Intraoperative pain, nausea, vomiting, hypotension, bradycardia are known side effects during
lower abdominal surgery under spinal anesthesia, Time to 2 segment regression of sensory
block and duration of effective analgesia prolonged with intrathecal (IT) 0.4 mg nalbuphine &
IT 0.8 mg nalbuphine, but the incidence of side-effects was significantly higher with IT 0.8
mg nalbuphine compared with (IT) 0.4 mg nalbuphine.