-period, 2-sequence, crossover, bioequivalence study (NCT03399734), healthy Japanese subjects were randomized to receive single doses of the 4-mg FG perampanel and 4-mg perampanel tablet (separated by a ≥ 6-week washout period). Plasma samples for perampanel concentration analysis were collected pre-dose and at intervals up to 168 hours post-dose. The maximum observed concentration (C_max) and area under the concentration–time curve from time zero to 168 hours (AUC_(0–168h)) were used to assess the bioequivalence of the two formulations. Results: The 90% confidence intervals (CIs) for the geometric mean ratio of test/reference for C_max and AUC_(0–168h) were within the bioequivalence criteria of 80 – 125% (C_max 90% CI 90.8%, 110%; AUC_(0–168h) 90% CI 98.2%, 112%; N = 21). 10/24 (41.7%) subjects with FG experienced ≥ 1 treatment-emergent adverse event (TEAE). The events were mild in severity and resolved within 4 hours of onset. There were no deaths, severe TEAEs, serious AEs, or TEAEs leading to study-drug withdrawal. Conclusion: Bioequivalence of 4-mg FG and 4-mg tablet of perampanel was demonstrated. Both perampanel formulations were generally safe and well tolerated. These data suggest that perampanel FG may be a suitable alternative formulation for patients with epilepsy who have difficulties taking perampanel tablets.

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.

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.

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.

Therapeutic Drug Monitoring for Perampanel in Japanese Epilepsy Patients: Influence of Concomitant Antiepileptic Drugs

BACKGROUND

Perampanel is a new antiepileptic drug (AED) that acts as a noncompetitive α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor antagonist and is mainly metabolized by cytochrome P450 (CYP) 3A4. This study evaluated the influence of concomitant AEDs on the serum concentration profile of perampanel.

METHODS

A total of 215 serum samples obtained from 76 patients aged 12 years or older were analyzed for routine therapeutic drug monitoring, and the concentration-to-dose ratio (CD ratio) of perampanel was compared among patients on various AED regimens.

RESULTS

In patients not taking concomitant enzyme-inducing AEDs, the mean CD ratio was 3963 ng·mL·mg·kg (range: 1793-13,299). By contrast, the mean CD ratio was lower in patients using enzyme-inducing AEDs [1760 (range: 892-3090), 2256 (range: 700-4703), and 1120 (range: 473-1853) ng·mL·mg·kg in patients taking phenytoin, phenobarbital, and carbamazepine, respectively], and carbamazepine had a significantly greater reduction in the CD ratio compared with phenytoin or phenobarbital (P < 0.001). Twenty-one patients responded with ≥50% reduction of seizure frequency from baseline, and their mean serum perampanel concentration was 450 ng/mL (range: 85-1500).

CONCLUSIONS

There is a large interindividual variation in CD ratio of perampanel because its metabolism is highly susceptible to interactions with enzyme-inducing AEDs. Therapeutic drug monitoring could be clinically useful for determining the influence of AED CYP3A4 inducers on perampanel concentrations.

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

OBJECTIVES

Explore perampanel pharmacokinetics (PK) in all subjects (aged ≥12 years) vs adolescents (aged ≥12 to ≤17 years) with partial-onset seizures (POS) and identify factors explaining between-subject variability in efficacy using a population PK/pharmacodynamic (PD) analysis.

MATERIALS & METHODS

Population PK analysis was performed using nonlinear mixed-effect modeling with data from phase II/III randomized, double-blind, placebo-controlled studies of adjunctive perampanel in POS. Perampanel exposure was predicted for all subjects and adolescents. Population PK/PD analyses were performed using data from phase III studies to explore the relationship between perampanel exposure and 28-day average seizure frequency and responder probability.

RESULTS

Pooled perampanel PK data from 1318 subjects were described by a one-compartment disposition model. In the absence of antiepileptic drugs (AEDs) affecting perampanel PK, estimated perampanel apparent clearance (CL/F) was 0.668 L/h (all subjects) and 0.682 L/h (adolescent subjects). Co-administration of carbamazepine and oxcarbazepine/phenytoin reduced perampanel exposure. Gender, Asian race (excluding Japanese or Chinese), and increasing alanine aminotransferase lowered perampanel CL/F, but differences were small and not considered clinically relevant. Adolescent outcomes were similar to the total population. Based on PK/PD data from 1748 subjects, percent reduction in 28-day average seizure frequency from baseline and responder probability increased with increasing perampanel exposure; concomitant CYP3A-inducing AEDs lowered perampanel exposure but did not impact the slope for responder probability.

