A randomized, double-blind, placebo/positive drug parallel controlled design was used to evaluate the preliminary efficacy and safety of intravenous infusion of LPM3480392 injection using different dosing regimens in subjects with moderate to severe pain after Orthopedic surgery
Voluntarily signed informed consent form (ICF) and comply with the trial procedures before starting the trial-related activities;
Over 18 years old , male or female;
Body mass index (BMI) 18-28 kg/m2 (including the boundary value)；
Subjects who plan to undergo unilateral total knee replacement or unilateral knee ligament reconstruction under general anesthesia; ;
Known history of allergy to any component of the investigational product, or allergy or contraindication to the anesthetic/analgesic drugs used in the study;
History of stroke, cognitive dysfunction, or epilepsy (excluding convulsions caused by previous febrile convulsions in children);
History of difficult airway, such as obstructive sleep apnea syndrome, bronchial asthma, chronic respiratory diseases or other serious respiratory diseases;
Subjects with a history of myocardial infarction, angina pectoris, severe arrhythmia of degree II or above atrioventricular block, or New York Heart Association(NYHA) Class II or above within 6 months prior to screening;
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Treatment groupsSee each treatment group below.