A Safety and Efficacy Study of Ramelteon Tablets for Sublingual Administration (TAK-375SL) in the Maintenance Treatment of Bipolar 1 Disorder

The drug being tested in this study is called Ramelteon. Ramelteon is being tested to treat people who have Bipolar 1 Disorder. This study will look at the symptoms of bipolar disorder in people who take Ramelteon. The study will enroll approximately 495 patients. Participants will be randomly assigned (by chance, like flipping a coin) to one of the three treatment groups-which will remain undisclosed to the patient and study doctor during the study (unless there is an urgent medical need): * Ramelteon (Dose 1) * Ramelteon (Dose 2) * Placebo (dummy inactive pill) - this is a tablet that looks like the study drug but has no active ingredient All participants will be asked to take one tablet every night at bedtime throughout the study. This multi-centre trial will be conducted in North America and Europe. The overall time to participate in this study is 13 months. Participants will make 17 visits to the clinic, and will be contacted by telephone 30 days after last dose of study drug for a follow-up assessment. This 12-month study was designed to evaluate the efficacy of TAK-375SL in the maintenance treatment of bipolar 1 disorder. At this time, Takeda has decided to withdraw the study for business reasons. No participants were enrolled in this study.