Effect of Tegileridine on Postoperative Bowel Function Recovery in Abdominal Surgery

• Tegileridine (Drug): 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.
• Morphine (Drug): 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.

Primary outcomes

• Proportion of participants with recovery of gastrointestinal function within 72 hours post-surgery. [Within 72 hours after abdominal surgery.]: Gastrointestinal function recovery is defined by the GI-3 composite endpoint: the ability to tolerate solid food (time to first tolerance of solid food) AND having either flatus (time to first flatus) or bowel movement (time to first bowel movement). The proportion is calculated as the number of participants who meet this composite endpoint within 72 hours after surgery divided by the total number of participants analyzed.

Secondary outcomes

• Time to GI-3 recovery. [From end of surgery up to 7 days postoperatively.]: The time (in hours) from the end of surgery until the participant first meets the GI-3 composite endpoint (tolerating solid food AND having flatus or bowel movement).
• Time to first tolerance of solid food. [From end of surgery up to 7 days postoperatively.]: The time (in hours) from the end of surgery until the participant first tolerates solid food.
• Time to first flatus. [From end of surgery up to 7 days postoperatively.]: The time (in hours) from the end of surgery until the participant has the first passage of flatus.
• Overall Benefit of Analgesia Score (OBAS). [At 24, 48, and 72 hours postoperatively.]: The OBAS is a composite score (range 0-28) assessing pain at rest, opioid-related side effects (vomiting, pruritus, sweating, shivering, dizziness), and satisfaction with analgesia. A lower score indicates a higher overall benefit. It will be assessed at 24h, 48h, and 72h postoperatively.
• Quality of Recovery-15 (QoR-15) Score. [At 24 hours postoperatively.]: The QoR-15 is a 15-item patient-reported questionnaire assessing the quality of recovery after anesthesia and surgery. Total scores range from 0 (extremely poor quality of recovery) to 150 (extremely high quality of recovery).
• Time to meet criteria for hospital discharge. [From end of surgery through study completion, an average of 7 days.]: The time (in hours) from the end of surgery until the participant meets the standard discharge criteria of the participating center, as determined by the attending physician.
• Richards-Campbell Sleep Questionnaire (RCSQ) Score. [Daily from postoperative day 1 to postoperative day 3 (assessing the previous night's sleep).]: The RCSQ is a 5-item visual analog scale assessing nighttime sleep quality, including depth of sleep, sleep latency, awakenings, ease of returning to sleep, and overall sleep quality. Each item scores 0-100, and the mean of the five items is the total score, with higher scores indicating better sleep quality.
• Resting pain assessed by Numerical Rating Scale (NRS). [At 24, 48, 72 hours postoperatively]: Pain intensity at rest will be assessed using an 11-point Numerical Rating Scale (NRS), where 0 represents "no pain" and 10 represents "the worst pain imaginable".
• Time to first bowel movement post-operatively. [From end of surgery up to 7 days postoperatively.]: The time (in hours) from the end of the surgical procedure to the patient's first occurrence of a bowel movement.

Sex: All, ages: 18 Years to any

Inclusion Criteria:

1. Scheduled to undergo elective abdominal surgery under general anesthesia.
2. Age ≥ 18 years.
3. Body Mass Index (BMI) between 18 and 30 kg/m².
4. American Society of Anesthesiologists (ASA) physical status classification of I to III.
5. Requires postoperative analgesia and is capable of correctly using a patient-controlled intravenous analgesia (PCIA) pump.
6. Understands the trial objectives and voluntarily participates, providing written informed consent.

Exclusion Criteria:

1. Undergoing gastrointestinal tract surgery.
2. Has advanced cancer with ascites or extensive metastasis, or is receiving systemic chemotherapy/radiotherapy, or requires postoperative hyperthermic intraperitoneal chemotherapy (HIPEC).
3. Diagnosed or suspected gastrointestinal obstruction or emptying disorder.
4. History of severe cardiovascular or cerebrovascular disease (e.g., severe sinus bradycardia, myocardial infarction, unstable angina, grade II or higher atrioventricular block, history of arrhythmia, NYHA class II or higher heart failure, ischemic stroke) or abnormal QTcF interval at screening ( >450 ms for males, >470 ms for females).
5. Comorbid psychiatric or neurological disorders (e.g., schizophrenia, depression, epilepsy) or cognitive dysfunction.
6. Known allergy to opioid drugs or any component of the trial medications.
7. Current acute or chronic pain conditions, or presence of hyperalgesia or other sensory disorders.
8. Long-term opioid therapy (defined as receiving >15 mg morphine milligram equivalents per day for more than 3 days per week, over a period exceeding 1 month within the 12 months prior to surgery).
9. Pregnant or breastfeeding women, or those with a positive pregnancy test at screening or on the day of surgery; or participants (including males) planning for pregnancy.
10. Significant hepatic or renal dysfunction (e.g., ALT/AST > 3 times the upper limit of normal, or requiring renal replacement therapy).
11. Planned admission to the Intensive Care Unit (ICU) for postoperative management.
12. Participation in another interventional clinical trial within the 3 months prior to randomization.
13. Any other condition deemed by the investigator as unsuitable for participation in this trial.

• Zongbin S. Song, M.D., Ph.D., Study director, Xiangya Hospital of Central South University