Sulamserod is primarily used in the treatment of irritable bowel syndrome with diarrhea (IBS-D). It functions as a serotonin receptor antagonist, specifically targeting the 5-HT3 receptors in the gastrointestinal tract. By blocking these receptors, it helps to reduce the symptoms associated with IBS-D, such as abdominal pain, discomfort, and frequent bowel movements. This makes it a valuable therapeutic option for patients who struggle with the chronic and often debilitating effects of this condition. Additionally, its targeted action minimizes the risk of side effects commonly associated with broader-acting medications.