Premedication with oral paracetamol for reduction of propofol injection pain: a randomized placebo-controlled trial

BackgroundTo compare the effect of premedication with 2 different doses of oral paracetamol to prevent pain at propofol intravenous injection.MethodsWe conducted a double-blind randomized controlled trial in which patients scheduled for induction of general anesthesia with intravenous propofol received either a placebo, 500mg or 1000mg of oral paracetamol (P500 and P1000, respectively) 1h prior to induction. Two mg/kg of propofol was injected at a rate of 600ml/hr. After 1/4 of the full dose had been injected, the syringe pump was paused, and patients were asked to rate pain at the injection site using a verbal numerical rating score (VNRS) from 0 to 10.ResultsThree hundred and twenty-four patients were included. Pain intensity was lower in both P500 and P1000 groups (median VNRS [interquartile range]=2 [0-3] and 4 [2-5], respectively) than in the placebo group (8 [7-10]; P<0.001)*. The rate of pain was lower in the P1000 group (70.4%) than in both the P500 and the placebo group (86.1 and 99.1%, respectively; P<0.001)*. The respective rates of mild (VNRS 1-3), moderate (VNRS 4-6) and severe pain (VNRS 7-10) were 47.2, 23.2 and 0% in the P1000 group, 28.7, 50 and 7.4% in the P500 group, and 0, 22.2 and 76.9% in the placebo group (P<0.001* for between group comparisons). Tolerance was similar in the 3 groups.ConclusionsA premedication with oral paracetamol can dose-dependently reduce pain at propofol intravenous injection. To avoid this common uncomfortable concern for the patients, this well-tolerated, available and cheap treatment appears as an option to be implemented in the current practice.Trial registrationTCTR20150224002. Prospectively registered on 24 February 2015.