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 preparing it for intravenous administration. For most clinical applications, ketamine can be diluted to a concentration of 1-10 mg/mL depending on the desired dose and administration rate. When preparing ketamine for continuous infusion, it is typically diluted in normal saline to a concentration of 1-2 mg/mL. It's essential to note that ketamine is physically compatible with most common IV fluids, but normal saline is the preferred diluent in most clinical settings. Ketamine should not be mixed in the same syringe with barbiturates or diazepam as precipitation may occur. Once diluted, ketamine solutions should be used promptly, though they remain stable for 24 hours at room temperature. The pH of ketamine is acidic (3.5-5.5), which explains why it cannot be mixed with alkaline solutions. Always check the solution for clarity and absence of particulate matter before administration.
Some key points to consider when diluting ketamine include:
- The stability of ketamine in various environments, as studied in 2, which found that ketamine samples exhibited limited degradation after 6 months of exposure to real-world and simulated extreme high-temperature environments.
- The compatibility of ketamine with other medications, such as hydromorphone, as studied in 3, which found that mixtures of hydromorphone and ketamine were stable for up to 7 days at 25°C.
- The importance of using the correct diluent, as normal saline is the preferred diluent in most clinical settings, to ensure the stability and efficacy of ketamine.
In terms of the specific dilution ratio, it is generally recommended to dilute ketamine to a concentration of 1-10 mg/mL, depending on the desired dose and administration rate. However, the exact dilution ratio may vary depending on the specific clinical application and the patient's individual needs. It is always best to consult the manufacturer's instructions and relevant clinical guidelines, such as those provided in 4, 5, and 6, for specific guidance on the use and dilution of ketamine.