Anrikefon Injection for Postoperative Analgesia in Thoracoscopic Lung Surgery: A Randomized, Double-Blind, Active-Controlled, Parallel-Group, Single-Center Clinical Study

Inclusion criteria

• Age 18 to 85 years (inclusive), either sex.
• Body mass index (BMI) 18.0 to 30.0 kg/m² (inclusive).
• American Society of Anesthesiologists (ASA) physical status Class I to III preoperatively.
• Undergoing elective thoracoscopic lung surgery under general anesthesia (complete video-assisted thoracoscopic surgery, without conversion to thoracotomy), with successful recovery from anesthesia within 1 hour postoperatively, fully awake, able to accurately complete NRS scoring with an NRS score ≥ 4, and willing to accept the analgesic regimen defined in the study protocol.
• Able to understand the purpose, procedures, and scale scoring methods of the study, capable of operating the PCA device, and able to communicate effectively with investigators.
• Voluntarily participating and providing written informed consent.

Exclusion criteria

• Known or suspected allergy or contraindication to any of the study drugs.
• History of opioid abuse, drug or alcohol dependence, or current preoperative use of opioids.
• Use of analgesic medications (acetaminophen, NSAIDs, opioids, tramadol, etc.) within 24 hours preoperatively.
• Uncontrolled severe cardiovascular disease (second-degree or higher atrioventricular block, resting heart rate < 50 bpm, uncontrolled hypertension, myocardial infarction or unstable angina within the past 6 months), hepatic insufficiency (ALT/AST > 2× upper limit of normal), renal insufficiency (eGFR < 30 mL/min/1.73m² or maintenance dialysis), neuropsychiatric dysfunction, or inability to cooperate with pain assessment.
• History of chronic pain.
• Severe respiratory or circulatory failure during anesthesia/surgery (including intraoperative conversion to thoracotomy, operative time > 6 hours, or intraoperative hemorrhage > 1000 mL).
• Pregnancy or lactation, or positive urine pregnancy test in women of childbearing potential.
• Participation in another drug/device clinical trial within 30 days before randomization.
• Any other condition that the investigator deems unsuitable for participation.