ADL-8-2698 is a novel peripherally restricted opioid antagonist that may selectively prevent opioid-induced gastrointestinal effects without reversing analgesia. Alvimopan reduces certain side effects of narcotic medications that are often used to prevent pain caused by surgery.Narcotic medications can cause stomach pain, bloating, nausea, vomiting, and constipation. These side effects can delay recovery in patients undergoing gastrointestinal surgery. Alvimopan works by preventing these side effects without reducing the pain-relieving effects of the narcotic. Alvimopan is used to speed recovery of stomach and intestinal functions after a gastrointestinal surgery and to prevent side effects caused by narcotic medications. Alvimopan may also be used for other purposes not listed in this medication guide.