Preclusion of pain on injection with propofol: Evaluating the effects of lignocaine or fentanyl pretreatment

BACKGROUND: Propofol (2,6-di-isopropylphenol) used for the induction of anesthesia often causes mild to severe pain or discomfort on injection, for which various methods have been tried, but with conflicting results. OBJECTIVE: The present study involved pretreatment with lignocaine, fentanyl and placebo for prevention of pain on propofol injection to determine the difference in efficacy of fentanyl 100 μg compared with lignocaine 40 mg. MATERIALS AND METHODS: Sixty-three participants of either sex, between 18 and 60 years of age, belonging to ASA physical status 1 and 2, undergoing elective surgery under general anesthesia, were randomized into three equal groups of 21 participants. They received, intravenously, either lignocaine (20 mg/mL) or fentanyl (50 μg/mL) or placebo (normal saline 2 mL) pretreatment before the propofol injection. RESULTS: The three groups were comparable with respect to age, height, weight, sex and ASA physical status. The incidences of pain on pretreatment drug injection was higher in the fentanyl group (33.3%) compared with lignocaine and normal saline (P<0.05). The lowest incidence of pain on propofol injection was observed in the lignocaine pretreatment group (14.3%) compared with fentanyl (42.9%) and normal saline (71.4%) (P<0.05). There was no significant difference in adverse skin reaction within groups. In the normal saline pretreatment group, 38.1% of the participants experienced severe pain, compared with 9.5% in the fentanyl (P<0.05) group; none with lignocaine. The number needed to treat was 2 in the lignocaine pretreatment group compared with 4 in the fentanyl pretreatment group. CONCLUSION: Compared with fentanyl, lignocaine pretreatment was more effective in preventing pain on propofol injection.