Real-world clinical experience with intravenous perampanel in Japanese patients at perceived high risk for early postoperative or acute symptomatic seizures: A single-center retrospective observational study.

BACKGROUND

Intravenous perampanel (PER-IV), recently approved in Japan in April 2024, enables seizure management in patients who are unable to take oral medications. However, real-world data on its clinical use, safety, and transition outcomes remain limited, particularly in perioperative or acute care settings where temporary inability to take oral medication may occur.

METHODS

This retrospective single-center observational study analyzed all consecutive patients who received PER-IV between May 2024 and May 2025 as part of routine clinical care based on the treating physician's judgment. The primary outcome was the proportion of patients in the perioperative/acute group without clinically observable early postoperative or acute symptomatic seizures within 7 days after PER‑IV initiation. Secondary outcomes included the absence of clinically observable seizures in patients, and descriptive seizure-related outcomes after transition to oral PER at 14 and 90 days. Adverse events and the transition rate to oral therapy were also evaluated.

RESULTS

Eighty-six patients received PER-IV: 11 for focal seizures; 10 for generalized seizures; and 65 in the perioperative or acute phase due to a perceived high risk of early postoperative or acute symptomatic seizures. The most common PER-IV dose was 2 mg /day (82.5%), with a median infusion duration of 2.5 days. A clinically low observed incidence of seizures noted in patients who received PER-IV during the perioperative or acute phase with high seizure risk within 7 days after administration. In patients with focal and generalized seizures, the absence clinically observable seizures were observed in 81.8% and 70.0%, respectively, during the 7-day period. After transition to oral PER, the absence of clinically observable seizures remained descriptively stable at 14 days and up to 90 days. Adverse events occurred in 9 patients, with irritability being the most common (n = 5).

CONCLUSION

This retrospective observational study suggests feasibility and acceptable tolerability of PER-IV; however, preventive effects cannot be determined in this uncontrolled study without systematic EEG monitoring. PER-IV is a feasible and well-tolerated option in patients at increased risk of early postoperative or acute symptomatic seizures who are temporarily unable to take oral antiseizure medications, particularly during the perioperative or acute care period. Given the descriptive nature of this study, the absence of a control group, and potential selection bias, these findings should be interpreted cautiously.