Morphine vs. Oxycodone for Postoperative Pain Management

"At the end of surgery, group 1 will receive intravenous morphine 0.07 mg/kg and intravenous PCA morphine 0.015 mg/kg every time they push the botton with 5 minutes lock-out interval. Maximum 16 mg/2 hours. Group 2 will receive intravenous oxycodone 0.07 mg/kg and intravenous PCA oxycodone 0.015 mg/kg every time they push the botton with 5 minutes lock-out interval. Maximum 16 mg/2 hours.~The patients will use the PCA until the next morning."