Opioids and GI Motility-Friend or Foe? 
The use of opioids for the treatment of chronic non-cancer pain is growing at an alarming rate.  Opioid-induced bowel dysfunction (OBD) is a common adverse effect of long-term opioid treatment manifesting as constipation, nausea, and vomiting.  These effects are primarily mediated by peripheral μ-opioid receptors with resultant altered GI motility and function.  As a result, patients may present with opioid-induced constipation (OIC), opioid-induced nausea and vomiting (OINV), and/or narcotic bowel syndrome (NBS).  This often leads to decreased quality of life and in many cases, discontinuation of opioid therapy.  There is limited evidence to support the use of traditional anti-emetics and laxatives in the treatment of OBD.  Tapering the dose of opioids, switching to transdermal application, opioid rotation, or dual-action opioids, such as tapentadol, may be helpful in the treatment of OBD.  Novel agents, such as peripherally acting μ-opioid receptor antagonists which target the cause of OIC, show promise in the treatment of OBD and should be considered when conventional laxatives fail.  This chapter will review the pathophysiology of OBD, including OINV and OIC, and treatment options available.