Ondansetron Hydrochloride Dihydrate is the dihydrate form of the hydrochloride salt of ondansetron, a selective 5-HT₃ receptor antagonist. It serves as a key active pharmaceutical ingredient (API) for antiemetic drugs used to prevent nausea and vomiting associated with chemotherapy, radiation therapy, and postoperative recovery. The compound acts by blocking 5-HT₃ serotonin receptors in the central nervous system and gastrointestinal tract. This high-purity reagent (≥98% by HPLC) is ideal for pharmaceutical research, development, and manufacturing applications.