Intrathecal Nalbuphine Versus Other Opioids as Adjuvant to 0.5% Hyperbaric Bupivacaine in Caesarean Section: A Systematic Review and Meta-Analysis

Background/Objectives: Subarachnoid anaesthesia is widely preferred for caesarean delivery due to its rapid onset, reliability, and safety. The addition of adjuvants to intrathecal hyperbaric bupivacaine has been shown to enhance the quality of anaesthesia and prolong postoperative analgesia. Opioids are among the most frequently used intrathecal adjuvants; however, their administration is associated with adverse effects. Nalbuphine, a mixed opioid agonist–antagonist, may be a promising agent for obstetric use due to its favourable pharmacodynamic properties. This study aimed to systematically review and, where feasible, meta-analyse the evidence comparing nalbuphine with other intrathecal opioid adjuvants to hyperbaric bupivacaine 0.5% for caesarean section, with a primary focus on efficacy and safety. Methods: A systematic review and meta-analysis of controlled trials was conducted. Web of Science Core Collection, MEDLINE (PubMed), Scopus, the Library of Congress, and LISTA (EBSCO) were systematically searched to identify eligible studies. Pooled mean difference (MD) and risk ratio (RR) were calculated using random-effects model. Results: Ten studies encompassing 1095 parturients were included. Compared with fentanyl, intrathecal nalbuphine was associated with a modest prolongation of effective analgesia. However, this finding was accompanied by substantial heterogeneity and very low certainty of evidence. In contrast, morphine provided a longer duration of analgesia than nalbuphine. Overall, nalbuphine and fentanyl demonstrated comparable block characteristics, with only minimal and clinically insignificant differences in onset and duration. Importantly, nalbuphine was associated with fewer adverse effects, particularly shivering and PONV. Conclusions: Subarachnoid nalbuphine may serve as a potential alternative adjuvant to 0.5% hyperbaric bupivacaine in caesarean section anaesthesia. It may provide an analgesic efficacy comparable to fentanyl and, although less potent than morphine, it may demonstrate a more favourable safety profile.