Alvimopan

Alvimopan is a synthetic peripherally restricted p-receptor opioid antagonist. Alvimopan has a greater affinity for the p-receptor than the kappa- or sigma-opioid receptors (K-i = 0.77 nM). The polarity of the molecule limits gastrointestinal absorption and central nervous system penetration. It has limited systemic bioavailability and higher affinity for the p-opioid receptor than naloxone (K-i = 3.7 nM). Completed Phase III trials suggest efficacy in accelerating the recovery of gastrointestinal function after abdominal surgery. Adverse events with all doses have been similar to placebo groups. Further efficacy in alleviating opioid-induced bowel dysfunction in patients with chronic opioid usage has also been demonstrated. This evidence-based review assesses this new drug and discusses its potential role in clinical practice.