The study treatment period is 15 days in length and includes patients with pituitary Cushing's disease who are candidates for surgical intervention as well as and patients who have recurrent Cushing's post operatively.

Inclusion Criteria:

• Patients with pituitary Cushing's disease within the two months prior to study entry
• Patients for whom written informed consent to participate in the study has been obtained
• Female patients of child bearing potential who have not undergone clinically documented total hysterectomy and/or ovariectomy, or tubal ligation must agree to use barrier contraception throughout the course of the study, and for one month after the study has ended

Exclusion Criteria:

• Female patients who are pregnant or lactating
• Patients who have been previously treated with certain medications may be required to be without certain medications prior to entering the study
• Poorly controlled diabetes mellitus as indicated by the presence of ketoacidosis or HgbA1C > 10
• Patients who have congestive heart failure, unstable angina, cardiac arrhythmia or history of acute MI less than one year prior to the study entry or clinically significant impairment in cardiovascular function (e.g. blood pressure of 190/100mmHg or greater)
• Patients with chronic liver disease
• Patients with clotting disorders or abnormal blood counts
• History of immuno-compromise, including a positive HIV test result
• Patients with active gall bladder disease
• Patients who have participated in any clinical investigation with an investigational drug within 1 month prior to dosing
• Patients with active malignant disease (with the exception of basal cell carcinoma or carcinoma in situ of the cervix)