Results of interim analysis indicate lack of efficacy when compared to placebo.

CE-224535 is a new medication being developed as an analgesic and anti-inflammatory agent for the treatment of the signs and symptoms of osteoarthritis (OA). The purpose of this study is to evaluate the analgesic and anti inflammatory efficacy and safety of CE 224,535 versus placebo and naproxen treatment in patients with OA knee pain.

Inclusion Criteria:

• Is a healthy adult 18 to 75 years of age, inclusive, in general good health and with diagnosis of knee OA, as determined by the American College of Rheumatology (ACR) clinical/radiographic classification criteria for OA of the knee.
• Women must be of non childbearing potential (amenorrhea for at least 1 year PLUS have a serum follicle stimulating hormone (FSH) level >30 IU/L, bilateral oophorectomy or hysterectomy), and have a confirmed negative serum pregnancy test at the screening visit prior to randomization.

Exclusion Criteria:

• History of other diseases that may involve the study joint, including inflammatory joint diseases, crystalline disease, endocrinopathies, metabolic diseases, infections, neuropathic disorders, avascular necrosis, Paget's disease, or tumors.
• Women of childbearing potential, or who are pregnant or lactating.