Sixty patients with conditions requiring thoracolumbar spine surgery were randomized to receive either ketodex (n=30) or fentanyl (n=30). The primary outcome of interest was the time to first rescue analgesia and the requirement of rescue analgesics in the first 24 hours postoperatively. Secondary outcomes of interest included intraoperative anesthetic requirements, postoperative pain scores, hemodynamic parameters, side effects of the study drugs, and the duration of post-anesthesia care unit stay. Outcomes were assessed up to 24 hours postoperatively. Overall, the results of the study revealed that ketodex significantly prolonged the mean time to first rescue analgesia and reduced the requirement for rescue analgesics compared to fentanyl. The main findings suggest that low-dose ketodex could be a safe substitute for fentanyl infusion, providing prolonged analgesia without opioid-related side effects.