This is a two-week study testing the efficacy and safety of mifepristone in the prevention of olanzapine-induced weight gain in healthy male volunteers by measuring changes in body weight and BMI.

Inclusion Criteria:

• Healthy male volunteers between 18 and 40 years of age
• BMI between ≥ 18 and ≤ 25
• Able to provide written informed consent
• Routine clinical laboratory tests either within normal limits or not clinically meaningful if outside of normal limits

Exclusion Criteria:

• History of Cushing's syndrome or Addison's disease
• Prior or current history of any psychiatric disorder, including eating disorders such as anorexia nervosa, bulimia nervosa, or binge-eating disorder
• Positive urine drug screen for any non-prescribed drug of abuse (including but not limited to amphetamines, cannabinoids, barbiturates, cocaine, opiates, benzodiazepines)
• Participation in a clinical investigation of any drug, biological or other investigational therapy within 30 days prior to dosing
• Have a history of an allergic reaction to either mifepristone or olanzapine
• Any clinically significant abnormality on screening laboratory tests
• QTc Bazzett's ≥ 450 msec
• Any major medical condition, which in the opinion of the Investigator would place the patient at undue risk.
• Receiving any prescription or over-the-counter medications that could potentially affect appetite or weight
• History of recent (within 6 months of screening) significant weight fluctuation