%0 Journal Article %A Jim Yu %A Eduardo R. Butelman %A James H. Woods %A Brian T. Chait %A Mary Jeanne Kreek %T Dynorphin A (1–8) Analog, E-2078, Is Stable in Human and Rhesus Monkey Blood %D 1997 %J Journal of Pharmacology and Experimental Therapeutics %P 1147-1151 %V 280 %N 3 %X E-2078 is a dynorphin A (1–8) analog, [N-methyl-Tyr1, N-methyl-Arg7-d-Leu8] Dyn A (1–8) ethylamide. Its biochemical stability against enzymatic degradationin vitro in human and rhesus monkey blood, and in vivo in rhesus monkey blood was studied using matrix-assisted laser desorption/ionization mass spectrometry. In vitrostudies were carried out in freshly drawn human and rhesus monkey blood, incubated at 37°C for various time periods. In vivostudies were conducted by E-2078 i.v. injection to rhesus monkeys, and blood samples were collected at various time points after the injection. It was found that E-2078 was stable against enzymatic degradation in vitro in freshly drawn human and rhesus monkey blood. Minor biotransformation products from E-2078, such as E (1–4), E (1–5) and E (3–6), were detected in vitro in some human and rhesus monkey blood, but they made up less than 5% of the total starting E-2078 peptide. No biotransformation products were detected in the blood samples from in vivo studies. The apparent half-life of elimination of E-2078 in vivo from the rhesus monkey blood was determined to be 44.0 min. The American Society for Pharmacology and Experimental Therapeutics %U https://jpet.aspetjournals.org/content/jpet/280/3/1147.full.pdf