Effect of Tegileridine on Postoperative Bowel Function Recovery in Abdominal Surgery

Participants in this arm will receive postoperative analgesia via a Patient-Controlled Intravenous Analgesia (PCIA) pump containing a sterile solution. The pump is filled with a 100 mL mixture of the investigational drug, Tegileridine Fumarate Injection, at a concentration of 0.05 mg/mL, and the adjuvant drug, Dexmedetomidine Hydrochloride Injection, at 2 μg/mL. The PCA pump is programmed with no continuous background infusion (0 mL/h). A loading dose of 20 mL is administered at the start. Thereafter, participants can self-administer a 4 mL bolus on-demand for pain relief, with a maximum allowable dose of 12 mL per hour and a lockout interval of 10 minutes between boluses. This intervention is planned for a duration of 72 hours following abdominal surgery.

Participants in this arm will receive postoperative analgesia via a Patient-Controlled Intravenous Analgesia (PCIA) pump containing a sterile solution. The pump is filled with a 100 mL mixture of the active comparator drug, Morphine Hydrochloride Injection, at a concentration of 0.25 mg/mL, and the same adjuvant drug, Dexmedetomidine Hydrochloride Injection, at 2 μg/mL. The PCA pump parameters are identical to Arm 1: no continuous background infusion (0 mL/h), a 20 mL loading dose, a 4 mL on-demand bolus dose, a maximum limit of 12 mL per hour, and a 10-minute lockout interval. This intervention is also planned for a duration of 72 hours post-surgery. The sole distinction between the two arms is the core analgesic agent (Tegileridine vs. Morphine) within the otherwise identical PCIA regimen.