Product Overview

Alternative Name: ZK 98.299, ZK 98 299

Description: A study in bonnet monkeys found that low-dose onapristone treatment prevented pregnancy without disturbing the menstrual cycle and ovulation in the majority of cycles. Anovulation and luteal insufficiency occured in some animals during prolonged treatment. Given the resulting inhibition of endometrial receptivity, onapristone was studied as an antiprogestin for endometrial contraception.

Updated date: July 22, 2016

Vertical Tabs


Began discovery in: Prior to 1993

Status Details:
  • Development for contraceptive indication was discontinued in early 2000s. Onapristone is now in Phase II trials for prostate cancer.

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