March 8, 2009

Relistor® Improves Opioid-induced Constipation


Relistor® Improves Opioid-induced Constipation

The newly approved agent Relistor® (methylnaltrexone) provides relief for patients with constipation caused by use of opioids. These results were recently published in the New England Journal of Medicine.

Opioids are some of the most potent pain relievers currently available. They are often used by patients with terminal cancers. One of the common side effects of opioids is constipation, which may become quite severe. Although diet, movement, fluid intake, enemas, laxatives, and some approved agents may help relieve opioid-induced constipation, more-effective relief is still needed.

Relistor is a µ-opioid–receptorantagonist. It was recently approved for the treatment of opioid-induced constipation. Researchers from medical institutions and hospices in the United States recently conducted a clinical study to evaluate the effectiveness and safety of Relistor among patients with opioid-induced constipation. This study included 133 patients who had received opioids for two weeks or more. Patients had also been treated with laxatives for at least three days, which provided no relief. In the study one group of patients was treated with Relistor in an attempt to relieve their constipation, while the other group received a placebo (inactive substitute).

  • Nearly half of the patients treated with Relistor had laxation (defecation) within four hours after the first dose compared with 15% of patients who received placebo.
  • Abdominal pain and flatulence were the most common side effects associated with Relistor.
  • No pain changes were noted with the use of Relistor.
  • The results obtained from Relistor were consistent for at least three months.

The researchers concluded: “[Relistor] rapidly induced laxation in patients with advanced illness and opioid-induced constipation.” Patients with constipation induced by opioids that is not relieved through laxatives may wish to speak with their physician regarding their individual risks and benefits of treatment with Relistor.

Reference: Thomas J, Karver S, Austin G, et al. Methylnaltrexone for opioid-induced constipation in advanced illness. New England Journal of Medicine. 2008;358:2332-2343.

Related News: Relistor™ Approved for Opioid-induced Constipation (4/30/2008)

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