An Open-Label Extension Trial to Assess the Long-Term Safety of ZX008 (Fenfluramine Hydrochloride HCl) Oral Solution in Children and Young Adults With Dravet Syndrome

This is an international, multicenter, open-label, long-term safety study of ZX008 in
pediatric and young adult subjects with Dravet syndrome who participated in one of the core
studies (ZX008-1501 and ZX008-1502) and are candidates for continuous treatment for an
extended period of time. This trial will consist of a 36-month Open-Label Extension (OLE)
Treatment Period and a 2-week Post-Dosing Period.

Key Inclusion Criteria:

- Male or non-pregnant, non-lactating female, age 2 to 18 years, inclusive as of the day
of the core study Screening Visit.

- Satisfactory completion of the core study in the opinion of the investigator and the
sponsor.

- Subjects who are >18 to ≤35 years of age at the time of screening and did not
participate in one of the core studies may be eligible for participation.

- A documented medical history to support a clinical diagnosis of Dravet syndrome, where
convulsive seizures are not completely controlled by current antiepileptic drugs.

- Parent/caregiver is willing and able to be compliant with diary completion, visit
schedule and study drug accountability.

- Subject's parent/caregiver has been compliant with diary completion during the core
study, in the opinion of the investigator (eg, at least 90% compliant).

Key Exclusion Criteria:

- Current or past history of cardiovascular or cerebrovascular disease, myocardial
infarction or stroke.

- Current cardiac valvulopathy or pulmonary hypertension that is clinically significant
and warrants discontinuation of study medication.

- Current or past history of glaucoma.

- Moderate or severe hepatic impairment.

- Receiving concomitant therapy with: centrally-acting anorectic agents;
monoamineoxidase inhibitors; any centrally-acting compound with clinically appreciable
amount of serotonin agonist or antagonist properties, including serotonin reuptake
inhibition; atomoxetine, or other centrally-acting noradrenergic agonist;
cyproheptadine, and/or cytochrome P450 (CYP) 2D6/3A4/2B6 inhibitors/substrates.

- Currently taking carbamazepine, oxcarbamazepine, eslicarbazepine, phenobarbital, or
phenytoin, or has taken any of these within the past 30 days, as maintenance therapy.

- A clinically significant condition, or has had clinically relevant symptoms or a
clinically significant illness at Visit 1, other than epilepsy, that would negatively
impact study participation, collection of study data, or pose a risk to the subject.