[Understanding Opioid-induced Adverse Effects and its Managements].

Opioids are potent analgesics and improve both noci- ceptive and neuropathic pain. However, some patients suffer opioid-induced adverse effects, including not only somnolence, nausea and vomiting, and constipation (bowel dysfunction) but also osteoporosis, immunode- ficiency, paradoxical hyperalgesia and addiction. These adverse effects could derive from stimulating opioid receptors either in the central nervous system or at the periphery. Here, we explain the mechanisms of opioid-induced adverse effects and respective manage- ments of them. To control opioid-induced constipation, the peripheral-acting mu-opioid receptor antagonists (PAMORAs) have been widely used in USA. We dis- cuss features of and expectations for PAMORAs in Japan. Further, to avoid developing opioid addiction, we introduce the concept of 'Health literacy' and the measuring tool 'Newest Vital Sign Japanese version'. Controlling pain by opioids adequately and preventing and managing opioid-induced adverse effects ade- quately can result in improvement of QOL of patients with chronic pain.