The irreversible narcotic antagonistic and reversible agonistic properties of the fumaramate methyl ester derivative of naltrexone.
The fumaramate methyl ester derivatives of naltrexone (beta-FNA) and oxymorphone (beta-FOA) were both found to be reversible agonists on the guinea pig ileal longitudinal muscle preparation. In addition, beta-FNA possessed on irreversible antagonistic effect against morphine whereas beta-FOA had no such capacity. Analysis by pA2 values revealed that beta-FOA resembled pure agonists like morphine and enkephalin while beta-FNA resembled the mixed agonist-antagonists like nalorphine and pentazocine. The antagonism by beta-FNA was very selective in that it antagonized pure agonists but had little or no effect on the effects of either mixed agonist-antagonists, ethylketocyclazocine or other non-opiate-type agonists like norepinephrine.
D000345:Affinity Labels; D000818:Animals; D007082:Ileum; D008297:Male; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D009270:Naloxone / Q000031:analogs & derivatives*; D009271:Naltrexone / Q000031:analogs & derivatives* / Q000494:pharmacology; D010111:Oxymorphone / Q000031:analogs & derivatives / Q000494:pharmacology; D011957:Receptors, Opioid / Q000187:drug effects* / Q000378:metabolism; D013329:Structure-Activity Relationship
D000345:Affinity Labels; D011957:Receptors, Opioid; D009270:Naloxone; D009271:Naltrexone; C024524:beta-funaltrexamine; C024525:oxymorphone fumarate methyl ester; D010111:Oxymorphone