Naproxen/esomeprazole is a fixed-dose combination of the NSAID naproxen and the proton pump inhibitor esomeprazole. In two well designed, 12-week studies, naproxen/esomeprazole fixed-dose combination was noninferior to celecoxib in treating the signs and symptoms of disease in patients with osteoarthritis of the knee, as assessed by the mean change from baseline in Western Ontario and McMaster Universities Osteoarthritis Index pain and function scores and Patient Global Assessment scores (coprimary endpoints). Two other studies showed that the cumulative incidence of gastric ulcers (primary efficacy measure) was significantly lower with naproxen/esomeprazole than with enteric-coated naproxen alone during up to 6 months' therapy in patients with osteoarthritis, rheumatoid arthritis, ankylosing spondylitis or any other condition requiring daily NSAID therapy. The fixed-dose combination was generally well tolerated in these studies, with an upper gastrointestinal tolerability profile generally better than that of naproxen and similar to that of celecoxib.