Opiate-induced bowel dysfunctioncan pose a significant clinical problem.Jonathan Gonenne, MD, and colleaguesevaluated the effects of alvimopan,a peripheral mu-opioid antagonist,on codeine-induced delays ingastric, small bowel, and colonic transittime in healthy volunteers (43women, 31 men). In a double-blindedstudy, patients were randomized to 1of 4 groups: alvimopan 12 mg bid withor without codeine sulfate 30 mg 4times/day, codeine alone, or placeboalone. Gastric emptying and smallbowel and colonic transit were measuredby scintigraphy.
Primary end points for colonic transitwere geometric center (GC) of thecolonic counts at 24 hours and timefor 50% ascending colon emptying.Codeine delayed gastric, small bowel,proximal, and overall colonic transit(P < .05). Alvimopan reversed theeffect of codeine on small bowel andcolon (ascending colon and overallcolonic transit) and accelerated overallcolonic transit, compared withplacebo (GC 24 hours, P < .05). Alvimopandid not reverse the codeineinduceddelay of gastric emptying(Clinical Gastroenterology and Hepatology,August 2005).