Analgesic Effects of Ketamine, Magnesium Sulfate, and Sodium-Thiopental on Propofol Injection Pain: A Single-Blind Randomized Clinical Trial

Propofol is one of the most frequently used medications for inducing and maintaining anesthesia. However, propofol injection causes pain and discomfort in more than 70% of patients. This study was performed to determine the comparative effects of ketamine, sodium-thiopental, and magnesium sulfate on reducing pain at the onset of anesthesia induced by propofol injection. This single-blind randomized clinical trial was conducted on a population of patients, requiring nonemergency surgeries. The sample size was determined as 25 patients per group. The eligible samples were randomly divided into three groups. An 18-gauge intravenous catheter was inserted in the dorsum of the hand for all patients. Three groups received 0.5 ml/kg of ketamine, 30 mg/kg of magnesium sulfate, and 0.5 ml/kg of sodium-thiopental, respectively. Next, 2.5 mg/kg of propofol 2% was administered at a rate of 1 ml/s. The verbal rating scale (VRS) was applied to assess the severity of pain during injection. According to the results, the prevalence of pain was 36% in the magnesium sulfate group, 16% in the sodium-thiopental group, and 4% in the ketamine group. The ordinal logistic regression test showed that patients from the ketamine group experienced less pain, compared to the magnesium sulfate group (OR, 0.045; P= 0.008). However, no significant difference was observed between the ketamine and sodium-thiopental groups (OR, 0.253; P= 0.283). Ketamine and sodium-thiopental can be effective medications in reducing pain caused by propofol injection. According to the results, magnesium sulfate is not recommended for reducing pain due to propofol injection.