Background: Anesthesiologists are responsible for the development of pain services in the current era. Hence ideal adjuvants that can be used with bupi- vacaine for stable intraoperative conditions and prolonging the postoperative analgesia with fewer side effects are being investigated. Opioids, despite use- ful as adjuvants, are associated with undesirable side effects. Aim of the work: The study was done to compare analgesic efficacy and hemodynamic of intrathecal injection of bupivacaine alone or with fentanyl, clonidine, and neostigmine in lower abdominal surgeries, over the first 24 postoperative hours, in a randomized, double-blind, and clinical trial. Methods: 100 Pa- tients were randomized into four equal groups, 25 patients in each group; Group B patients received 2.5 ml of 0.5% hyperbaric bupivacaine and 0.5 ml of normal saline. Group BF patients received 2.5 ml of 0.5% hyperbaric bupi- vacaine with (25 mics) of fentanyl. Group BC patients received 2.5 ml of 0.5% hyperbaric bupivacaine with 0.5 ml (75 mics) of clonidine. Group BN patients received 2.5 ml of 0.5% hyperbaric bupivacaine with 0.1 ml of neostigmine (50 mics) and 0.4 ml of normal saline. Intrathecal anesthesia was done with a recording of parameters intraoperative and the post-operative period. Each patient was assessed for hemodynamic parameters and effective analgesia in operation, and presence of complications (nausea, vomiting, sedation and pruritus) visual analogue pain score (VAS) postoperatively by a blinded in- vestigator in the post-anesthesia care unit (PACU) and at 1, 2, 3, 4, 8 12, 18 and 24 h postoperatively. Results: The postoperative analgesia is more effec- tive with group BC (the gold standard) than group B, group BF, and group BN. As regard complications during the study in all groups, complications as nausea, and vomiting were mainly with group BN; hypotension was primarily in group BC. Conclusion: Bupivacaine clonidine, bupivacaine neostigmine, and bupivacaine fentanyl intrathecal anesthesia produced a longer duration
of postoperative analgesia after lower abdominal surgery in patients than bu- pivacaine alone. Bupivacaine clonidine mixture had the most extended period of analgesia, but with hypotension. So bupivacaine fentanyl mixture with moderate duration of analgesia and minimal side effects is most safe for a pa- tient.