Can a pill stop the relentless itch of a liver disease? a major trial aims to find out.

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Male and female participants must be between 18 to 80 years of age inclusive, at the time of signing the informed consent. * Participants who have documented PBC. * Participants who have moderate to severe itch. Exclusion Criteria: * Total bilirubin \>2.0 times Upper Limit of Normal (ULN) using the average of two Baseline measures. * Screening Alanine Aminotransferase (ALT) \> 6 times ULN in a single Baseline measure or ALT \> 5 times ULN using the average of two Baseline measures. * Screening estimated glomerular filtration rate (eGFR) \<30 milliliter per minute per 1.73 square meter (mL/min/1.73m\^2). * History or presence of hepatic decompensation (e.g., variceal bleeding, hepatic encephalopathy or ascites). * Presence of HBsAg positive hepatitis B or hepatitis C (HCV) (anti-HCV and Ribonucleic acid \[RNA\] detected) infection, primary sclerosing cholangitis (PSC), alcoholic liver disease and/or confirmed hepatocellular carcinoma or biliary cancer. * Current clinically significant diarrhea or active inflammatory ileal disease according to Investigator´s clinical judgment. * Current symptomatic cholelithiasis or cholecystitis. * Current diagnosis of primary skin disorders with itch as a characteristic feature (e.g., atopic dermatitis, psoriasis). * Primary sleep disorders such as but are not limited to sleep apnea, narcolepsy, hypersomnia. * Initiation, discontinuation or change in dose of ursodeoxycholic acid (UDCA), bezafibrate or fenofibrate in the 8 weeks prior to Screening. * Use of obeticholic acid: within 8 weeks prior to Screening. (Participants may not initiate or restart during the study). * Initiation, discontinuation, or change in dose of any of the following in the 8 weeks prior to Screening: bile acid binding resins, rifampicin, naltrexone, naloxone, nalfurafine, pregabalin, gabapentin, sertraline or other selective serotonin reuptake inhibitor (SSRIs), antihistamines used for the treatment of itching. * Administration of any other human ileal bile acid transporter (IBAT) inhibitor in the 12 weeks prior to screening. * Any planned procedures intended to treat cholestatic pruritus such as nasobiliary drainage or ultraviolet light therapy from Screening and throughout the study. * History of sensitivity or intolerance to the study treatment.