Opioids and opioid receptors in the enteric nervous system: from a problem in opioid analgesia to a possible new prokinetic therapy in humans.
The gut is a neurological organ, which implies that many neuroactive drugs such as opioid analgesics can seriously disturb gastrointestinal function, because many of the transmitters and transmitter receptors present in the brain are also found in the enteric nervous system. One of the most common manifestations of opioid-induced bowel dysfunction is constipation which results from blockade of peristalsis and intestinal fluid secretion. The discovery of opioid receptor antagonists with a peripherally restricted site of action, such as N-methylnaltrexone and alvimopan, makes it possible to normalize bowel function in opiate-treated patients without compromising central opioid analgesia. There is emerging evidence that opioid receptor antagonists may also have prokinetic actions, reversing pathological states of gastrointestinal hypomotility that are due to overactivity of the enteric opioid system.
Holzer
Peter
P
Department of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, A-8010 Graz, Austria. peter.holzer@uni-graz.at
D000701:Analgesics, Opioid / Q000009:adverse effects*; D000818:Animals; D003248:Constipation / Q000139:chemically induced* / Q000188:drug therapy* / Q000503:physiopathology; D017615:Enteric Nervous System / Q000187:drug effects* / Q000503:physiopathology; D005769:Gastrointestinal Motility / Q000187:drug effects / Q000502:physiology; D006801:Humans; D009271:Naltrexone / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D009292:Narcotic Antagonists / Q000494:pharmacology* / Q000627:therapeutic use; D010880:Piperidines / Q000494:pharmacology / Q000627:therapeutic use; D000644:Quaternary Ammonium Compounds; D011957:Receptors, Opioid / Q000378:metabolism
D000701:Analgesics, Opioid; D009292:Narcotic Antagonists; D010880:Piperidines; D000644:Quaternary Ammonium Compounds; D011957:Receptors, Opioid; C032257:methylnaltrexone; D009271:Naltrexone; C419502:alvimopan