Safety and Efficacy Study of Ramelteon (TAK-375) Tablets for Sublingual Administration (SL) in Adults With 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 depression in people who take Ramelteon as a sub-lingual formulation. This study plans to enroll a minimum of 276 participants and a maximum of up to approximately 870 participants 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 study plans to conduct one unblinded interim analysis after the first 276 subjects have been enrolled and treated for the 6-week double-blind treatment period. Based on the interim analysis, the study plans to adapt limited aspects of the design including: 1) to make no changes to the study; 2) to reassess sample size based on the interim analysis results. This multi-centre trial will be conducted in North America and Europe. The overall time to participate in this study is up to 14 weeks. Participants will make 8 visits to the clinic, and will be contacted by telephone 30 days after last dose of study drug for a follow-up assessment. An independent Data Monitoring Committee (DMC) recently performed a planned interim analysis of efficacy and safety data from this study. Upon completion of their review, the DMC advised that the unblinded interim data met the predefined efficacy criteria for study termination. No safety concerns were identified.