https://www.selleckchem.com/products/nvl-655.html Duloxetine has been recently used as a part of multimodal analgesia in perioperative settings, yet the optimal dose of Duloxetine is not determined. A parallel, randomized, placebo-controlled trial. Tertiary level oncology center. 88 female patients with breast cancer were subjected to modified radical mastectomy (MRM) with ASA class I and II were recruited. Participants were randomly allocated into 4 equal groups received 2h preoperatively, placebo (D0, N=22), Duloxetine 30mg (D30, N=22), Duloxetine 60mg (D60, N=22) and Duloxetine 90mg (D90, N=22) tablet. The primary outcome; 24h cumulative postoperative morphine consumption and the secondary outcomes; VAS score of pain intensity, quality of recovery (QoR-40), time to Aldrete 9, and side effects (sedation and vomiting) were measured. The median (IQR) consumption of morphine (mg) in the first postoperative 24h was significantly decreased in both (D60 and D90) groups compared to (D0 and D30) groups, P<0.001(Bonferroni corrected), however, a non-significant reduction was observed between D90 group vs. D60 group and D30 group vs. D0 group, P=0.595 and P=0.462 respectively, D60 vs. D0; 0(0-6) vs. 10(9-12), D60 vs. D30; 0(0-6) vs. 9(8-11), D90 vs. D0; 0(0-5) vs. 10(9-12), D90 vs. D30; 0(0-5) vs. 9(8-11), D90 vs. D60; 0(0-5) vs. 0(0-6), D30 vs. D0; 9(8-11) vs. 10(9-12), patients in D90 group took longer time to recover from anesthesia " time to Aldrete 9" and showed an increased level of sedation in comparison with other groups, vomiting was more frequent in the D90 group. Preoperative oral Duloxetine of 60mg, for patients subjected to MRM is the optimal dose considering its analgesic efficacy and side effects. The trial was registered at Clinical Trials.gov with unique ID number; NCT03468348. The trial was registered at Clinical Trials.gov with unique ID number; NCT03468348. This study aimed to explore the effects of glutamine on hypermetabolic reactions in burned rats an