To study the efficacy and safety of Naproxcinod vs. Placebo and Naproxen in the treatment of signs and symptoms of Osteoarthritis.

This is a 13 week randomized, double-blind, parallel group, multicenter study comparing efficacy and safety of Naproxcinod, Placebo and Naproxen.

Inclusion Criteria:

• Men and women (40 or older) with a diagnosis of primary OA of the hip
• Must be a current chronic user of NSAIDS or acetaminophen
• Must discontinue all analgesic therapy at Screening

Exclusion Criteria:

• Uncontrolled Hypertension or Diabetes
• Hepatic or renal impairment
• Current or expected use of anticoagulant
• Clinically relevant abnormal ECG
• A history of alcohol or drug abuse
• Diagnosis of gastric or duodenal ulceration and/or history of significant gastro-duodenal bleeding, within the last 6 months
• Current medical disease, including arthritic, that could confound or interfere with the evaluation of efficacy
• Candidates for imminent joint replacement
• Participation within 30 days prior to screening in another investigational study