Efficacy of Fentanyl versus Nalbuphine as Adjuvant agents in the induction phase of general anesthesia: A Comparative Study

Abstract

Background: Propofol is the most commonly preferred intravenous induction agent but may cause dose-dependent cardiovascular depression. Opioid premedication reduces propofol requirements during induction. This study compared the propofol-sparing efficacy of fentanyl and nalbuphine during induction of general anaesthesia. Methods: In this prospective comparative study, 100 ASA physical status I–II adults undergoing elective surgery under general anaesthesia were randomized into two groups (n=50 each). Group F received intravenous fentanyl 3 μg/kg and Group N received intravenous nalbuphine 0.3 mg/kg six minutes before induction. Using propofol titrated to loss of the eyelash reflex. Primary outcomes were before propofol dose, Ramsay Sedation Scale score, and induction time. Secondary outcomes included haemodynamic changes and opioid-related adverse effects. Results: Fentanyl significantly reduced the propofol dose required for induction compared with nalbuphine 80.78 ± 14.30 mg vs 95.44 ± 15.69 mg (p < 0.001). Ramsay Sedation Scale scores were higher with nalbuphine 2.34 ± 0.35 vs 2.87 ± 0.56 (p < 0.001). Induction time was significantly shorter in the fentanyl group 43.52 ± 8.53 s vs 48.76 ± 10.24 s (p = 0.007). The incidences of hypotension, bradycardia, respiratory depression, postoperative nausea and vomiting, and pruritus were low and comparable between groups. Conclusion: Fentanyl demonstrated superior propofol-sparing efficacy compared with nalbuphine while maintaining comparable haemodynamic stability and safety. Nalbuphine produced greater pre-induction sedation and represents a suitable alternative opioid adjunct.