A PhaseⅡ/ Ⅲ Seamless Study to Evaluate Efficacy and Safety of Paracetamol Injection as Adjuvant to Morphine-based Postoperative Analgesia

Inclusion criteria

• Aged from 18 to 70 years inclusively, male or female;
• Patients scheduled for open abdominal surgery(such as gall bladder, lower abdominal investigative surgery), gynecologic surgery(such as trans-abdominal hysterectomy), orthopedic surgery(such as replacement and reconstruction of knee, hip or shoulder joint), with anticipated need for post-operative iv. morphine analgesia≥24h;
• 18kg/m2≤BMI≤30 kg/m2;
• Classified as ASA risk class I, II according to the American Society of Anesthesiologists;
• Able to understand the study procedures and the use of the pain scales, able to operate a patient controlled analgesia (PCA) device and to communicate meaningfully with the study observer and staff;
• Patients free of any contraindication to the study drugs, morphine and to the standardized anesthesia protocol;
• Clearly understand the procedure of study, voluntarily participate and provided written consent form.

Exclusion criteria

• Impaired liver function (ALT and/or AST > 2 x upper limit of normal range, or TBIL≥1.5 x upper limit of normal range);
• Impaired renal function(Serum Creatinine >176μmoL/L), or undergoing dialysis within 28 days before surgery;
• Patients at high risk for bleeding, including congenital hemorrhagic disease(such as Hemophilia), Thrombocytopenia(CBC PLT<30×109/L), Qualitative Plateletdefects(such as ITP, DIC, congenital abonormal platelet), or clinically significant active bleeding;
• Abnormal resting ECG, judged as not eligible for entry by investigator;
• Hypertensive patients not achieving satisfactory BP control under hypertensive medication(Sitting SBP≥160mm Hg, and/or DBP≥105mm Hg during screen period);
• Sitting SBP≤90mm Hg during screening period;
• Diabetic Patients not achieving satisfactory blood glucose control(FBG≥11.1moL/L during screening period);
• Known history of bronchial asthma, pulmonary heart disease or heart failure;
• Participation in other trials within 30 days;
• Pregnant women or women in lactation;
• Patients not eligible due to other reasons judged by the investigator.