Therapeutic Drug Monitoring of Perampanel in Children With Refractory Epilepsy: Focus on Influencing Factors on the Free-Perampanel Concentration

Population Pharmacokinetics of Perampanel in Chinese Pediatric and Adult Patients With Epilepsy

BACKGROUND

Perampanel is a promising epilepsy treatment with an innovative mechanism of action. This study was performed to investigate the factors affecting perampanel clearance in a population pharmacokinetic (PPK) model of Chinese pediatric and adult patients with epilepsy.

METHODS

A total of 135 perampanel plasma concentrations from 125 patients with epilepsy were analyzed using the PPK model with nonlinear mixed-effects modeling. One-compartment and proportional residual models best described the pharmacokinetics of perampanel. Covariate effects on the model parameters were assessed using forward and backward elimination. Goodness-of-fit, bootstrapping, visual predictive checks, and normalized prediction distribution errors were used to evaluate the model. Monte Carlo simulations were conducted to assess the impact of covariate combinations on perampanel plasma concentrations at different dosages.

RESULTS

In the final PPK model, body weight (BW), concomitant carbamazepine (CBZ), oxcarbazepine (OXC), and C-reactive protein (CRP) levels significantly influenced perampanel clearance. The interindividual clearance was calculated as follows: 0.84 × (BW/70)0.53 × eCBZ × eOXC × eCRP (CBZ = 0.98, when comedicated with carbamazepine; OXC = 0.43, when comedicated with oxcarbazepine; CRP = -0.69, when CRP >15 mg/L, otherwise = 0). The estimates (relative standard error) for clearance and apparent volume of distribution of the final model were 0.84 L/h (8.75%) and 64.35 L (19.78%), respectively. The model maintained its stability and effectiveness with moderate predictability.

CONCLUSIONS

BW and CBZ, OXC, and CRP levels may influence perampanel clearance in both pediatric and adult patients with epilepsy according to a population pharmacokinetic model that included real-world data.

Effects of CYP3A5*3 genetic polymorphisms on the pharmacokinetics of perampanel in Chinese pediatric patients with epilepsy

PURPOSE

This study was the first to evaluate the effect of CYP3A5*3 gene polymorphisms on plasma concentration of perampanel (PER) in Chinese pediatric patients with epilepsy.

METHODS

We enrolled 98 patients for this investigation. 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 checkup.

RESULTS

The plasma concentration showed a linear correlation with the daily dose taken ( r  = 0.17; P  < 0.05). The ineffective group showed a significantly lower plasma concentration of PER (490.5 ± 297.1 vs. 633.8 ± 305.5 μg/ml; P  = 0.019). For the mean concentration-to-dose (C/D) ratio, the ineffective group showed a significantly lower C/D ratio of PER (3.2 ± 1.7 vs. 3.8 ± 2.0; P  = 0.040). The CYP3A5*3 CC genotype exhibited the highest average plasma concentration of PER at 562.8 ± 293.9 ng/ml, in contrast to the CT and TT genotypes at 421.1 ± 165.6 ng/ml and 260.0 ± 36.1 ng/ml. The mean plasma PER concentration was significantly higher in the adverse events group (540.8 ± 285.6 vs. 433.0 ± 227.2 ng/ml; P  = 0.042).

CONCLUSION

The CYP3A5*3 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 CYP3A5*3 genetic genotype should be factored in when prescribing PER to 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.