Effect of orally administered two equal and consecutive doses of proton pump inhibitors, omeprazole, lansoprazole, esomeprazole , rabeprazole and pantoprazole and Histamine 2 receptor antagonists cimetidine, ranitidine,famotidine,nizatidine and lafutidine without and with a prokinetic agents domperidone, metoclopramide and erythromycin on intragastric pH, volume and bile refluxate.