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

An Open-Label Safety Study of USL261 in the Outpatient Treatment of Subjects With Seizure Clusters

The purpose of this study is to examine the long-term safety and tolerability of USL261 in the treatment of seizure clusters.

Participants who completed study P261-401 (NCT01390220), a randomized double-blind study of USL261 (intranasal midazolam) versus placebo to acutely treat a seizure cluster episode, were eligible to to enroll in this open-label extension study (P261-402). The participant's caregiver administered a USL261 5 milligram (mg) dose for a seizure episode meeting study criteria. A second USL261 5 mg dose could be administered after 10 minutes and up to 6 hours after the first dose for persistent or recurrent seizures, unless the participant met exclusions to administration of the second dose. A participant could have more than 1 seizure cluster episode treated during his/her study participation.

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