New drug aims to ease hidden pain after keyhole surgery

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Aged \>= 18 years but \< 75 years; 2. Scheduled to undergo elective laparoscopic colorectal surgery with an expected duration of \>=1 hour; 3. The incisional pain can be covered by the transversus abdominis plane block or rectus sheath block; yet patients still require postoperative patient-controlled intravenous analgesia. Exclusion Criteria: 1. Presence of preoperative cognitive impairment (Mini-Mental State Examination \[MMSE\] score \< 27), or inability to communicate due to language barrier; 2. Body mass index (BMI) \> 30 kg/m² or \< 18 kg/m²; 3. Presence of poorly controlled or untreated comorbidities, including but not limited to the following: hypertension characterized by a resting systolic blood pressure (SBP) \> 180 mmHg and/or diastolic blood pressure (DBP) \> 110 mmHg, coronary artery disease with unstable angina or myocardial infarction within 6 months, heart failure rated as New York Heart Association classification \>= III, severe chronic obstructive pulmonary disease (or in a state of acute exacerbation), severe hepatic insufficiency (Child-Pugh grade C), severe renal insufficiency (estimated glomerular filtration rate \< 30 ml/min/1.73m²), or American Society of Anesthesiologists (ASA) physical status classification \>= IV; 4. Continuous use of opioid analgesics for more than 10 days for any reason, or alcohol abuse (average daily intake of pure alcohol \> 36 g) within 3 months before screening; 5. Preoperative use of opioid or non-opioid analgesics with the interval between the last administration and randomization shorter than five half-lives of the drug or the duration of drug action (whichever is longer); 6. Known allergies or contraindications to opiates or other medications that may be used in this study, such as anesthetics, antiemetics, and nonsteroidal anti-inflammatory drugs (NSAIDs); 7. Anticipated need for postoperative mechanical ventilation； 8. Other conditions that are considered unsuitable for study participation.