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.
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.