Intravenous injection of rocuronium produces intense discomfort at the site of injection in conscious patients. The aim of this study was to compare the effects of intravenous ondansetron, lidocaine, and tramadol for minimizing pain caused by the injection of rocuronium.

One hundred twenty patients were randomly assigned four groups. Before general anesthesia was induced with thiopental sodium (5 mg/kg), manual occlusion (70 mmHg) with tourniquet of venous inflow was performed. The patients were given saline 4 ml (Group 1, n = 30), ondansetron 8 mg (Group 2, n = 30), lidocaine 60 mg (Group 3, n = 30), or tramadol 50 mg (Group 4, n = 30) diluted into a 4 ml solution. The occlusion was released after 20 seconds and rocuronium was injected over 10 15 seconds. The patients were asked immediately if they had pain in the arm, and the response was assessed. The pain response to rocuronium injection was graded with using Memis' 4-point scale. The side effects were recorded for 24 hours after administration of rocuronium.

There were no difference among groups in respect of age, weight, and gender (P < 0.05). Lidocaine reduced the incidence of rocuronium injection pain but ondansetron and tramadol did not (P < 0.05). Ondansetron, lidocaine, and tramadol reduced the severity of rocuronium injection pain (P < 0.05).

I conclude that lidocaine is the most effective among these drugs in the prevention of rocuronium injection pain.