This study is looking at the long-term safety and how well people can handle taking KarXT and KarX-EC. These medicines are being tested for treating Schizophrenia and autism-related irritability in teenagers. Schizophrenia is a mental disorder that affects how a person thinks and feels, while autism-related irritability refers to the frustration or anger sometimes seen in people with autism. The study is for those who have already finished another study without any serious side effects. People who have a high risk of hurting themselves or others cannot join. It is also important for participants to have normal blood pressure and no major health issues.

• The study is for teens who have completed a related study without bad side effects.
• Participants must not have serious health problems or high blood pressure.
• Those who might harm themselves or others cannot join.