Opioid-induced bowel dysfunction: pathophysiology and potential new therapies.

摘要: Opioid treatment for postoperative or chronic pain is frequently associated with adverse effects, the most common being dose-limiting and debilitating bowel dysfunction. Postoperative ileus, although attributable to surgical procedures, often exacerbated by opioid use during following surgery. ileus marked increased inhibitory neural input, heightened inflammatory responses, decreased propulsive movements fluid absorption in gastrointestinal tract. The of opioids characterised a constellation symptoms including hard dry stools, straining, incomplete evacuation, bloating, abdominal distension gastroesophageal reflux. current management opioid-induced dysfunction among patients receiving analgesics consists primarily nonspecific ameliorative measures. Intensive investigations into mode action have three receptor classes -mu, delta kappa- that mediate myriad peripheral central actions opioids. Activation mu-opioid receptors tract responsible inhibition gut motility, whereas nervous system analgesic Blocking therefore logical therapeutic target managing Available antagonists such as naloxone are limited because they readily absorbed, cross blood-brain barrier, act at reverse analgesia elicit withdrawal. Methylnaltrexone alvimopan recently developed activity restricted receptors. Both shown ability without reversing precipitating withdrawal signs non-surgical pain. In addition, recent clinical studies suggest it may normalise function blocking laparotomy opioid-related ileus.