a comparison of premedication injections of magnesium sulfate, ketamine and lidocaine on the severity of pain induced by intravenous injection of propofol

The pain induced by intravenous injection of propofol is controlled using a variety of methods, but there is no consensus in choosing the best effective method. therefore, this study was conducted to compare premedication injections of magnesium sulfate, ketamine and lidocaine on pain induced by intravenous injection of propofol. the present double-blind clinical trial was conducted on 150 patients with elective orthopedic surgery under general anesthesia. the patients were randomly assigned into three groups of 50; group i: 2 cc magnesium sulfate 20%, group ii: 2 cc ketamine at a dose of 0.1mg/kg and group iii: 2 cc lidocaine 2% at a dose of 0.05mg/kg. one minute after injecting the drugs, 2mg/kg intravenous propofol was injected in all groups and then a trained unaware expert evaluated the severity of subsequent pain using a numeric pain rating scale. the mean age of the patients was 39.3±12.3 years, and the mean weight was 67.4±11.5 kg. the patients consisted of 98 (65.4%) males and 52 (34.6%) females. ten in the group magnesium sulfate, eight in the group ketamine and seven in the group lidocaine complained of pain. the mean pain severity was 0.85±0.38 in the group magnesium sulfate, 0.66±0.26 in the group ketamine and 0.62±0.22 in the group lidocaine (p=0.513). the group lidocaine showed further pain relief compared to other two groups, but there was no statistically significant difference.