Inclusion Criteria:  The patient is scheduled for elective unilateral total knee arthroplasty or hip arthroplasty under general anesthesia Fluent skills in finnish language (to understand the given information and to be able to give informed consent and communicate with the study personnel) Age between 35 and 80 years Weight between 50 and 100 kg ASA (American Society of Anesthesiologists) status 1-3 Written informed consent from the patient  Exclusion Criteria:  A previous history of intolerance to the study drug or related compounds and additives Disease or condition affecting patient's ability to give written informed consent Existing or recent significant disease possible affecting absorption, distribution, metabolism, excretion or response to the study drug History of cardiac disease (valvular insufficiency, severe left ventricular dysfunction) or abnormal ECG rhythm (bradycardia < 50/min, 2nd or 3rd degree atrio-ventricular block, pacemaker) Chronic opioid use or use of other analgesic adjuvants such as pregabalin, gabapentin, amitriptyline or duloxetine Participation in any other study concomitantly or within one month prior to the entry into this study Clinically significant abnormal findings in physical examination or laboratory screening Use of drugs or natural products known to cause enzyme induction or inhibition Pregnancy or breastfeeding Spinal anesthesia Preoperative systolic blood pressure <110 mmHg