Changes in perampanel levels during de‐induction: Simulations following carbamazepine discontinuation

OBJECTIVE: To evaluate the time course of changes in perampanel levels when co-administered with carbamazepine, and following carbamazepine discontinuation, using a physiologically based pharmacokinetic (PBPK) model. METHODS: The PBPK model was developed, verified using clinical PK data, and used to simulate the effect of abrupt discontinuation and down-titration (75 mg twice daily [bid]/wk) of co-administered carbamazepine 300 mg bid on the PK of perampanel once daily (qd). Perampanel dose tapering (8-4 mg) and up-titration (2-6 mg) were simulated during abrupt carbamazepine 300 mg bid discontinuation to identify a titration schedule that minimizes changes in perampanel plasma concentrations. RESULTS: The PBPK model accurately reproduced perampanel plasma concentration-time profiles from clinical studies in single- and multiple-dose regimen simulations, including multiple-dose carbamazepine co-administration. The time course of return to pre-induced perampanel levels occurred more slowly following carbamazepine down-titration (~48 days after first down-titration) vs abrupt discontinuation (~25 days). Perampanel dose tapering (8-4 mg) at abrupt carbamazepine discontinuation produced minimal changes in steady-state concentrations, which returned to the levels observed during carbamazepine co-administration in ~15 days from the time of carbamazepine discontinuation. When perampanel was up-titrated in the presence of carbamazepine, return to steady state occurred more slowly when carbamazepine was down-titrated weekly (~45 days) vs abrupt discontinuation (~24 days). CONCLUSION: This PBPK model simulated and predicted optimal perampanel dose tapering and up-titration schedules for maintaining perampanel levels during conversion to monotherapy. These results may guide physicians when managing conversion from perampanel polytherapy with concomitant enzyme-inducing anti-seizure medications to monotherapy.