• Patients must be ≥2 and \<18 years of age.

• Patients must have a clinical diagnosis of DS confirmed by the Epilepsy Study Consortium, Inc. (ESCI) and as defined by:

• Onset, prior to 12 months of age, of recurrent focal with motor signs, hemiclonic, or generalized tonic-clonic seizures.No other known etiology causing clinical DS manifestations..

• Patient must have a documented pathogenic, likely pathogenic variant, or variant of uncertain significance in the sodium voltage-gated channel type 1 alpha subunit (SCN1A) gene. Patients who have SCN1A testing results of Negative (no variants identified) cannot be randomized.

• Patient must experience the required number of major motor seizures during the 6-week Observation Period. Major motor seizure types included are Seizure types included in counts are Hemiclonic, Focal with Motor Signs, Focal to Bilateral Tonic-Clonic, Generalized Tonic-Clonic, Tonic, Tonic/Atonic (Drop Attacks with fall or risk of fall), and Bilateral Clonic.

• Patient must have used at least 2 prior interventions for seizures. These can include anti-seizure medications (ASMs), ketogenic diet and/or vagus nerve stimulation (VNS) with either lack of adequate seizure control or discontinued due to an AE(s). These interventions can be ongoing therapies.

• Patient must be taking at least one ASM. Benzodiazepines or ASMs used on a standing basis (i.e., not as needed \[PRN\]) for any indication will be considered an ASM.

• Patients' maintenance ASMs and interventions for seizures (i.e., ketogenic diet or VNS), as well as any marijuana- or cannabinoid-based products, must have been stable (unless adjusted for weight) during the Baseline Period.