Antiglucocorticoid Mifepristone

ZK 98734 (lilopristone) is a potent experimental progesterone inhibitor and abortifacient in doses of 25 mg twice daily. Like mifepristone, it also appears to have antiglucocorticoid activity. 

An adolescent girl with Cushingoid features and osteoporosis took mifepristone 400 mg/day for its antiglucocorticoid effect in an attempt to prevent further bone loss (16). Her striae, weight gain, and buffalo hump markedly improved, and further bone loss was halted. However, with each of the two 6-month courses of mifepristone (9 months apart) she developed massive simple endometrial hyperplasia and a markedly enlarged uterus. This reverted to normal after withdrawal of mifepristone. 

Information is only available for mifepristone since there is very limited clinical experience with other PAs and SPRMs. Owing to its specific action at the PR and GR, serious untoward effects are rare and mifepristone is well tolerated. Antiglucocorticoid effects are usually only seen with doses exceeding 200 mg daily [59]. Chronic administration of mifepristone has been associated with the development of biochemical hypothyroidism which requires observation and follow-up [115]. 

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