CONCLUSIONS

These results are consistent with previous analyses but expand on these through inclusion of a larger number of patients from different ethnic groups, and demonstrate that outcomes were similar between adults and adolescents.

An Updated Overview on Therapeutic Drug Monitoring of Recent Antiepileptic Drugs

Given the distinctive characteristics of both epilepsy and antiepileptic drugs (AEDs), therapeutic drug monitoring (TDM) can make a significant contribution to the field of epilepsy. The measurement and interpretation of serum drug concentrations can be of benefit in the treatment of uncontrollable seizures and in cases of clinical toxicity; it can aid in the individualization of therapy and in adjusting for variable or nonlinear pharmacokinetics; and can be useful in special populations such as pregnancy. This review examines the potential for TDM of newer AEDs such as eslicarbazepine acetate, felbamate, gabapentin, lacosamide, lamotrigine, levetiracetam, perampanel, pregabalin, rufinamide, retigabine, stiripentol, tiagabine, topiramate, vigabatrin, and zonisamide. We describe the relationships between serum drug concentration, clinical effect, and adverse drug reactions for each AED as well as the different analytical methods used for serum drug quantification. We discuss retrospective studies and prospective data on the serum drug concentration-efficacy of these drugs and present the pharmacokinetic parameters, oral bioavailability, reference concentration range, and active metabolites of newer AEDs. Limited data are available for recent AEDs, and we discuss the connection between drug concentrations in terms of clinical efficacy and nonresponse. Although we do not propose routine TDM, serum drug measurement can play a beneficial role in patient management and treatment individualization. Standardized studies designed to assess, in particular, concentration-efficacy-toxicity relationships for recent AEDs are urgently required.

Simple and rapid validated HPLC-fluorescence determination of perampanel in the plasma of patients with epilepsy

We present a simple and fast high-performance liquid chromatography method with fluorescence detection for the determination of the antiepileptic drug perampanel in human plasma. The chromatographic separation was performed on a Kinetex PFP (100 × 2.6 mm, 4.6 µm) column, using a mobile phase of sodium acetate 0.03 M pH 3.7 and acetonitrile (40/60, v/v), at a flow rate of 0.8 mL/min. Total chromatography time for each run was 5 min. Sample preparation (250 µL) involved only one simple precipitation step by acetonitrile spiked with mirtazapine as internal standard. The method was validated over a concentration range of 20-1000 ng/mL and successfully applied to measure perampanel concentrations in plasma samples obtained from patients with epilepsy. This assay combines the high specificity of fluorescence detection with a very simple and fast sample pretreatment and can offer real advantages over existing methods in terms of simplicity and transferability to a therapeutic drug monitoring setting.

Pharmacokinetics and brain uptake study of novel AMPA receptor antagonist perampanel in SD rats using a validated UHPLC-QTOF-MS method

Perampanel (PER) is a novel AMPA receptor antagonist for antiepileptic therapy and is prospective for the treatment of other neurological disorders. A highly sensitive and rapid UHPLC-QTOF-MS method was developed for the quantification of PER in plasma/brain homogenate of SD rat with alogliptin as an internal standard (IS). Chromatographic separation was carried out on an Acquity UPLC HSS Cyano column (100mm×2.1mm, 1.8μm) using gradient mobile phase consisting of 0.1% formic acid and acetonitrile at a flow rate of 0. 4mL/min. Sample preparation was carried out by a simple protein precipitation method. The mass spectrometric analysis of target ions at [M+H]⁺m/z 350.1288 for PER and m/z 340.1779 for IS was monitored with extracted ion chromatography. The developed analytical method meets the US-FDA and EMA bioanalytical guidelines and was found to be precise, accurate, selective and rugged. It exhibited good sensitivity (0.4ng/mL) and linearity over a range of 0.4-400ng/mL in both the bio-matrices. The method was successfully applied to pharmacokinetics and brain uptake study of PER after oral administration to SD rats. The study results showed PER has penetrated the blood-brain barrier, brain to plasma ratio (Kp) was found to be 0.62±0.05 and its rapidly eliminated from the brain.