A Long-Term Safety and Effectiveness Study to Evaluate Pitolisant in Adult Patients With Idiopathic Hypersomnia

This is a Phase 3 open-label study to evaluate the long-term safety and effectiveness of pitolisant in adult patients with IH. Patients who complete the Double-Blind Randomized Withdrawal Phase of study HBS-101-CL-010 (i.e., completed the End-of-Treatment \[EOT\] Visit/Visit 5 in the HBS-101-CL-010 study) and who continue to meet eligibility criteria for study HBS-101-CL-011 are eligible for enrollment. Enrolled patients will be dispensed open-label pitolisant and may be titrated up to a maximum dose of 35.6 mg, based on the Investigator's assessment of safety/tolerability and effectiveness, during a 3-week Titration Period (Day 1 to Day 21) in accordance with the schedule: * Week 1 (Day 1-7), 8.9 mg * Week 2 (Day 8-14), 17.8 mg * Week 3 (Day 15-21), 35.6 mg The Long-Term Dosing Period will begin on Day 22 and will continue until the patient discontinues from the study or the Sponsor elects to terminate the study (i.e., End-of-Study \[EOS\]). An on-site study visit will occur approximately 180 days after Visit 2 on Day 202 (Visit 3). On-site study visits will occur approximately every 6 months and telephone contacts (TCs) approximately every one month in between until the patient withdraws from the study or the study is terminated by the Sponsor. The dose of pitolisant may be adjusted (higher or lower) in increments of 4.45 mg starting at 8.9 mg up to 35.6 mg during the Long-Term Dosing Period based on Investigator assessment of safety/tolerability and effectiveness. All patients will receive safety follow-up TCs from the study site 15 days and 30 days after their final dose of pitolisant, to assess for adverse events (AEs) and concomitant medication use.