ondansetron pretreatment reduces pain on injection of propofol

to assess the effectiveness of ondansetron pretreatment in alleviating propofol injection pain, 135 patients were randomly assigned to one of following three groups. group 1 who received up to 2 ml pretreatment 50 mg tramadol in the saline, group 2 cases who received up to 2 ml pretreatment 4 mg ondansetron in saline, and group 3 who received up to 2 ml solution saline. a 20 gauge cannula was placed into the largest vein on the dorsum of the hand. tourniquet was closed to the arm above the cannula and inflates to 70 mmhg, and then drug was injected. after 20 seconds, the tourniquet deflated, and propofol 2mg/kg injected over 10 seconds and pain assessment was made. results: tramadol and ondansetron significantly reduced the incidence and severity of propofol injection pain more than placebo (p=0.001). the efficacy of ondansetron in alleviating the pain on injection of propofol was no different from tramadol (p=0.330). ondansetron pretreatment may be used to reduce the incidence of pain on injection of propofol, an advantage added to the useful prevention of postoperative nausea and vomiting.