Safety and Tolerability of Controlled-release Oxycodone on Postoperative Pain in Oncologic Head and Neck Surgery

Inclusion Criteria: * patients on postoperative head and neck oncologic surgery * 2 and 3 American Society of Anesthesiologists physical status * moderate to severe postoperative pain * elective surgery * able to swallow tablets whole (not chewed, broken or crushed) in the immediate postoperative period after recovery of cognitive functions. Exclusion Criteria: * pregnant or breastfeeding * allergic to oxycodone and other opioids * gastrectomized or colostomized * asthmatics with severe organ dysfunction * history or suspected paralytic ileus * history psychiatric disorders * severe respiratory depression * patients who are receiving opioid analgesics in baseline * history of abuse of alcohol and illicit drugs * plasma glutamic oxaloacetic transaminase above 48 U / l (men) and 40 U / I (women) and / or glutamic pyruvic transaminase above 53 U / l (men) and 40 U / I (women) * plasma creatinine above 1.7 mg / dl and / or urea above 65 mg / dl * emergency surgery