Entereg (alvimopan), a mu-opioid receptor antagonist designed to treat opioid-induced constipation, has recently been approved by the FDA to help restore bowel function following partial bowel resection. Common side effects include hypocalcemia, anemia, constipation, dyspepsia, and flatulence. One study revealed a higher incidence of myocardial infarctions than placebo, but the relationship was not present in other studies.

Source: FDA Press Release