Opioid Rotation from Oral Morphine to Oral Oxycodone in Cancer Patients with Intolerable Adverse Effects: An Open-Label Trial

Objective: We prospectively investigated the efficacy of opioid rotation from oral morphine to oral oxycodone in cancer patients who had difficulty in continuing oral morphine treatment because of inadequate analgesia and/or intolerable side effects. Methods: Twenty-seven patients were enrolled and 25 were evaluated. The rate of patients who achieved adequate pain control, which provided an indication of treatment success, was evaluated as primary endpoint. The acceptability and pharmacokinetics of oxycodone were evaluated in addition to the assessment of analgesic efficacy and safety during the study period. Results: In spite of intense pain, the morphine daily dose could not be increased in most patients before the study because of intolerable side effects. However, switching to oral oxy-codone allowed 1.7-fold increase as morphine equivalent dose. Consequently, 84.0 % (21/ 25) of patients achieved adequate pain control. By the end of the study, all patients excep