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