This is a 28-day, single-center, double-blind, placebo-controlled inpatient study of the administration of risperidone alone or in combination with mifepristone in healthy adult male volunteers to determine the average change in absolute weight at Day 28 compared to baseline.

This is a 28-day, single-center, double-blind, placebo-controlled inpatient study of the administration of risperidone alone or in combination with mifepristone in healthy adult male volunteers. The primary study objective is to determine the mean change in absolute weight at Day 28 compared to baseline in normal healthy male volunteers treated with risperidone plus mifepristone or risperidone alone. The secondary study objectives are to determine the mean percent change in baseline body weight; and the proportion of subjects that gain less than 5% and less than 7% of their baseline body in the treatment groups.

Inclusion Criteria:

• BMI ≥ 18 and ≤ 23 kg/m2
• Able to provide written informed consent
• Routine clinical laboratory tests either within normal limits or not clinically meaningful if outside of normal limits
• AST, ALT, Tbili within normal limits at screening
• Medical and psychiatric history and physical examination devoid of any significant findings that would interfere with participation or interpretation of results in this study
• Agree to use a barrier method of birth control for 28 days following the last dose of study medication
• Have maintained a stable weight for at least 6 months prior to Screening

Exclusion Criteria:

• 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 drug of abuse (including amphetamines, cannabinoids, barbiturates, cocaine, opiates, benzodiazepines) unless prescribed by a physician
• 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 risperidone
• Any other clinically significant abnormality on screening laboratory tests
• QTc Bazzett's ≥ 450 msec
• History of or current 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
• Any history of a movement disorder such as Tardive Dyskinesia, Parkinsonism
• Any personal or family history of Neuroleptic Malignant Syndrome