Perampanel Pharmacokinetics in Children: Correlation of Dose With Serum Concentrations

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.

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.

Effectiveness and tolerability of adjunctive perampanel in pediatric patients (aged 4-12 years) with refractory epilepsy: An observational study

Information on the effects of perampanel in Chinese children ≤12 years of age with refractory epilepsy is limited; thus, we conducted an observational study to assess the effectiveness, safety, and tolerability of adjunctive perampanel in this pediatric population. In this study, we reviewed the medical records of pediatric patients aged 4 to 12 years with refractory epilepsy who were admitted to Children's Hospital of Soochow University and prescribed perampanel between January 2020 and January 2021. Effectiveness of perampanel was measured by 50% responder rates, seizure-freedom rates, and retention rates for up to 48 weeks. Adverse events were monitored and recorded throughout the study. A total of 34 patients (male, n = 15) who exhibited refractory epilepsy were included in this study, and 64.71% of patients had focal-onset seizures combined with generalized epilepsy. The mean (± standard deviation) age of patients was 7.21 (± 2.12) years, with a mean (± standard deviation) age at seizure onset of 4.57 (± 2.59) years. After the addition of perampanel, the 50% responder rates at 4, 8, 12, 24, 36, and 48 weeks were 37.50% (12/32), 43.75% (14/32), 53.13% (17/32), 59.38% (19/32), 59.38% (19/32), and 62.07% (18/29). Two patients withdrew from perampanel treatment due to adverse events in the first 2 weeks. Adverse events were reported by 44.12% (15/34) of patients, and the retention rates at 36 and 48 weeks were 94.12% (32/34) and 85.29% (29/34), respectively. Overall, perampanel exhibited good effectiveness, safety, and tolerability in the treatment of pediatric patients (aged 4-12 years) with refractory epilepsy. These findings suggest that personalized treatment and better baseline seizure control may increase the responder rate and retention rate of perampanel.

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.

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.