Chj. Verhoeven et al., IN-VITRO AND IN-VIVO METABOLISM OF THE PROGESTAGEN ORG-30659 IN SEVERAL SPECIES, Drug metabolism and disposition, 26(11), 1998, pp. 1102-1112
The metabolism of Org 30659 [(17 -11-methylene-19-norpregna-4,15-dien-
20-yn-3-one], a new potent progestagen currently under clinical develo
pment by NV Organon for use in oral contraceptive and hormone replacem
ent therapy, was studied in vivo after oral administration to rats and
monkeys and in vitro using rat, rabbit, monkey, and human liver micro
somes and rat and human hepatocytes. After oral administration of [7-H
-3]Org 30659 to rats and monkeys, Org 30659 was extensively metabolize
d in both species. Fecal excretion appeared to be the main route of el
imination. In rats, opening of the A-ring, resulting in a 2-OH,4-carbo
xylic acid, 5 alpha-H metabolite of Org 30659, was the major metabolic
route in vivo. Other metabolic routes involved the introduction of an
OH group at C15 beta, followed by a shift of the Delta(15)-double bon
d to a 16/17-double bond with subsequent removal of the OH group at C1
7 and reduction of the 3-keto,Delta(4) moiety followed by sulfate conj
ugation of the 3-OH substituent. These metabolic routes observed in vi
vo were also major routes in incubations with rat hepatocytes. In rat
liver microsomes, Org 30659 was metabolized by reduction of the 3-keto
,Delta(4) moiety. Rat hepatocyte incubations with Org 30659 were more
representative of the in vivo metabolism of Org 30659, compared with r
at microsomal incubations. Both in vitro and in vivo, the majority of
the metabolites were 3 alpha-OH,4,5 alpha-dihydro derivatives. In monk
eys, Org 30659 was mainly metabolized at the C3- and C17-positions in
vivo. The 3-keto moiety was reduced to both 3 beta-OH and 3 alpha-OH s
ubstituents. In addition to phase I metabolites, glucuronic acid conju
gates were observed in vivo. In monkey liver microsomes, the 6 beta-OH
metabolite of Org 30659 was the major metabolite present. Similar to
the monkey liver microsomes, rabbit and human liver microsomes convert
ed Org 30659 to the 6 beta-OH metabolite. This metabolite was also the
major metabolite in incubations with human hepatocytes.