Rocuronium is given for precurarization, timing or priming before the induction of anesthesia. The incidence of pain on injecting rocuronium is high and can be very distressing. The goal of this study was to evaluate whether pretreating lidocaine, fentanyl, or ondansetron i.v. can decrease the incidence and severity of injection pain.

One hundred and fifty patients were randomly allocated into five groups: patients in groups I, II, III, IV, and V received saline (3 ml), lidocaine 30 mg, lidocaine 50 mg, fentanyl 100 µg, or ondansetron 4 mg after manually occluding the forearm. The occlusion was released and rocuronium 0.6 mg/kg was injected. The patients were then observed and asked whether they had pain in the arm, and responses were assessed.

The mean (median) pain scores in gorups I, II, III, IV, and V were 1.9 (2), 1.0 (1), 0.73 (1), 1.33 (1), and 1.2 (1), respectively. We found that 7%, 37%, 47%, 20%, and 20% of patients in groups I, II, III, IV and V reported no pain. Moderate to severe pain was seen in 60%, 33%, 20%, 40%, and 33% of patients in groups I, II, III, IV, and V, respectively.

Lidocaine, fentanyl, and ondansetron reduced rocuronium injection pain. Of these drugs, lidocaine seems to be the most effective. Fentanyl and ondansetron proved less effective than lidocaine.