Open Label Extension to Assess the Long-Term Safety and Tolerability of ZYN002 in Children and Adolescents With FXS

This is an open-label extension, multiple-center study, to assess the long-term safety and tolerability of cannabidiol administered as ZYN002, a transdermal gel, for the treatment of child and adolescent patients with Fragile X Syndrome (FXS). Male and female patients with FXS will be treated for up to 72 months. Up to 450 male and female patients, ages 3 to 18 years will be enrolled. Parents/caregivers will apply the study gel twice daily for the 52-week treatment period. Participants from study ZYN-CL-016 who weigh less than or equal to 35 kg, will receive 1 sachet of ZYN002, applied every 12 hours (± 2 hours). Participants from study ZYN-CL-016 who weigh more than 35 kg will receive 2 sachets of ZYN002, applied every 12 hours (± 2 hours). Participants from study ZYN-CL-033 who weigh less than or equal to 30 kg, will receive 1 sachet of ZYN002, applied every 12 hours (± 2 hours). Participants from study ZYN-CL-033 who weigh more than 30 kg will receive 2 sachets of ZYN002, applied every 12 hours (± 2 hours). Participants from study ZYN-CL-033 who weigh more than 50 kg will receive 3 sachets of ZYN002, applied every 12 hours (± 2 hours). At the Investigator's discretion, the dose may be increased or decreased at any time after the first month of treatment (for example due to weight changes during the course of the study). Participants who are taking anti-epileptic drugs may have an additional one or two weeks of treatment after the 52 week treatment period to taper off study treatment. Blood samples will be collected for safety analysis of ZYN002. Additionally, the parents/caregivers will be asked to complete some questionnaires. There will be other questionnaires and scales that will be completed at the site by the study doctor and/or with the participant and their parents/caregivers. Patients that complete Month 12 will be allowed to continue for another 12 months of treatment if they qualify. Patients will be evaluated again annually at Months 24 and 36, and 48 in order to remain in the study.