Objective To study the dosage of preemptive analgesia with Parecoxib and its effect on postoperative pain in patients undergoing laparoscopic cholecystectomy with total intravenenous anesthesia. Methods Ninety-three cases admitted in our hospital from January 2014 to December 2014 were randomly divided into group I(control group), group II treated by drugs for preemptive analgesia and group III treated by drugs for postoperative analgesia with 31 cases in each. The pain degree, plasma substance P,interleuki...