The primary objective of this study is to demonstrate that subjects with moderate to severe non-malignant pain taking oxycodone/naloxone prolonged release tablets have improvement in symptoms of constipation compared to subjects taking oxycodone prolonged release tablets alone.

Patients with a documented history of moderate to severe non-malignant pain that require around the clock opioid therapy will be randomised to an oxycodone or an oxycodone-naloxone treatment arm to assess the safety and efficacy of oxycodone/naloxone prolonged release compared to oxycodone prolonged-release in relieving opioid-related constipation.

Inclusion Criteria:

• Male or female subjects at lest 18 years or older with pain.
• Subjects must report constipation caused or aggravated by opioids.

Exclusion Criteria:

• Females who are pregnant or lactating.
• Subjects with evidence of significant structural abnormalities of the gastrointestinal (GI) tract (e.g. bowel obstruction, strictures).