From the FDA Drug Label
Ketamine hydrochloride injection is a clear, colorless sterile solution. ... Dilute ketamine hydrochloride injection with an equal volume of either Sterile Water for injection, USP, 0.9% Sodium Chloride Injection, USP (Normal Saline), or 5% Dextrose in Water.
Maintenance of Anesthesia: To prepare a dilute solution containing 1 mg of ketamine per mL, aseptically transfer 10 mL from a 50 mg per mL vial or 5 mL from a 100 mg per mL vial to 500 mL of 5% Dextrose Injection, USP or 0.9% Sodium Chloride Injection, USP (Normal Saline) and mix well.
The appropriate diluents for ketamine are:
- Sterile Water for injection, USP
- 0.9% Sodium Chloride Injection, USP (Normal Saline)
- 5% Dextrose in Water 1
From the Research
Ketamine should be diluted with normal saline (0.9% sodium chloride) or sterile water for injection when administered intravenously. For adult patients, ketamine can be diluted to a concentration of 1 mg/mL or 10 mg/mL depending on the clinical situation and administration route. When preparing ketamine for IV infusion, a common approach is to add 200 mg (2 mL of 100 mg/mL solution) to 48 mL of normal saline to create a 4 mg/mL solution. Ketamine is compatible with these diluents and maintains stability for 24 hours at room temperature after dilution, as supported by studies such as 2. It's also worth noting that ketamine has been found to be stable over six months of exposure to moderate and high temperature environments, as shown in 3.
Some key considerations when diluting and administering ketamine include:
- Avoid mixing ketamine with barbiturates or diazepam in the same syringe or solution as precipitation may occur.
- Ketamine is physically incompatible with diazepam, midazolam, and many other medications due to its acidic pH (3.5-5.5), which is why it should be administered through a dedicated IV line or thoroughly flushed between medications.
- Always inspect the diluted solution for particulate matter or discoloration before administration.
The stability of ketamine in various solutions and storage conditions has been evaluated in several studies, including 4 and 2, which provide guidance on the safe handling and administration of ketamine. However, the most recent and highest quality study, 3, confirms that ketamine maintains its stability under various conditions, supporting the recommendation for its dilution and administration.