Alvimopan (Entereg)

A peripherally acting μ-opioid antagonist.

Limited ability to cross the blood–brain barrier, and avoids many undesirable side-effects of the opioid agonists such as constipation, without affecting analgesia or precipitating withdrawal symptoms.

Indicated to avoid postoperative ileus following partial large or small bowel resection with primary anastomosis.

Accelerates the gastrointestinal recovery period to first bowel movement or flatus.

Competitively binds to mu-opioid receptor in the gastrointestinal tract.

Peak plasma concentration is reached approximately 2 hours after oral dosing.

C max for metabolite occurs 36 hours after an oral dose

Has a high affinity for the peripheral mu-receptor results in an absolute bioavailability less than 7%.

80% to 90% of systemically available drug is bound to plasma protein.

Undergoes no significant hepatic metabolism, but is metabolized by intestinal flora to an active metabolite with no clinically significant contribution to drug effect.

Undergoes 35% renal excretion and greater than 50% biliary excretion.

Drug metabolized by intestinal flora is excreted in the feces.

Half-life of elimination is 10 to 17 hours, while that of the gut metabolite is 10 to 18 hours.

Approved for short term use of no more than 15 doses.

Available on an inpatient basis at institutions approved by and registered with the Entereg Access Support and Education (E.A.S.E.) program.

The drug is a 12 mg blue hard gelatin capsule to be administered 12 mg 30 minutes to 5 hours preoperatively and 12 mg twice daily for seven days postoperatively.

A patient should receive no more than 15 doses. Adverse effects[edit]

The most common side effects associated with alvimopan are: dyspepsia, hypokalemia, back pain and delayed urination.

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 expect to be more sensitive to the effects of mu-opioid receptor antagonists.

The peripheral site of action of alvimopan suggests a heightened sensitivity would precipitate gastrointestinal effects beyond dyspepsia.

A 12 month study of alvimopan dosed at 0.5 mg twice daily reported observed more myocardial infarction in the treatment group compared to placebo, but this effect has not been reproduced in subsequent studies.

Use is not recommended in surgical candidates for correction of a complete bowel obstruction.

A substrate for p-glycoprotein and interactions with known p-glycoprotein inhibitors such as amiodarone, depridil, diltiazem, cyclosporine, itraconazole, quinine, quinidine, spironolactone, and verapamil may occur.

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