ENhANCE trial protocol: A multi-centre, randomised, phase IV trial comparing the efficacy of oxycodone/naloxone prolonged release (OXN PR) versus oxycodone prolonged release (Oxy PR) tablets in patients with advanced cancer.

Oxycodone is a frequently used opioid in cancer. Opioid-induced constipation (OIC) is common. Oxycodone/Naloxone Prolonged Release (OXN PR) contains naloxone, which mitigates OIC. Trials have either focused on non-cancer pain, or conducted before significant experience of using OXN PR. This trial aims to: demonstrate (1) analgesic equivalence between OXN PR and Oxycodone Prolonged Release (Oxy PR), and (2) superiority of constipation outcomes in OXN PR compared to Oxy PR in cancer pain. Unlike other trials, it will only include patients with at least moderate pain scores (≥4/10), allow usual laxatives, and exclude potential liver dysfunction.