Randomized, double-blind, placebo controlled parallel group, multi center study in subjects with moderate-severe osteoarthritis.

This will be a randomized, double blind, placebo controlled, parallel group, multi-center study in subjects with moderate-severe OA. Subjects will be randomized to receive flavocoxid 250 mg bid, flavocoxid 500 mg bid, naproxen 500 mg bid or placebo in a 2:2:2:1 ratio. Subjects will take study materials twice daily for twelve (12) weeks. After the 12 week visit subjects in the placebo arm will be re-randomized to the two flavocoxid arms. All subjects will then continue on the study for an additional 12 weeks.

Subjects will keep a diary noting date of onset of symptom change (better or worse), adverse events and cost of all aspects of medical care related directly or indirectly to osteoarthritis.

Laboratory studies for inflammatory markers will be drawn and archived at baseline and at the 12 week visit. In addition, a subgroup of subjects will have arthrocenteses performed at baseline and the 12 week visit and the synovial fluid archived for study of intra-articular inflammatory markers.

Inclusion Criteria:

• OA of the Knee
• K-L Grade 2-3
• Positive response to NSAIDS

Exclusion Criteria:

• K-L grade 1 0r 4 OA of the knee
• History of GI Bleed within past 5 years
• Chronic bleeding disorder