This is of interest since NSAIDs are frequently administered as premedication before surgery. There are several disadvantages associated with the use of COX-2 inhibitors, e.g. the risk of myocardial infarction after long-term use (> 1 year), and potentially reduced bone healing after orthopedic surgery. However, this has not been shown with short-term use (days/week). The disadvantages associated with the use of e.g. ketorolac (a COX-1 inhibitor) are i.a. increased bleeding tendency, which is unfavourable for the surgeon, and increased risk of gastric ulcer. Therefore, it is of interest to investigate other ways of preventing opioid-induced hyperalgesia. In a recent animal study it has been shown that gradual dose reduction of remifentanil (vs. abrupt withdrawal of a relatively high remifentanil dose) can prevent the development of hyperalgesia after end of infusion. In this study we will i.a. investigate whether this is also the case in humans. In this new model, the study participants will get remifentanil infusion with two different dose reduction regimes: gradual reduction or abrupt withdrawal.