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Methylnaltrexone bromide
Pronunciation
Definition 1
A drug used to relieve certain side effects caused by treatment with opiods (pain killers similar to morphine), such as constipation (hard, dry stools), itching, and low urine flow. 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. (NCI Dictionary)
Definition 2
The bromide salt form of methylnaltrexone, a methyl derivative of noroxymorphone with selective, peripherally-acting mu-opioid receptor antagonistic activity. Methylnaltrexone displaces opioids from peripheral opioid receptors in the gastrointestinal tract, the bladder, and the skin, thereby reversing the opioid-related peripheral side-effects, such as constipation, urinary retention, and pruritis, respectively. Unlike naltrexone and due to the presence of a positively charged nitrogen atom in methylnaltrexone, this agent does not cross the blood-brain barrier and does not affect the centrally-mediated analgesic effect of opioids. (NCI Thesaurus)