A Study of the Safety and Effectiveness of Orally Administered CR845 in Patients With Osteoarthritis of the Hip or Knee

The purpose of this clinical study is to collect information on the effectiveness of CR845 and to look at the safety of different dose levels of CR845 tablets. Oral CR845 has been tested in healthy people. This is the first time that oral CR845 is being tested in patients with osteoarthritis. Four different doses of CR845 will be tested in this study. Participants will be assigned to one of the four treatment groups. The first 6 participants in each of the 4 treatment groups will be given the study drug in an inpatient study unit (clinic) for approximately 2 days. Frequent blood samples will be taken to measure drug levels during these 2 days. Also, because the study drug (CR845) is known to increase urination during the first day, the amount of fluid that participants drink and the amount of urine that they void during the first day will also be measured. At the end of the second day, a member of the clinical staff will check vital signs and the patient's laboratory results prior to discharge from the clinic. After that, the remainder of the treatment period is as an outpatient (at home). This involves taking an additional two tablets twice a day, and maintaining a diary that will be returned to the clinic upon completion.