Rationale: Cenobamate (CNB) is an anti-seizure drug developed for the treatment of focal onset seizures. It was approved by the Food and Drug Administration (FDA) in November of 2019. Recent studies had shown significant improvement of refractory focal epilepsy, therefore, we aimed to assess the effectiveness and side effects of cenobamate in our clinical practice.
Methods: The data analyzed was obtained from the Hospital pharmacy that was used to prescribe cenobamate to first-time users, and from chart review from September 2022 to May 2023. The timeframe of these prescriptions was from 10/1/2020 to 9/30/2022. A total of 342 unique patients had been prescribed cenobamate. We evaluated a randomly screened sample of 53 patients using selection criteria of age ≥ 18 years old, cenobamate dose ≥150mg. We included patients who initiated treatment with cenobamate but did not continue the medication due to adverse effects. The primary endpoint was the proportion of patients who became seizure-free after adding cenobamate. Secondary endpoints were reduction of seizure frequency or severity and reduction in the number of antiseizure medications. We also assessed the most common side effects reported in the chart. Of the 53 randomly screened patients for chart review, 4/53 had insufficient follow up to evaluate the effects of cenobamate, and 1/53 elected not to start the drug. Therefore, results are based on the review of the remaining 48 charts.
Results:
From our sample of 48 patients, 13 were on monotherapy at last follow-up visit. 12/13 reported no seizures in the observation period. For 4/13, the observation period was over 12 months. For 3/13, the observation period was 6-12 months. For 1/13, the observation period was 3-6 months. For 4/13, the observation period was < 3 months. 1/13 patient was lost to follow up. From our sample of 26 patients on polytherapy, 20 reported no seizures in the observation period. For 7/26, the observation period was over 12 months. For 4/26, the observation period was 6-12 months. For 4/26, the observation period was 3-6 months. For 5/26, the observation period was < 3 Months.
Overall, 29/48 patients reported subjective improvement in seizure frequency or severity. 2/48 had no further convulsive seizures but continued to have auras. One patient reported transient improvement followed by seizure recurrence. 7/48 reported unclear or no improvement of seizures. Four patients were taken off CNB for unclear reasons. 1/48 stopped the treatment due to the cost of the drug.
Of the 26 patients receiving polytherapy including cenobamate, five patients had a reduction in the number of medications. 4/5 reduced by half, 1/5 reduced by two-thirds.
The adverse effects reported included fatigue n=15, gait imbalance n= 7, drowsiness n=5, falls n=1, mood disorders (n=3), tongue numbness n=1, dizziness n=1, slurred speech n=1, diplopia n=1, stuttering n=1 and urinary tract infection n=1.
Conclusions: In patients with focal epilepsy, we observed seizure freedom over a 12-month period in 30% of the patients on monotherapy and 26.9% of patients on polytherapy with cenobamate. Cenobamate improved seizure frequency and/or severity in 60.4% of our patient population.
Funding: None