- For the mifepristone studies only: Patients taking medications that alter CYP3A4 activity will not be eligible for the mifepristone study, since this P450 system metabolizes mifepristone. Patients with hypokalemia (K < 3.5 mEq/L), despite medical therapy with replacement or mineralocorticoid antagonists will also be excluded from the mifepristone studies. Such patients may participate in other components of the protocol. Medications affecting CYP3A4 may be adjusted to allow participation in the mifepristone component, with a one week washout period.