TY - JOUR T1 - Orientation of the oxygen atom at C-6 as a determinant of agonistic activity in the oxymorphone series. JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 496 LP - 500 VL - 200 IS - 3 AU - A Z Ronai AU - F F Foldes AU - E F Hahn AU - J Fishman Y1 - 1977/03/01 UR - http://jpet.aspetjournals.org/content/200/3/496.abstract N2 - The kinetics of various oxymorphones, their 6-methylene analogs and the 6-hydroxy-epimers corresponding to naloxone and naltrexone have been studied in the longitudinal muscle strip of the guinea-pig ileum. Substitution of the oxygen at C-6 by amethylene group slightly increased antagonistic activity of the resulting structures, without significantly influencing agonistic activity relative to the parent compound. The alpha-orientation of the hydroxy group at C-6 enhanced the agonistic property of both naloxone and naltrexone. The beta-compounds, however, were pure antagonists, with potencies similar to those of the parent keto structures. ER -