The primary objective is to demonstrate that patients 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. The primary objective is to demonstrate that patients taking oxycodone/naloxone prolonged release tablets have improvement in symptoms of constipation compared to subjects taking oxycodone prolonged release tablets alone.

Inclusion Criteria:

• Male or female subjects at least 18 years or older with moderate to severe pain that requires around the clock opioid therapy. Subjects must report constipation caused or aggravated by opioids.

Exclusion Criteria:

• Females who are pregnant or lactating.
• Subjects with evidence of any clinically unstable disease or subjects with evidence of impaired liver/kidney function upon entry into the study.
• Subjects with evidence of significant structural abnormalities of the gastrointestinal tract.