This amendment addressed the following issues: * Clarified the definition of drop seizures. * Updated secondary objectives to include “Change in duration of subtypes of seizures”. * Updated eligibility criteria for the electroencephalogram. * Clarified criteria for withdrawal. * Updated contact details in line with a change in GW Research Ltd’s business address. * Changed the visit windows. * Included a review of seizure history by the Epilepsy Study Consortium. * Specified that participants would be stratified by age across treatment arms. * Amended wording to allow participants who suspended IMP due to an adverse event to resume dosing prior to complete recovery, provided that the adverse event was well tolerated. * Added recording of additional medical history including antiepileptic drugs (AEDs) and epilepsy-specific genetic testing. * Included additional questionnaires: Subject/Caregiver Global Impression of Change in Seizure Duration (S/CGICSD) and Pediatric Cannabinoid Withdrawal Scale. * Revised ITT analysis set criteria per Food and Drug Administration (FDA) request. * Modified statistical analysis testing of the primary endpoint and additional statistical analysis of the secondary endpoints. * Amended the exclusion criteria to include contraception requirements and previous cannabis use. * Changed the statistical methods dealing with missing data. * Clarified that IMP usage was to be recorded via the paper diary to reduce the IVRS call time. * Incorporated additional assessments: pharmacokinetic, Cognitive Assessment Battery (CAB), Growth and Development measurements, insulin-like growth factor-1 levels, menstruation, and Tanner Staging per FDA request. * Updated references to reflect the latest safety information. * Corrected minor spelling/formatting/consistency issues.

This amendment incorporated recommendations received from the United States competent authority (FDA). * Added measurement of serum triglycerides. * Clarified that the EOT visit would also be labeled as the Withdrawal visit. * Added 12-lead electrocardiogram and clinical laboratory assessments at the ‘End of Taper’ visit for participants who withdrew early and tapered IMP and for participants who opted not to enter the OLE study. * Clarified that during the follow-up of participants with potential cases of drug-induced liver injury, the levels of alanine or aspartate aminotransferase, total bilirubin, and alkaline phosphatase should be monitored until levels normalized or returned to normal. * Updated statistical analysis of the primary and secondary endpoints to include the full treatment period. * Updated lower age limit for Tanner Staging to include participants aged 10–17 (inclusive) or earlier if clinically indicated. * Specified that participants would be stratified by 4 age groups (2–5, 6–11, 12–17, and 18–55 years). In addition, the following changes were addressed: * Replaced wording of concomitant AED blood sampling in the event of an adverse event. * Clarification that the growth and development endpoint will only be assessed in participants < 18 years old. * Reclassified effects on menstruation as a safety measure. * Increased the number of participants per treatment group from 40 to 50 and amended the assumption that participants in the placebo group would experience a mean reduction in drop seizure frequency of 10% to 18%. * Replaced “High Dose Level” and “Low Dose Level” with “20 mg/kg/day” and “10 mg/kg/day,” respectively. * Clarified eligibility criteria. * Clarified blood sampling was only to be taken from participants weighing ≥ 20 kg. * Clarified statistical methods and liver function testing. * Removed the Socioeconomic Scale item from the CAB. * Amended responder and sensitivity analysis and the CGIC/CGICSD questionnaires.