Synonyms: Ondansetron Hydrochloride Dihydrate Imp. C (EP), Ondansetron Imp. C (EP), Ondansetron USP Related Compound C, Ondansetron USP RC C, 9-Methyl-1,2,3,9-tetrahydro-4H-carbazol-4-one, GR 36948X, USP Ondanestron Related Compound C, Ph Eur Ondansetron Impurity C, methyl carbazolone (GR 36948X), Ondansetron Related Compound C, Ondansetron Hydrochloride Dihydrate Impurity C, Ondansetron Impurity C