The Changes of Propofol Concentration with Time-Course in the
Lidocaine-Propofol or Ketamine-Propofol Mixtures
Ho-Yeong Kil, M.D., Bong-Soo Chae, M.D. and Dae-Woo Kim, M.D.*
Department of Anesthesiology, College of Medicine, Hallym University and
Korea Catholic University,* Seoul, Korea
Background: Propofol is widely used for induction and maintenance of anesthesia, but pain on injection is one of the sujective source of patient unsatisfaction. Of the methods, pretreatment or addition of lidocaine or ketamine have been reported to reduce pain on injection. But it is not yet known that stability of propofol following the addition of lidocaine or ketamine.
Methods: After mixing 9 ml of propofol(1%) and 0, 5, 10, 15, 20 mg of lidocaine(2%) or 10, 20 mg of ketamine, the sample(0.9ml) were divided into 10 glass vials and stored at room temperature. Macroscopic changes, microscopic changes, and propofol concentrations were measured at 0, 15, 30 min, every 1hr for 6 hrs, and at 24 hr.
Fig 1. Changes of Propofol Concentration after mixing of Lidocaine
Conclusions: Lidocaine(more than 15 mg), but not ketamine, added to 90 mg of propofol reduced propofol concentration significantly and showed microscopic change after 1hr. So, this mixtures seems to be inappropriate for longterm storage and thus ketamine-propofol mixtures are more appropriate for this purpose.
References: Lilley EMM, Isert PR, Carasso ML, Kennedy RA: The effect of the addition of lignocaine on propofol emulsion stability. Anaesthesia 1996; 51: 815-8.