New Pharmacological Drug Classes Introduced in 2008
During pre-marketing clinical trials, the most common adverse reactions among bowel resection patients receiving alvimopan were anemia, dyspepsia, hypokalemia, back pain, and urinary retention. Vigorous gastrointestinal side effects (including abdominal pain, nausea, vomiting, and diarrhea) can be expected when opioid-tolerant patients are given alvimopan, so patients who have taken opioids for the 7 consecutive days immediately prior to surgery should not be considered candidates for the drug.
The oral bioavailability of alvimopan is low (~6%).
An active metabolite is formed in the gut by intestinal microflora. Since both the parent and metabolite are p-glycoprotein substrates, clinically significant drug interactions may surface with strong p-glycoprotein inhibitors (e.g., verapamil, cyclosporine, amiodorone, itraconazole, quinine, spironolactone, quinidine, diltiazem, and bepridil).
Biliary secretion is the primary pathway of elimination for unabsorbed alvimopan and the metabolite formed in the gut is eliminated in the feces and urine as unchanged metabolite, the glucuronide conjugate, and other minor metabolites.
The half-life of alvimopan and the gut metabolite ranges from 10 to 18 hours. The drug accumulates approximately 10-fold in patients with severe hepatic impairment, thereby precluding administration to this group.
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