Mechanism of action and pharmacokinetics of pyrenoprene

INTRODUCTION

Epilepsy is a serious neurological condition that affects more than 50 million individuals globall.The Food and Drug Administration approved perampanel (Fycompa, Eisai, Inc.) in October 2012 as an adjunctive agent for the treatment of POS with or without secondary generalization in patients with epilepsy at least 12 years of age. In June 2015, the agency approved a second indication for primary generalized tonic-clonic (PGTC) seizures in patients with epilepsy who are at least 12 years of age.

MECHANISM OF ACTION

Perampanel (2-[2-oxo-1-phenyl-5-pyridin-2-yl-1,2 dihydropyridin-3-yl] benzonitrile hydrate) is a novel non-competitive selective antagonist at the postsynaptic ionotropic alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptor.1,8,9 In the nervous system, glutamate is known to be a major excitatory neurotransmitter, but the exact antiepileptic mechanism of perampanel in humans is unknown.8 Studies suggest that AMPA receptor antagonism can lead to reduced overstimulation and anticonvulsant effects, as well as inhibiting seizure generation and spread. In addition, AMPA receptor antagonists may prevent neuronal death.

PHARMACOKINETICS

Absorption

Administration of perampanel results in rapid and complete absorption with negligible first-pass metabolism. The median time to reach peak concentration varies between 0.5 to 2.5 hours fasting (delayed by two to three hours when taken with food). Peak plasma concentration is reached in approximately one hour (decreased by 40% when taken with food). It is worth noting that the extent of absorption is not affected by food.

Distribution

Fycompa is approximately 95% to 96% protein-bound in the concentration range of 20 ng/mL to 2,000 ng/mL.

CLINICAL TRIALS

Clinical trials of perampanel have been conducted with patients diagnosed with PGTC seizures, and with those undergoing uncontrolled, drug-resistant, or refractory POS. In all studies, the primary efficacy endpoint was the percent change in seizure frequency per 28 days, and a common secondary efficacy endpoint was the 50% responder rate. In the 2015 clinical trial conducted by French et al., patients with PGTC seizures who were taking 8 mg or the highest tolerated dose of perampanel showed a statistically significant reduction in the frequency of seizures compared with placebo.