Onapristone
CHEMICAL COMPOUND
ZK-89299; ZK89299; ZK 89299; ZK 89,299; ZK-89,299; ZK-299; ZK 299; ZK299
Onapristone () (developmental code names ZK-89299, ZK-299) is a synthetic and steroidal antiprogestogen with additional antiglucocorticoid activity which was developed by Schering in and described in 1984 but was never marketed. in in It is a silent antagonist of the progesterone receptor (PR), in contrast to the related antiprogestogen mifepristone (which is a weak partial agonist of the receptor).