Comparison Study of a New Combination of 2 Marketed Medications (Esomeprazole and Naprosyn) Versus Naprosyn Alone

Inclusion Criteria: * Subjects must have a body weight greater than 50 kg and BMI within the range 18-30(inclusive). * Subjects must be in good health, as assessed during pre-study medical examination and by review of screening results * Subjects must understand the procedures involved and agree to participate in the study by giving fully informed, written consent Exclusion Criteria: * Significant intercurrent disease of any type, in particular liver, kidney, cardiovascular disease, any form of diabetes or significant gastrointestinal disorder which could affect drug absorption, or any history of gastric or duodenal ulceration. * Ingestion of any naproxen, omeprazole, esomeprazole or related drugs prior to the recruitment interview, such that these drugs will have been ingested in the 4 weeks prior to the day set for the first Period 1 dose