Effectiveness of two opioid antagonists in treating opioid-induced constipation

This literature review reports the effectiveness of two peripheral opioid antagonists to relieve constipation caused by prolonged use of opioids, primarily in patients with advanced cancer.

Opioid-induced constipation can cause great discomfort to patients who use opioids for prolonged periods and on occasion decline pain-relief in an effort to help aid laxation. The use of peripheral opioid antagonists can help reverse the slowing of the gut caused by the opioids, but the correct one must be used in order not to reverse the important analgesic effects the opioids provide.

Information was obtained by searching the databases British Nursing Index, CINAHL and Medline.

Selection criteria were as follows: original research in the form of randomized controlled trials; articles had to be written in English; articles had to focus on the effectiveness of naloxone and methylnaltrexone in the treatment of opioid-induced constipation; the search was limited to the period 1990-2008.

Nineteen articles were included in the study. The results from the studies indicate that due to fewer withdrawal effects and less reversal of analgesia experienced, methylnaltrexone is more effective at relieving opioid-induced constipation.

The recent development of methylnaltrexone into a commercially-viable drug indicates its effectiveness. It may help patients suffering from the intense discomfort that constipation can cause.