At baseline, patients receive established doses of cholic acid capsules prepared at the Cincinnati Children's Hospital Medical Center Pharmacy. During the study, patients receive the same treatment provided in the to-be-marketed (TBM) cholic acid capsule. Hence, patients serve as their own controls, with baseline values presenting the reference value (CCHMC cholic acid capsule) and values after 30 days treatment presenting the value for the investigational treatment (TBM cholic acid capsule).