Study to Evaluate the Long-term Safety and Tolerability of USL261 in Patients With Seizure Clusters

Inclusion Criteria:

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

- Has successfully completed study P261-401, and the subject and caregiver have
demonstrated adequate compliance with P261-401 study procedures as determined by the
investigator

Exclusion Criteria:

- Has experienced status epilepticus during or since the P261-401 study

- In the opinion of the investigator, is experiencing an ongoing, uncontrolled,
clinically significant adverse event(s) from P261-401 at Visit 1 or did experience a
clinically significant adverse event in study P261-401 that might prevent the subject
from safely participating in the study

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

- Has a history of acute narrow-angle glaucoma

- Has a medical condition including uncontrolled cardiac, pulmonary, renal, hepatic, or
gastrointestinal disease that could interfere with the study, subject safety/safety
monitoring, or is not stable despite current therapy

- Subject has severe chronic cardio-respiratory disease or the need for ambulatory
oxygen

- Has had psychogenic, non-epileptic seizure(s) during or since the P261-401 study

- Has active suicidal plan or intent as determined by the C-SSRS at Visit 1 or medical
history

- Subject has had vagus nerve stimulator (VNS) implanted since the completion of study
P261-401