A Study to Evaluate the Efficacy and Safety of Adjunctive KarXT for the Treatment of Mania, With or Without Mixed Features, in Participants With Bipolar-I Disorder Taking Lithium, Valproate, or Lamotrigine

To be considered for this study, you need to be an adult between 18 and 65 years old and have a clear diagnosis of Bipolar-I disorder. You should currently be experiencing a manic episode that started recently (within the last three weeks) and is severe enough to require hospital care. You also need to be taking an ongoing, stable dose of lithium, valproate, or lamotrigine for at least two weeks before joining. If you're on valproate, you should have been taking it for at least seven months.

There are also some reasons why you might not be able to join. For example, if you have other serious mental health conditions diagnosed recently, or if you have a significant problem with substance use (other than tobacco). You also can't take part if there's a serious risk of suicidal thoughts or actions, or if your Body Mass Index (BMI) is outside of a healthy range (between 18 and 40). The full details will be discussed with you by the study team.

If you decide to take part, you would be randomly assigned to receive either the study medication (KarXT) or a placebo (a dummy pill with no active medicine) in addition to your current medication. Neither you nor your doctor would know which one you are receiving. You would have regular visits to the hospital or clinic where doctors and nurses would monitor your health, assess your mood, and check for any side effects. This involves careful mental health evaluations and possibly blood tests or other checks. The study team will explain the full schedule of visits and assessments as well as the total duration of your involvement.