The synergistic effect of µ-opioid receptor agonism and NRI translates clinically into less adverse effects than with pure opioid agonists. This is probably due to less µ-opioid receptor stimulation. Tapentadol is shown in several studies on chronic pain patients to have comparable analgesic effects to traditional opioid pain medications like oxycodone and morphine, but with a more tolerable side-effect profile. In the postoperative setting after dental or orthopedic surgery, studies have shown less nausea and constipation. It has also been suggested a lower frequency of pruritus compared with oxycodone, but no difference in central nervous system symptoms such as somnolence or dizziness. The most dangerous side-effect from opioids is respiratory depression with the potential of fatal outcome. Intravenous oxycodone is shown to have dose dependent effect on respiratory depression decreasing the mean minute volume with a more rapid onset than morphine. One study has attempted to study respiratory depression after tapentadol administration, but failed due to technical failure of the pulse oximetry device. The investigators have not found any other publications from short-term postoperative pain management comparing any respiratory effect of tapentadol to the traditional opioids.