Active Drug Comparative, Multi-center, phase3 Clinical Study to Evaluate the Efficacy and Safety of PG201 in Osteoarthritis Patients

Inclusion Criteria: 1. Patients ≥40 and ≤ 80years of age. 2. Patients who meet the American College of Rheumatology clinical plus radiographic classification criteria for idiopathic osteoarthritis of the knee, which are defined as follow: a patient who had knee pain and radiographically diagnosed osteophytes and met at least one of the followings. * Age\> 50 years. * Morning stiffness for less than 30 minutes. * Crepitus during movement of the weight-bearing knee. 3. Patients with symptomatic primary osteoarthritis of the knee at least in the last 3 months prior to screening. 4. Patients who received Nonsteroidal antiinflammatory drugs (NSAIDs)/Cyclooxygenase-2 inhibitor for the treatment of arthritis of the knee for at least 5 days a week during 4 weeks prior to screening. 5. Patients who had a score of 100mm pain VAS ≤80 mm at screening. 6. Patients who had a score of 100mm pain VAS ≥50 mm at baseline. 7. Patients should be able and willing to provide the written informed consent. Exclusion Criteria: 1. Patients with a history of surgery or arthroscopy of the study joint within the previous 6 months. 2. Patients with trauma of study joint within the previous 12 months. 3. Patients with symptomatic hip osteoarthritis, other condition that would interfere with study assessments. 4. Patients with any other type of arthritis, active malignancies or any active GI, cardiovascular, renal, hepatic, neurologic, or psychiatric disease. 5. Patients with a known hypersensitivity or intolerance to Nonsteroidal antiinflammatory drugs (NSAIDs), aspirin or Cyclooxygenase-2 inhibitor. 6. Patients with uncontrollable hypertension. 7. Patients with any of creatinine, bilirubin, Alanine aminotransferase or Aspartate aminotransferase \> 1.5 times the Upper Lange of normal at screening. 8. Patients with a history of drug or alcohol abuse.