[News from the cochrane library: mu opioid antagonists for opioid-induced bowel dysfunction]

Constipation and other gastrointestinal symptoms are frequent adverse effects of either short-term postoperative or chronic opioid therapy. The review authors have identified 23 studies to evaluate the efficacy of micro-opioid antagonists for the prevention and treatment of these complications. The data on safety and efficacy of the traditional antagonists naloxone and nalbuphine are insufficient. The results of studies with the newer, peripherally-acting antagonists alvimopan and methylnaltrexone are promising. Methylnaltrexone resulted in four studies with healthy probands in a significant shortening of the gastrointestinal transit time (-52 min). In the postoperative setting, five studies showed a significant improvement of the hazard ratios for different outcomes (e. g., bowel movement, tolerance of solid food) in the alvimopan group. Future studies will be needed to show whether these results can be reproduced in different patient groups on a larger scale. Also, with regard to other pharmacological (e. g., lactulose) and non-pharmacological interventions, the role of the above-mentioned not yet approved medications needs to be defined.