The study will be randomized, double blind, placebo and active control, a 3-way, 3-period crossover design, where each of the estimated 50 enrolled patients will receive alternately (i) NEO6860 (500 mg bid), (ii) placebo and (iii) Naproxen (500 mg bid). To ensure blinding, double dummy techniques will be used, so that at each period, patient will receive an oral liquid suspension (NEO6860 or its placebo) and one capsule (naproxen or its placebo).