Effects and safety of magnesium sulfate on propofol-induced injection pain, a meta-analysis of randomized controlled trials

Background: Propofol is the most widely used drug in the induction of general anesthesia, however its disadvantages of injection pain has always been a problem for clinical anesthetists. Many strategies have been proposed and magnesium sulfate is one of them. This is the first meta-analysis studies evaluating effects of magnesium sulfate pretreatment for preventing propofol-induced injection pain. Methods: We searched MEDLINE, EMBASE, Google scholar and the Cochrane Database of Systematic Review databases for randomized controlled trials (RCTs) that evaluated the prophylactic effect of magnesium sulfate on propofol injection pain. Meta-analyses were performed using RevMan 5.3 software. Results: Five RCTs involving 545 participants were included. Magnesium sulfate allows more patients experiencing no pain or mild pain during propofol injection ([RR] 2.70, 95% [CI] 1.10-6.64, P=0.03, 2.12,95% CI 1.46-3.08, P < 0.0001, respectively). And the number of patients with severe pain (RR 0.12, 95% CI 0.06-0.25, P < 0.00001) on injecting propofol were significantly decreased. However, no statistical significance was found between magnesium sulfate group and placebo group in moderate pain (RR 0.22, 95% CI 0.05-0.97, P=0.05). Conclusion: Our meta-analysis suggested that pretreatment with magnesium sulfate intravenously before injecting propofol allow more patients to experiencing no pain during propofol injection and can reduce the intensity of injection pain effectively without causing any adverse effect.