Stability of Ketamine-Propofol Mixtures for Procedural Sedation and Analgesia in the Emergency Department

Background: The mixture of ketamine and propofol administered together is reportedly an effective agent for procedural sedation and analgesia in the emergency department. However, the physical compatibility and chemical stability of extemporaneous solutions prepared from generic formulations of the drugs are not known. Objective: To investigate the physical compatibility and chemical stability of 50: 50 and 30: 70 mixtures of generic ketamine and propofol packaged in polypropylene syringes and stored at room temperature (23 degrees C) with exposure to light. Methods: Mixtures of ketamine (10 mg/mL) and propofol emulsion (10 mg/mL) were prepared at 50: 50 and 30: 70 ratios, packaged in capped polypropylene syringes (3 syringes for each mixture), and stored at room temperature with exposure to light. One sample from each syringe was analyzed in duplicate at time 0 and after 1 and 3 h. Physical changes such as pH, separation or cracking of the emulsion, change in colour, and formation of gas were monitored. The chemical stability of each drug was assessed by high-performance liquid chromatography Results: Both mixtures of ketamine and propofol were physically compatible during storage for up to 3 h. There were no signs of change in any of the physical parameters during the 3-h study. Each drug retained at least 97% of its original concentration. Conclusion: Mixtures of ketamine and propofol at 50: 50 and 30: 70 ratios were physically compatible and chemically stable for up to 3 h when stored in capped polypropylene syringes at room temperature with exposure to light.