Sheryl Crоw is а 38-yeаr-оld wоmаn who presents with recurrent episodes of abdominal cramping associated with intermittent diarrhea. She reports that the abdominal discomfort improves following defecation. After excluding alarm features and other gastrointestinal disorders, she is diagnosed with irritable bowel syndrome with diarrhea (IBS-D). Which antispasmodic medication is most appropriate for the management of her abdominal cramping and intestinal spasms?