Crossover Drug-Drug Interaction Study to Determine Effects of Cytochrome P450 3A on Exposure to Mifepristone and Its Metabolites

Inclusion Criteria: * Be healthy * Have a BMI of 18 to 32 kg/m2, inclusive, and body weight more than 50 kg (110 pounds) * Be judged to be in good health, based on the results of medical history, physical examination, vital signs, 12-lead ECG, and clinical laboratory findings * Have suitable veins for multiple venipuncture/cannulation * Female subjects of childbearing potential must use highly effective contraception with low user-dependency. The only acceptable method is an intrauterine device (IUD), provided that the subject has tolerated its use for at least 3 months before the first dose of study drug and undertakes not to have it removed for 1 month after the last dose of study drug. Use of hormonal contraception (by any route, including intrauterine hormone releasing systems) or hormone replacement therapy is NOT acceptable. Exclusion Criteria: * Have multiple drug allergies, or be allergic to any of the components of mifepristone or rifampin * Have a condition that could be aggravated by glucocorticoid blockade (eg, asthma, any chronic inflammatory condition) * Have a history of unexplained vaginal bleeding, endometrial hyperplasia with atypia or endometrial carcinoma * Breastfeeding * In the 1 year before first study drug administration, have a history of drug or alcohol abuse * In the 6 calendar months before first study drug administration, on average * Have smoked more than 5 cigarettes/day * Have consumed more than 21 units of alcohol/week for male subjects or 14 units for female subjects (1 unit/drink = 5 ounces of wine, or 12 ounces of beer, or 1.5 ounces of hard liquor) * In the 2 calendar months before first study drug administration, have donated/lost blood or plasma in excess of 400 mL * In the 30 days before first study drug administration, have participated in another clinical trial of a new chemical entity or a prescription medicine