Relistor

A drug used to relieve constipation caused by treatment with opioids (pain killers similar to morphine). It is used in patients with pain caused by cancer or treatment for cancer or by other advanced disease. Relistor binds to opioid receptors outside the brain and may block the side effects of opioid drugs without affecting their ability to relieve pain. Relistor is a type of peripheral opioid receptor antagonist. Also called methylnaltrexone bromide.