Alvimopan (Entereg), a Peripherally Acting mu-Opioid Receptor Antagonist For Postoperative Ileus.

574 P&T® • October 2008 • Vol. 33 No. 10 INTRODUCTION In 2007, Goldstein et al. sought to determine the economic burden attributed to the management of postoperative ileus (POI) associated with abdominal surgery in the U.S. Their study revealed an annual national hospital cost of $1.46 billion for both the index hospitalization and any readmissions within 30 days. POI is one of the expected complications of major abdominal surgery. It can occur with other procedures, including extra peritoneal, gynecological, joint replacement, and cardiovascular surgeries, and it is the most common cause of delayed hospital discharge after abdominal surgery. POI is the impairment of gastrointestinal (GI) motility after intra-abdominal surgery or other non-abdominal pro cedures. It affects all segments of the GI tract and may last from five to six days or even longer, and it has the potential to delay GI recovery and hospital discharge until its resolution. POI is characterized by abdominal distention and bloating, nausea, vomiting, pain, accumulation of gas and fluids in the bowel, and delayed passage of flatus and defecation (Table 1). It is the result of a multifactorial process that includes inhibitory sympathetic input and the release of hormones, neurotransmitters, and other mediators (e.g., endogenous opioids). A component of POI also results from an inflammatory reaction and the effects of opioid analgesics. Morphine and other mu-opioid receptor agonists are universally used for the treatment of acute postsurgical pain; however, they have an inhibitory effect on GI tract motility and may prolong the duration of POI. These changes result in decreased motility and inhibition of propulsive motion. Because opioid receptors are present in the GI tract, when opioids bind to these receptors, they can disrupt normal GI function, which allows for the passage of food through the GI tract. Con sequently, POI can cause significant discomfort and pain. POI is associated with longer hospital stays and a high utilization of health care resources. The duration of POI varies among patients and is associated with delayed enteral feeding, resulting in a negative impact on postoperative pain management and an increased risk of other postoperative morbidities. Despite the consequences of the possible causative factors, the ensuing clinical injury associated with POI is characterized by abdominal distention and a delay in the return to normal bowel function.