A Multicenter, Randomized, Double-Blind, Placebo-Controlled Trial of Intravenous Ibuprofen 400 and 800 mg Every 6 Hours in the Management of Postoperative Pain.

Inclusion Criteria:

• Enrollment was open to patients undergoing scheduled abdominal surgery (intestinal orlower abdomen) or orthopedic surgery (such as knee arthroplasty or shoulder jointreconstruction) under general anesthesia with endotracheal intubation and wereexpected to require patient-controlled intravenous analgesia (PCIA) pump for more than 24h for moderate to severe pain after surgery.

Exclusion Criteria:

• Those who can not understand the NRS score and cooperate with the evaluation; thosewho had head trauma or complicated with organic lesions of the central nervous systemwithin 4 weeks before operation; those who developed coagulation dysfunction or tookanticoagulants and antiplatelet drugs; those with a history of severecardio-cerebrovascular disease, heart failure; those with liver and kidneydysfunction, severe endocrine system diseases, mental illness; those with a history ofpeptic ulcer or bleeding; those who did not control grade 2 or above hypertension orwere still taking two or more of antihypertensive drugs such as angiotensin convertingenzyme inhibitors (ACEI), angiotensin converting enzyme antagonists (ARB) anddiuretics at admission; Increased toxicity due to the interaction of methotrexate,lithium preparations, etc. with the test drug; use of NSAIDs or analgesic musclerelaxants within 24 hours before operation, narcotic dependence or tolerance; allergyto ibuprofen or other NSAIDs; pregnant or lactating women