Opiate-induced bowel dysfunction can pose a significant clinical problem. Jonathan Gonenne, MD, and colleagues evaluated the effects of alvimopan, a peripheral mu-opioid antagonist, on codeine-induced delays in gastric, small bowel, and colonic transit time in healthy volunteers (43 women, 31 men). In a double-blinded study, patients were randomized to 1 of 4 groups: alvimopan 12 mg bid with or without codeine sulfate 30 mg 4 times/day, codeine alone, or placebo alone. Gastric emptying and small bowel and colonic transit were measured by scintigraphy.

Primary end points for colonic transit were geometric center (GC) of the colonic counts at 24 hours and time for 50% ascending colon emptying. Codeine delayed gastric, small bowel, proximal, and overall colonic transit (P < .05). Alvimopan reversed the effect of codeine on small bowel and colon (ascending colon and overall colonic transit) and accelerated overall colonic transit, compared with placebo (GC 24 hours, P < .05). Alvimopan did not reverse the codeineinduced delay of gastric emptying (Clinical Gastroenterology and Hepatology, August 2005).