• 6-week Efficacy Study The objective of this study is to prove the safety and non-inferiority of analgesic efficacy of CG100649 2 mg vs. celecoxib 200 mg, and analgesic superiority of CG100649 2 mg vs. placebo, when administered once a day in patients with osteoarthritis of the hip or knee over the 6 week Treatment period. The primary efficacy parameter is the difference from Baseline to Week 6 in the Western Ontario and McMaster Universities Index of Osteoarthritis (WOMAC)-Pain subscale.
• Extended Safety Study The objective of the Extended Safety Study is to collect a total of 24 weeks of safety data for CG100649 including the initial 6 weeks of safety data, and an additional 18 weeks of safety data for those subjects who agree on the consent form to continue into the Extended Safety Study. Subjects will be administered CG100649 2 mg only during 18 weeks of Extended Safety Study.

1. Number of Subjects: 350 (2:2:1 ratio of experimental vs. active comparator vs. placebo comparator)
2. Adverse Events will be coded to preferred term and body system using the Medical Dictionary for Regulatory Activities (MedDRA)

Inclusion Criteria (abbreviated)

1. Males or females, age 20 years or above, able and willing to provide written informed consent
2. Knee or Hip OA diagnosed according to American College of Rheumatology guidelines
3. Chronic pain for ≥3 months from OA
4. BP [systolic 90-140 mmHg, diastolic 50-90 mmHg] and pulse rate [resting 40-100 bpm].
5. WOMAC-Pain score in the index joint must be between 4-8 on a 0-10 numerical rating scale
6. Blood chemistry must be within 2x normal range
7. Urinalysis must be within normal limits; minor deviations are acceptable
8. Subjects and their sexual partners must agree to use double barrier contraception during the study period and for 3 months afterward, or be at least one year post- menopause, or provide proof of surgical sterility
9. For prior non-steroidal inflammatory drug (NSAID) users only, the subject has a history of positive therapeutic benefit
10. Subject is willing to limit alcohol intake to 2 or less drinks per day during study and the follow-up period
11. Subjects must be able to read, understand and follow study related documents.

Exclusion Criteria (abbreviated)

1. Use of any analgesics except the study medication or acetaminophen at any time
2. Use of any medications for ongoing chronic symptoms, or psychiatric disorders that could significantly diminish the cognitive ability or cause behavioral changes that would prevent the subject from complying with study procedures.
3. Subject is legally incompetent, or has active psychosis, or significant emotional problems which are sufficient to interfere with the conduct of the study
4. Use of anticoagulants (aspirin, warfarin, heparin, etc.) within 2 weeks of V1
5. Previous history of hypersensitivity or allergy to NSAIDs, COX-2 inhibitors, carbonic anhydrase inhibitors, sulfa drugs, aspirin, or acetaminophen/paracetamol
6. Subjects requiring knee or hip arthroplasty within 2 months of screening or anticipating any need for a surgical procedure on the index joint during the study
7. Diagnosed or treated for active GI ulcer, GI bleeding, ulcerative colitis, or severe renal, hepatic, or coagulant disorder within 6 months prior to randomization
8. History of nasal polyps, bronchospasm, urticaria, or anaphylactic shock
9. Subjects who have had surgery on the affected joint within 6 months prior to the study and subjects with a prosthesis at the index joint
10. Pregnant or breast-feeding, or expecting to conceive within the projected duration of the study
11. Subjects who are currently participating or have participated in other clinical studies within 4 weeks of screening or in any other clinical trial evaluating NSAIDs or COX-2 inhibitors within 6 months of screening
12. Subjects who have received even one dose of rofecoxib or etoricoxib at any time in their life
13. History of congestive heart failure with a status of New York Heart Association II-IV, ischemic heart disease, uncontrolled hypertension, peripheral arterial disease, cerebrovascular disease or subjects who have one of these diseases
14. Current user of recreational or illicit drugs or has had a recent history (1 year) of drug or alcohol abuse or dependence
15. History of neoplastic disease or chemotherapy within 5 years of V1, with the exception of non-metastatic skin cancer that has been completely cured
16. Subjects with gout, pseudogout, inflammatory arthritis, Paget's disease of bone, chronic pain syndrome, fibromyalgia, or another major joint disease
17. Subjects using i.v, i.m., or oral corticosteroids, i.a. steroids or hyaluronic acid injections within 1 month of V1
18. Subjects receiving a Chinese traditional arthritis treatment within 1 week of V1
19. Subjects who are not suitable to participate in the study by the investigator's clinical decision

This medication already got NDA approval in Korea