The purpose of this study is to evaluate the effect of an investigational medication compared to a placebo on itching in children with Alagille Syndrome. Alagille Syndrome is a genetic disorder that affects the liver, heart, and other parts of the body and can cause itching due to liver problems.

Participants will receive either the investigational medication or a placebo, which is an inactive substance that looks like the investigational medication but does not contain any medicine. The study will assess changes in itching, serum bile acids, liver enzymes, and other biochemical markers related to cholestatic liver disease over a 13-week period.

• Who can participate: Children aged 2 to 18 years with a diagnosis of Alagille Syndrome experiencing moderate to severe itching are eligible to participate. Key eligibility factors include stable liver function and no recent participation in other clinical trials.
• Study details: Participants will take the investigational medication or placebo daily to see how it affects itching and various liver-related markers.
• Study Timelines: The study will last 13 weeks.