The primary objectives of this study are to explore the therapeutic effect of eluxadoline in treating irritable bowel syndrome with diarrhea (IBS-D) in pediatric participants 6-17 years of age, to evaluate the pharmacokinetics of eluxadoline in pediatric participants with IBS-D, and to evaluate the safety and tolerability of eluxadoline in pediatric participants with IBS-D. Enrollment of 12-17 years old age group is closed, enrollment of the 6-11 years old age group will continue.