Application and new advance of opioids

Since the 20th century, opioid-based analgesia has become a global mainstream way of analgesia, but the application of opioid drugs has many disadvantages, such as constipation, respiratory depression, opioid-caused hyperalgesia, opioid-addicted, and so on. Nowadays, to achieve "comfortable medical treatment", to improve the patients' medical experience and the qualities of life, how to improve medication plans of analgesia has became the emphasis. This review mainly describes the development direction of opioid.