Fentanyl 5 mg kg-1 and rocuronium bromide 0.6 mg kg-1 were also administered to all patients. Venous blood (10 mL) was collected from each patient at each of the following times: before the beginning of surgery and anesthesia (T1), 2 h after the beginning of surgery (T2), and on the day after the anesthetic-surgical procedure (T3).