Pain on i.v. injection of propofol (ICI 35 868) in emulsion formulation. Short communication.

Pain on injection of three anaesthetic induction agents, thiopentone, methohexitone and propofol (diisopropyl phenol), administered into a vein on the dorsum of the hand or wrist, was studied in 32 premedicated patients undergoing elective surgery. The pain was rated as none, mild or severe. A 1% emulsion formulation of propofol (ICI 35 868) (2 mg kg-1) and methohexitone (2 mg kg-1) induced pain significantly more often, in 100% and 80% of patients, respectively, than thiopentone (4 mg kg-1), 0%. The pain was rated as severe more often in patients receiving propofol (67%, P less than 0.01 vs thiopentone) than in those anaesthetized with methohexitone (20%) or thiopentone (0%). It is concluded that the fat emulsion form of propofol, when injected into a peripheral vein, frequently induces severe pain.