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ENTEREG® is a peripherally acting µ-opioid receptor antagonist indicated to accelerate the time to upper and lower gastrointestinal (GI) recovery following surgeries that include partial bowel resection with primary anastomosis.


Program Overview

ENTEREG is available only to hospitals that perform surgeries that include a bowel resection and dispensed by pharmacies that are enrolled in the E.A.S.E. ENTEREG REMS Program. This program is designed to ensure that ENTEREG is used in accordance with the FDA-approved label and requires that:

Important Safety Information for ENTEREG

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  • Increased incidence of myocardial infarction was seen in a clinical trial of patients taking alvimopan for long-term use.
  • ENTEREG is available only through a restricted program for short-term use (15 doses) called the ENTEREG Access Support and Education (E.A.S.E.) Program.

ENTEREG Capsules are contraindicated in patients who have taken therapeutic doses of opioids for more than 7 consecutive days immediately prior to taking ENTEREG.

There were more reports of myocardial infarctions in patients treated with alvimopan 0.5 mg twice daily compared with placebo-treated patients in a 12-month study of patients treated with opioids for chronic non-cancer pain (alvimopan, n=538; placebo, n=267). In this study, the majority of myocardial infarctions occurred between 1 and 4 months after initiation of treatment. This imbalance has not been observed in other studies of alvimopan in patients treated with opioids for chronic pain nor in patients treated within the surgical setting, including patients undergoing surgeries that included bowel resection who received alvimopan 12 mg twice daily for up to 7 days (the indicated dose and patient population); (alvimopan 12 mg, n= 1,142; placebo, n= 1,120). A causal relationship with alvimopan with long-term use has not been established.

ENTEREG should be administered with caution to patients receiving more than 3 doses of an opioid within the week prior to surgery. These patients may be more sensitive to Entereg and may experience GI side effects (eg, abdominal pain, nausea and vomiting, diarrhea).

ENTEREG is not recommended for use in patients with severe hepatic impairment, end-stage renal disease, complete gastrointestinal obstruction, or pancreatic or gastric anastomosis, or in patients who have had surgery for correction of complete bowel obstruction.

Overall, the incidence of adverse reactions in short-term surgical clinical trials was similar between patients receiving either ENTEREG or placebo. The most common adverse reaction (incidence ≥1.5%) occurring with a higher frequency than placebo among Entereg treated patients undergoing surgeries that included a bowel resection was dyspepsia (ENTEREG, 1.5%; placebo, 0.8%).

Adverse Event Reporting

Healthcare professionals should report all suspected adverse events associated with the use of ENTEREG.

To report suspected adverse reactions, contact Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc. at 1-877-888-4231
or FDA at 1-800-FDA-1088 (1-800-332-1088) or at