The cenobamate-clobazam interaction- evidence of synergy in addition to pharmacokinetic interaction.

OBJECTIVES

Report insights into the pharmacokinetic and pharmacodynamic interaction between cenobamate (CNB) and clobazam (CLB), derived from data in patients enrolled at our center in a global multicenter open-label safety study of CNB.

MATERIALS &

METHODS

Patients in this study either took CLB at baseline (n = 6) or had CLB added after CNB titration to maximal dose (n = 5) in addition to other antiseizure medications. Clobazam was always administered as a single bedtime dose. Random serum concentrations of CLB and N-desmethylclobazam (N-CLB) were obtained.

RESULTS

Baseline daily CLB doses were 20-50 mg. Sedation began in the six baseline CLB patients at CNB doses of 25-100 mg. The N-CLB/ CLB ratio increased proportionally to the CNB dose. CLB was stopped in all six patients, five of whom were ≥50% responders. Seizure control deteriorated after stopping CLB, with only one remaining responder. Clobazam was restarted at 5 mg/d in five of the six patients. At the last follow-up, four of these patients were continuing CLB; two were seizure-free and 2 were ≥50% responders. Among the five patients that added 5 mg/d CLB de novo, three were responders. All patients were still on CNB at the end of the study.

DISCUSSION: Data suggest starting CLB dose reduction at CNB doses of 25-100 mg/d. Due to possible synergy, the addition of low-dose CLB could be considered in patients with incomplete response to CNB.