The purpose of this study is to assess the efficacy and safety of brenipatide when administered with standard of care (SoC), compared with placebo plus SoC in delaying the worsening of bipolar disorder symptoms. The trial is divided into three periods as follows: Screening period that will last approximately 1 month, treatment period that will last a minimum of 6 months, and the follow up period that will last approximately 2 months. The duration of study participation may vary and may be shortened if bipolar symptoms worsen or if withdrawal from the study occurs for any reason.