Effectiveness of low-dose perampanel in focal epilepsy patients aged twelve or older in Southern China: an observational study

This real-world study from southern China retrospectively evaluated the effectiveness, tolerability, and retention of low-dose perampanel (PER 2–6 mg) in focal epilepsy and explored associated clinical factors. Based on the steady-state maintenance dose of PER (2, 4, or 6 mg/day), 190 patients were enrolled from July 2020 to August 2023. Outcomes included seizure reduction, responder rates (≥ 50% reduction), adverse events (AEs), and retention at 3, 6, 9, and 12 months. At 12 months, seizure frequency reductions were 100% (2 mg), 91% (4 mg), and 82.5% (6 mg). Efficacy rates at 12 months were 44.6% (2 mg), 50% (4 mg), and 66.8% (6 mg) (P = 0.168). Exploratory analyses suggested a higher responder rate with 6 mg versus 2 mg in patients with disease duration ≥ 5 years or focal seizures only (P = 0.023; P = 0.044). Multivariable analysis indicated that a lower number of concomitant ASMs was independently associated with better early response (6-month), while a shorter disease duration (< 5 years) was associated with better long-term (12-month) response, independent of the specific dose within the 2–6 mg range. AE incidence was lowest with 2 mg (14.3%) versus 4 mg (24.1%) and 6 mg (23.9%). Respective 12-month retention rates were 32.2, 46.8, and 58.6%. In conclusion, this study suggests that low-dose PER (2–6 mg) can achieve favorable short- and long-term seizure control in focal epilepsy patients aged ≥ 12 years, with a good tolerability profile. The benefits were particularly pronounced in those with a shorter disease duration (< 5 years) and those receiving monotherapy or early add-on therapy.