The FDA has approved naloxegol (Movantik – AstraZeneca), a pegylated derivative of the opioid antagonist naloxone, for oral treatment of opioid-induced constipation in adults with chronic noncancer pain. It is the only oral opioid antagonist approved for this indication in the US.

The FDA has approved the marketing of alvimopan (Entereg - Adolor/GlaxoSmithKline), a selective muopioid receptor antagonist, for oral treatment of postoperative ileus after bowel resection. The only other drug in this class available in the US is subcutaneously injected methylnaltrexone (Relistor), which is approved for treatment of opioid-induced constipation in patients with advanced illness receiving palliative care.

The FDA has approved subcutaneous injection of methylnaltrexone (Relistor - Wyeth/Progenics), a selective mu-opioid receptor antagonist, for treatment of opioid-induced constipation in patients with advanced illness (such as incurable cancer or end-stage chronic obstructive pulmonary disease) who are receiving palliative care.