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Pain on injection with microemulsion propofol

Ji-Yeon Sim1, Soo-Han Lee, Do-Yang Park

  • 1Department of Anesthesiology and Pain Medicine, Asan Medical Centre, University of Ulsan College of Medicine, Seoul, Korea.

British Journal of Clinical Pharmacology
|February 18, 2009
PubMed
Abstract

Insights

Microemulsion propofol causes more injection pain than lipid emulsion propofol due to higher free propofol concentrations. Pain reduction agents may not work by lowering free propofol levels.

Area of Science:

  • Anesthesiology
  • Pharmacology

Background:

  • Propofol is a widely used anesthetic agent.
  • Injection pain is a common side effect of propofol administration.
  • Different propofol formulations exist, including microemulsion and lipid emulsion.

Purpose of the Study:

  • To compare the incidence and severity of injection pain between microemulsion propofol and lipid emulsion propofol.
  • To investigate the relationship between injection pain, plasma bradykinin generation, and aqueous free propofol concentrations.

Main Methods:

  • 147 patients were evaluated for injection pain.
  • Aqueous free propofol concentrations were measured using high-performance liquid chromatography.
  • Plasma bradykinin concentrations were measured by radioimmunoassays.

Main Results:

  • Microemulsion propofol caused significantly more frequent (69.7% vs 42.3%) and severe injection pain (median VAS 59 mm vs 24 mm) compared to lipid emulsion propofol.
  • Aqueous free propofol concentration was seven times higher in microemulsion propofol.
  • Microemulsion propofol and PEG660 HS increased plasma bradykinin, while lipid emulsion propofol did not.

Conclusions:

  • Higher aqueous free propofol concentrations in microemulsion propofol are associated with increased injection pain.
  • The plasma kallikrein-kinin system may not be the primary mediator of propofol-induced pain.
  • Agents reducing injection pain may not function by decreasing aqueous free propofol concentrations.

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