FDA Approves Relistor for Opioid-Induced Constipation

The U.S. Food and Drug Administration today approved Relistor (methylnaltrexone bromide) to help restore bowel function in patients with late-stage, advanced illness who are receiving opioids on a continuous basis to help alleviate their pain.

Opioids are often prescribed on a continuous basis for patients with late-stage, advanced illness to help alleviate pain. This includes patients with a diagnosis of incurable cancer, end-stage Chronic Obstructive Pulmonary Disease (COPD) from emphysema, heart failure, Alzheimer’s disease with dementia, HIV/AIDS or other advanced illnesses.

Opioids can interfere with normal bowel elimination function by relaxing the intestinal smooth muscles and preventing them from contracting and pushing out waste products. Relistor acts by blocking opioid entrance into the cells thus allowing the bowels to continue to function normally.

“This new drug will be helpful to patients who experience severe constipation associated with the continuous use of morphine or other opioids, which are an important part of care for patients with late-stage, advanced illness.” said Joyce Korvick, M.D., deputy director of the Division of Gastroenterology Products, FDA.

Relistor is an injectable medication. It can be administered as needed, but not to exceed one dose in a 24 hour period. The recommended starting schedule is one dose every other day as needed for patients with late-stage advanced illness. Relistor is not recommended for patients with known or suspected intestinal obstructions.

Common side effects include abdominal pain, gas, nausea, dizziness and diarrhea. If severe diarrhea, vomiting, nausea or abdominal pain occurs while taking Relistor, patients should discontinue use of the medication in consultation with their health care professional.

The safety and effectiveness of the drug was demonstrated in clinical studies conducted by the sponsors. The two randomized, double-blind placebo-controlled studies involving a total of 287 participants were conducted over a four month period. The median age of the study participants was 68 years, and 51 percent of the participants were women. In both studies, all patients had advanced late-stage illnesses with a life expectancy of less than 6 months. Prior to treatment with Relistor, participants had either less than three bowel movements in the week prior to treatment or no bowel movement for more than 2 days. Patients who were treated with Relistor had a significantly higher rate of elimination than those receiving placebo. The safety and effectiveness of Relistor have not been studied in pediatric populations.

Relistor is manufactured by Wyeth Pharmaceuticals Inc., Philadelphia, PA., and Progenics Pharmaceuticals, Tarrytown, NY.