methylnaltrexone bromide
(MEH-thul-nal-TREK-sone BROH-mide)
A drug used to relieve constipation caused by the use of opioids (pain killers that are like morphine). It is used in adults with pain caused by cancer or treatment for cancer or by other advanced disease. Methylnaltrexone bromide binds to opioid receptors outside the brain and may block the side effects of opioid drugs without affecting their ability to relieve pain. Methylnaltrexone bromide is a type of peripheral opioid receptor antagonist. Also called Relistor.