Alvimopan (trade name Entereg) is a drug which behaves as a peripherally acting μ-opioid receptor antagonist. With the limited ability to cross the blood–brain barrier and reach the μ-opioid receptors of the central nervous system, the clinically undesirable effects of centrally acting opioid antagonists (like reversal of opioid-mediated analgesia) are avoided without affecting the intended blockade of μ-opioid receptors in the gastrointestinal tract. It is currently only Food and Drug Administration approved for the treatment of postoperative ileus which it received in May 2008. Medical uses
Alvimopan is indicated in people to avoid postoperative ileus following partial large or small bowel resection with primary anastomosis. Alvimopan accelerates the gastrointestinal recovery period as defined by time to first bowel movement or flatus. Adverse effects
There is a potential risk of myocardial infarction in patients using alvimopan long-term.The most common side effects associated with alvimopan are:

Contraindications
Alvimopan is absolutely contraindicated in patients who have taken therapeutic doses of opioids for more than seven consecutive days immediately prior to when alvimopan would be initiated because individuals with recent exposure to opioids are expected to be more sensitive to the effects of μ-opioid receptor antagonists. The peripheral site of action of alvimopan suggests that such a heightened sensitivity would precipitate gastrointestinal effects beyond dyspepsia. Interactions
Alvimopan is not a substrate for the cytochrome P450 enzyme system. Therefore, no interactions are expected with hepatically metabolized drugs. Alvimopan is substrate for P-glycoprotein. Thus, interactions are to be expected with known P-glycoprotein inhibitors such as amiodarone, bepridil, diltiazem, ciclosporin, itraconazole, quinine, quinidine, spironolactone, and verapamil.
It is available on an inpatient basis at institutions approved by and registered with the Entereg Access Support and Education (E.A.S.E.) program. A person should receive no more than 15 doses. See also
Axelopran
Bevenopran
LY-88329
Methylnaltrexone
Naldemedine
Naloxegol


== References ==