 The purpose of the study is evaluate the analgesic efficacy and safety profile of the Cox-2 specific analgesic Etoricoxib arcoxia when administrated pre and postoperatively for controlling pain in adult patients undergoing thyroid surgery. Patients will be followed up in the immediate postoperative period, during the first postoperative POD day and in POD 2, 3 and 7. It is expected that with the addition of Etoricoxib, patients will experience less pain during the overall postoperative period and also a better quality of recovery when compared with the traditional analgesic regimen. 