Determine the Safety and Efficacy of Oxy/Nal Tablets Compared to Oxy PR in Subjects With Cancer Pain

Inclusion Criteria Males \& females, at least 18 years or older with a diagnosis of cancer. Females less than one year post-menopausal must have a negative urine pregnancy test recorded prior to the first dose of study medication, be non-lactating, \& willing to use adequate \& highly effective method of contraception throughout the study. Highly effective methods of birth control are defined as those which result in a low failure rate (i.e. less than 1% per year) when used consistently correctly such as sterilisation, implants, injectables, combined oral contraceptives, some IUDs (hormonal), sexual abstinence or vasectomised partner. Subjects who are receiving WHO step II or Step III analgesic medication who have constipation induced, or worsened by their opioid medication, as shown by 1. the subject's medical need of regular intake of laxatives to have at least 3 bowel evacuations per week, or having less than 3 bowel evacuations when not taking a laxative, respectively. 2. the subject's self-assessment that their constipation was induced or worsened by their current pre-study opioid medication. Documented history of moderate to severe, chronic cancer pain that requires around the-clock opioid therapy (starting dose of oxycodone PR between 20-80 mg/day) \& are likely to benefit from WHO step III opioid therapy for the duration of the study. Subjects must be willing to discontinue their current opioid analgesic routine. Opioid medication continue at a stable or nearly stable dose in the investigator's opinion during the treatment. Subjects are willing to discontinue pre study laxative medication \& take study specific laxative medication. Subjects taking daily fibre supplementation or bulking agents are eligible if they can be maintained on a stable dose \& regimen throughout the study, \& in the investigators opinion are willing \& able to maintain adequate hydration. Subjects willing \& able (e.g. mental \& physical condition) to participate in all aspects of the study, including use of medication, completion of subjective evaluations, attending scheduled clinic visits, completing telephone contacts, \& compliance with protocol requirements as evidenced by providing written, informed consent. Subjects already taking non-opioid analgesics \& all other concomitant medications (including those for the treatment of depression) are eligible to take part in the study. However, all concomitant medications that are considered necessary for the subject's welfare…