Oxycodone hydrochloride and naloxone hydrochloride dihydrate combined oral prolonged release tablets (OXN PR), is the investigational product to be used in this study. OXN PR is a prolonged release tablet consisting of oxycodone and naloxone in a 2:1 ratio. Due to the local competitive antagonism of the opioid receptor-mediated oxycodone effect by naloxone in the gut, naloxone reduces opioid-associated bowel dysfunction.