6-Hydroxy-(S,S)-Palonosetron is an intermediate used in the synthesis of 6-Oxo-(S,S)-Palonosetron (O858568), which is an impurity of (S,S)-Palonosetron (P165800), a serotonin 5-HT3 receptor antagonist used in the prevention and treatment of chemotherapy-induced nausea and vomiting (CINV). Antiemetic.