pms-Ondansetron Description

pms-ONDANSETRON tablets contain either 4 mg or 8 mg of ondansetron base, in the form of ondansetron hydrochloride dihydrate.
Drug Substance: Proper Name: Ondansetron Hydrochloride Dihydrate, USP.
Chemical Name: (±)-1,2,3,9-tetrahydro-9-methyl-3-[(2-methyl-1H-imidazol-1-yl)methyl]-4H-carbazol-4-one, hydrochloride, dihydrate.
Molecular Formula: C₁₈H₁₉N₃O.HCl.2H₂O (hydrochloride dihydrate); C₁₈H₁₉N₃O (base).
Molecular Mass: 365.87 g/mol (hydrochloride dihydrate); 293.4 g/mol (base).
Physicochemical properties: Description and Solubility: Hydrochloride dihydrate: Ondansetron hydrochloride dihydrate is a white to off-white powder. It is soluble at room temperature in either water (~ 32 mg/mL) or normal saline (~ 8 mg/mL) forming a clear and colourless solution. The melting point of ondansetron hydrochloride dihydrate is about 177°C. pKa is 7.4 and pH of 1% w/v solution in water is approximately 4.6. The distribution coefficient between n-octanol and water is pH dependent: log D = 2.2 at a pH of 10.60; log D = 0.6 at a pH of 5.95.
Base: Ondansetron is a white to off-white powder. It is soluble at pH 1.2. Practically insoluble in water. Solubility decreases with increasing pH from very slightly soluble at pH 3.5 and pH 5.4 to practically insoluble at pH 8. Soluble in chloroform and slightly soluble in acetonitrile and methanol.
Excipients/Inactive Ingredients: pms-ONDANSETRON tablets also contain the following excipients (alphabetically): Corn Starch, Croscarmellose Sodium, Lactose, Magnesium Stearate and Microcrystalline Cellulose and a yellow film-coating containing Iron Oxide Yellow, Polyethylene Glycol, Polyvinyl Alcohol, Talc and Titanium Dioxide.