Naxozol is a combination product of naproxen, a non-steroidal anti-inflammatory drug (NSAID) and esomeprazole, a proton pump inhibitor which is designed to improve symptoms and reduce risk of gastric ulcers in patients at risk of developing NSAID-associated gastric ulcers in the treatment of osteoarthritis, rheumatoid arthritis, and ankylosing spondylitis. The purpose of this study is to investigate whether naxozol protects the gastrointestinal tract effectively compared to celecoxib, a COX-2 inhibitor.

A total of 10 orthopedic investigators will participate in this study. The effectiveness in gastro-protection of study drug will be assessed by Leeds Dyspepsia Questionnaire (LDQ). The orthopedic investigators will be trained with this questionnaire administration by an expert gastroenterologist prior to starting this study.

Inclusion Criteria:

• Koreans given informed consent
• Patients who have ability of reading comprehension and completing questionnaires (EQ-5D and VAS)and have willingness to follow-up 12 weeks
• Patients with osteoarthritis symptoms confirmed by his/her medical history and with pain-VAS of 40 and more

Exclusion Criteria:

• Patients who participate into other interventional study or had participated within 30 days before screening
• Alcohol or drug abuse within 6 months or alcohol consumption of 21 units and more in a week
• Peptic ulcers accompanied with a complication such as bleeding, perforation, penetration or gastric outlet obstruction within 5 years, or a history of active peptic ulcer or peptic ulcer without a complication within 6 months at screening
• Patients who are known with Helicobacter pylori infection but have not received any bacteriostatic treatment
• Known gastroesophageal reflux disease (GERD)
• Any following joint diseases which may significant effect to the efficacy and safety assessments: septic arthritis, inflammatory joint arthritis such as rheumatoid arthritis, gout, recurrent pseudo-pain, Paget's disease, joint fracture, joint ochronosis, acromegaly, hematochromatosis, Wilson's disease, primary osteochondrosis, Ehlers Danlos Syndrome, or other collagen genetic disorder
• Patients who are scheduled admissions to hospital for elective surgery during this study
• History of gastrointestinal cancer
• Gastrointestinal disorders related to drug malabsorption
• Gastrointestinal bleeding, cerebral bleeding, other bleeding disorders, or severe hematological disorders
• Clinically significant diseases such as moderate or severe liver diseases (Child Pough Class II or more), severe heart failure or a history of coronary artery bypass graft (CABG), severe kidney diseases (CrCl<30ml/min)
• Know allergy experiences with any ingredient of study drugs or with other NASIDs or protocol pump inhibitors (PPIs)
• Patients who had had a joint surgery for osteoarthritis within 1 year
• Women of childbearing potential who do not agree with clinically appropriate contraception during this study