It has been surprisingly discovered that administration of the same dose of mifepristone can produce widely varying blood serum levels in different patients. The varied blood serum levels can result in some patients not receiving an efficacious dose of mifepristone. For the same dose of mifepristone, the blood serum levels can differ by as much as 800% from one patient to another. Thus, a method for ensuring that the blood serum levels of mifepristone remain in an efficacious and safe range is needed.