Ondansetron hydrochloride is available in 20-mL multiple-dose vials and 2-mL single-dose vials.2836; 2837 Each mL of solution in multiple-dose vials contains ondansetron (as the hydrochloride dihydrate) 2 mg with sodium chloride 8.3 mg, citric acid monohydrate 0.5 mg, sodium citrate dihydrate 0.25 mg, methylparaben 1.2 mg, and propylparaben 0.15 mg in water for injection.2836; 2837 Each mL of solution in single-dose vials contains ondansetron (as the hydrochloride dihydrate) 2 mg with sodium chloride 9 mg, citric acid monohydrate 0.5 mg, and sodium citrate dihydrate 0.25 mg in water for injection.2836
pH
Trade Name(s)
Zofran
Ondansetron hydrochloride is administered as an intravenous infusion over 15 minutes, as a direct intravenous injection, or intramuscularly.2836 For intravenous infusion, ondansetron hydrochloride is administered after further dilution with 50 mL of sodium chloride 0.9% or dextrose 5%.2836; 2837 For intravenous infusion in pediatric patients 6 months to 1 year of age and/or weighing 10 kg or less, ondansetron hydrochloride may be diluted in 10 to 50 mL of sodium chloride 0.9% or dextrose 5%.2836; 2837
For direct intravenous injection, ondansetron hydrochloride is administered undiluted over at least 30 seconds and preferably over 2 to 5 minutes.2836; 2837
For intramuscular injection, ondansetron hydrochloride is administered undiluted.2836; 2837
Ondansetron hydrochloride is a clear, colorless solution.2836; 2837 Intact vials should be stored at controlled room temperature and protected from light.2836; 2837 Alternatively, some manufacturers state that intact vials may be stored under refrigeration.2836 Although ondansetron hydrochloride is unstable under intense light, it is stable for about 1 month in daylight with added fluorescent light.1366 Ondansetron occasionally may precipitate at the stopper/vial interface in vials that are stored upright; the potency and safety of ondansetron are not affected.2836; 2837 If a precipitate is observed, the drug may be resolubilized by vigorously shaking the vial.2836; 2837
Manufacturers state that diluted solutions for infusion in sodium chloride 0.9% or dextrose 5% should not be used beyond 24 hours;2836; 2837 however, diluted solutions of ondansetron hydrochloride are stated to be stable for 48 hours at room temperature in light when diluted in sodium chloride 0.9%, dextrose 5%, dextrose 5% in sodium chloride 0.45%, dextrose 5% in sodium chloride 0.9%, or sodium chloride 3%.2836; 2837
Ondansetron hydrochloride (Glaxo) 0.03 and 0.3 mg/mL in dextrose 5% or sodium chloride 0.9% was stable when frozen at -20°C, exhibiting a 10% or less loss in 3 months.1642
pH Effects
The natural pH of ondansetron hydrochloride solutions is about 4.5 to 4.6.1366; 1367 The pH of commercially available ondansetron solution has been adjusted with citric acid monohydrate and sodium citrate dihydrate to the range of 3.3 to 4.2836; 2837 If the pH is increased, a precipitate of ondansetron free base has been reported to develop at pH 5.71366 and pH 7.1513 Redissolution of the ondansetron precipitate occurs at pH 6.2 when titrated with hydrochloric acid.1513 Precipitation by combination with alkaline drugs has been observed.1365; 1513
Syringes
The stability of ondansetron hydrochloride undiluted at an ondansetron concentration of 2 mg/mL and diluted in dextrose 5% and sodium chloride 0.9% at ondansetron concentrations of 1, 0.5, and 0.25 mg/mL and packaged in polypropylene syringes was reported. Representative syringes were stored at 24°C for 48 hours, 4°C for 14 days, and frozen at -20°C for 90 days. Visually, the solutions exhibited no precipitate or color or clarity changes. Ondansetron concentrations in all samples remained above 90%; most samples were above 95%. Sequentially storing sample syringes for 90 days at -20°C followed by 14 days at 4°C followed by 48 hours at 24°C did not alter the stability.2056
When diluted with compatible infusion solutions, ondansetron hydrochloride is stable for up to 7 days at room temperature or under refrigeration in Plastipak syringes with syringe caps.1366
Filtration
Ondansetron hydrochloride (Glaxo) prepared at ondansetron concentrations of 0.03 and 0.2 mg/mL (30 and 200 mcg/mL) in sodium chloride 0.9% was delivered over 15 minutes through 5 different 0.2-µm inline filters: Continu-Flo Solution Set (Baxter, 2C5561S), Filtered Extension Sets (Burron, PFE-2007 and FE-2024), Universal Primary infusion set (IVAC, 52023), and Ivex-HP Filterset-SL (Abbott, 4524). Little or no ondansetron loss was found.1678
Central Venous Catheter
Ondansetron hydrochloride (Glaxo Wellcome) prepared at an ondansetron concentration of 0.2 mg/mL in dextrose 5% was found to be compatible with the ARROWg+ard Blue Plus (Arrow International) chlorhexidine-bearing triple-lumen central catheter. Essentially complete delivery of the drug was found with little or no drug loss occurring. Furthermore, chlorhexidine delivered from the catheter remained at trace amounts with no substantial increase due to the delivery of the drug through the catheter.2335
For a list of references cited in the text of this monograph, search the monograph titled References.