 Patients demographics will be obtained and compared between both groups. The differences in pain scores, morphine consumptions, nauseavomiting scores, and sedation, itching, and patient satisfaction scales will be compared between the two groups with the Student-t test, the analysis of variance, the Fisher exact test, and the Kruskal-Wallis test. The peak vitamin C plasma concentration will be correlated with the pain scores in each group using regression analysis. 