Study to Evaluate the Safety and Efficacy of USL261 (Intranasal Midazolam) in Patients With Seizure Clusters

Inclusion Criteria:

- Has a competent, adult caregiver who can recognize and observe the subject's seizure
cluster episodes

- Has an established diagnosis of partial or generalized epilepsy that includes the
following:

- A documented history of seizure clusters lasting a minimum of 10 minutes

- Seizure cluster pattern is observable, stereotyped, and recognizably different
from the subject's other non-cluster seizure activity (if any)

- A second seizure in the seizure cluster typically occurring within 6 hours from
the time of cluster recognition

- A seizure cluster pattern composed of multiple (≥ 2) partial or generalized
seizures

- A seizure cluster pattern established > 3 months before Visit 1

- A frequency of ≥ 3 seizure clusters during the year before Visit 1

- At least 1 seizure cluster occurring ≤ 4 months before Visit 1

- Seizure cluster pattern is confirmed by a central reviewer

- Currently on a stable regimen of AEDs (no changes in type of AEDs) since Visit 1 and
for ≥ 7 days before Visit 2, with or without intermittent use of benzodiazepines at a
constant dose

- Weight is 40kg to 125kg, inclusive

Exclusion Criteria:

- Has a neurological disorder that is likely to progress in the next year

- Has severe chronic cardio-respiratory disease

- Has had psychogenic, non-epileptic seizure(s) within the 5 years before Visit 1

- Has a history of their stereotypical seizure cluster progressing to status epilepticus
within the 2 years before Visit 1

- Has a history of acute narrow-angle glaucoma.

- Has had active suicidal plan/intent or active suicidal thoughts in the 6 months before
Visit 1 or a suicide attempt in the past 5 years

- Currently using a VNS unless the device has been implanted for at least 6 months and
the setting stable for 4 weeks before Visit 1