“…All opioids act similarly in this respect, and although side effects usually occur at higher doses than analgesic effects, they still remain a major clinical problem which render many patients helpless, unable to get out of bed, with the subsequent risk of more severe complications such as hypoxia, pneumonia, deep venous thrombosis, pulmonary embolism, ileus and decubitus. The apparent discord between the obvious need for opioids and the abhorred side effects have led clinicians to try various methods of alleviating opioid-related side effects: 1) the combination of intravenous morphine with a μ-receptor antagonist such as naloxone by patient-controlled analgesia (PCA) has been largely disappointing (Sartain, 2003;Zhao, 2005); 2) a similar combination using a μ-receptor antagonist, alvimopan, with limited oral bioavailibility (thus only acting in the GI tract) has fared better and has been shown to improve tolerance to solid foods, time to first bowel movement and passage of stool, although the magnitude of improvements were moderate (Herzog, 2006;Tan, 2007); 3) the use of simple osmotic laxatives have been shown to reduce time to first defecation from 69 to 45 hours with subsequent early hospital discharge (Hansen, 2007); 4) early postoperative oral intake seems to be superior to delayed intake by reducing time to first solid diet, presence of bowel sounds, and shorter hospital stay, at the expense of slightly increased nausea (Charoenkwan, 2007); 5) the combination of intravenous morphine with butorphanol reduces opioid requirements and some opioid-related side effects, but causes sedation, sweating and dry mouth ; 6) the combination with nalbuphine, a mixed opioid agonist-antagonist, also seems to attenuate opioid-related nausea, but other opioid-related side effects remain unchanged ; 7) the omission of a background rate of infusion of morphine for intravenous patient-controlled analgesia (PCA) seems to reduce overall morphine consumption, reduce nausea, vomiting and dizziness but, again, other opioid-related side effects remain unchanged (Chen, 2011); 8) intravenous oxycodone seems to cause less opioid-related sedation than intravenous morphine, but other side effects are similar, suggesting a difference caused by stochastic variation (Lenz, 2009). …”