The active ingredient of Ondansetron Injection, USP is ondansetron hydrochloride, a selective blocking agent of the serotonin 5-HT3 receptor type. Its chemical name is (±) 1, 2, 3, 9 tetrahydro-9-methyl-3-[(2-methyl-1H-imidazol-1-yl)methyl]-4H-carbazol-4-one, monohydrochloride, dihydrate. It has the following structural formula:
The empirical formula is C18H19N3O∙HCl∙2H2O, representing a molecular weight of 365.9 g/mol.
Ondansetron HCl is a white to off-white powder that is soluble in water and normal saline.
Each 1 mL of aqueous solution in the 2-mL single-dose vial contains 2 mg of ondansetron as the hydrochloride dihydrate; 9 mg of sodium chloride, USP; and 0.46 mg of citric acid anhydrous, USP and 0.25 mg of sodium citrate dihydrate, USP as buffers in Water for Injection, USP.
Each 1 mL of aqueous solution in the 20 mL multiple-dose vial contains 2 mg of ondansetron as the hydrochloride dihydrate; 8.3 mg of sodium chloride, USP; 0.46 mg of citric acid anhydrous, USP and 0.25 mg of sodium citrate dihydrate, USP as buffers; and 1.2 mg of methylparaben, NF and 0.15 mg of propylparaben, NF as preservatives in Water for Injection, USP.
Ondansetron Injection, USP is a clear, colorless, nonpyrogenic, sterile solution for intravenous or intramuscular use. The pH of the injection solution is 3.3 to 4.0.