Brief Summary: The role of a single-dose intraoperative methadone on postoperative pain and opioid consumption in patients undergoing Surgeon Accuracy Robot Assistant cystectomy. A prospective double-blind, randomized controlled trial investigating the effect of a single-dose of intraoperative methadone in patients undergoing robotassisted cystectomy.

Detailed Description: During early recovery after surgery, intravenous opioids are typically administered to control the pain, either as intermittent bolus administration by nursing staff or by a patient-controlled analgesia device. Unfortunately, repeated doses or boluses of shorter-acting opioids, such as morphine, oxycodone and fentanyl, result in fluctuating blood concentrations, with the inherent risk of only relatively brief periods of adequate pain relief. Moreover, the use of shorter-acting opioids increases the risk of opioid-associated side effects, such as sedation, nausea and vomiting. An alternative approach to the postoperative use of shorter-acting opioids is therefore called for. In this respect, methadone is an opioid with unique pharmalogical properties that may be advantageous when applied intraoperatively. A single-dose of this long acting opioid could provide a stable analgesia and potentially reduce the need for shorter-acting opioids Method: 110 patients will be included in an investigator-initiated, prospective, randomised, double-blind, controlled trial with two arms: intervention arm (methadone 0.15 mg/kg ideal body weight). Control arm (morphine 0.15 mg/kg ideal body weight). The study will be GCP-monitored, and is approved by the Danish Health and Medicines Authority (2020041652) and the Central Denmark Region Committees on Health Research Ethics (1-10-72-275-19). Hypothesis We hypothesize that a single-dose of intravenous intraoperative methadone is efficient and safe for the treatment of postoperative pain after cystectomy. Objectives The primary objective is to determine whether a single-dose of intravenous methadone reduces postoperative opioid consumption when compared to morphine. The secondary objectives are to compare the effect and safety of intravenous methadone and morphine on postoperative pain, side effects, patient satisfaction and length of stay.