Visceral pain following laparoscopic surgery is frequently underestimated, yet it is associated with a range of adverse outcomes. Effective visceral pain management should constitute an essential component of postoperative analgesic strategies following laparoscopic procedures. However, conventional analgesic agents, including μ-opioid receptor agonists, lack specificity for visceral pain. Anrikefon, a novel selective peripheral κ-opioid receptor agonist, demonstrates unique efficacy in alleviating visceral pain with a favorable safety profile. Preliminary studies showed that a single intravenous dose of anrikefon effectively alleviates postoperative pain after abdominal surgery with a low risk of adverse effects. The investigators hypothesize that an appropriate dosing regimen of anrikefon administered via patient-controlled intravenous analgesia (PCIA) pump, as part of a multimodal analgesic strategy, can specifically target and alleviate visceral pain after laparoscopic surgery, thereby achieving comprehensive postoperative analgesia.
Aged >= 18 years but < 75 years;
Scheduled to undergo elective laparoscopic colorectal surgery with an expected duration of >=1 hour;
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.
Presence of preoperative cognitive impairment (Mini-Mental State Examination [MMSE] score < 27), or inability to communicate due to language barrier;
Body mass index (BMI) > 30 kg/m² or < 18 kg/m²;
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;
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;