This study is an investigator-initiated, prospective, randomised controlled trial with two arms: an intervention arm (methadone) and a control arm (fentanyl). Patients scheduled for tonsillectomy at Randers Regional Hospital, Denmark, will be approached for study participation.~Patients are randomised in a 1:1 ratio in blocks of varying sizes (between 4 and 8) to receive either intraoperative methadone or fentanyl. The randomisation assignment will be handled by the hospital pharmacy using a web-based central randomisation procedure (www.sealedenvelope.com).~The study drug will be prepared by the hospital pharmacy at Aarhus University Hospital and delivered as kits with identical appearance, marked with the randomization number (1-130). On the day of surgery, a kit will be opened and a 10 ml syringe with study drug (methadone 2 mg/ml or fentanyl 30 microgram/ml or ) will prepared by a health care professional (nurse or medical doctor not involved in the study or the treatment of patients). Once prepared, the blinded study drug will be given to and handled by one of the research team members and administered after induction of anesthesia and prior to surgery~The dose of the study drug will be administered as intravenous bolus dose in equipotent doses (0.2 mg/kg / 3 μg/kg) corresponding to 1 ml for every 10 kg of ideal body weight (women: height (cm) - 105. Men: height (cm) - 100)) after induction of anaesthesia and before the start of surgery.~Postoperative data will be obtained by reviewing hospital records, by interview and electronic questionnaires sent by email.
A randomized controlled trial evaluating the efficacy and safety of single-shot intraoperative methadone for postoperative pain in patients undergoing tonsillectomy. Fentanyl is used as an active comparator