Rationale and design of a multicenter, double-blinded, randomized, placebo-controlled trial to investigate the effects of naldemedine on opioid-induced constipation for patients with cancer pain: A study protocol

Background: It is unclear which laxatives are appropriate to prevent opioid-induced constipation (OIC). This study will evaluate whether prophylactic use of naldemedine prevents OIC in patients with cancer who start opioid administration. Methods: This study is a multicenter, double-blinded, randomized, placebo-controlled trial. Patients who meet the eligibility criteria and give consent will be randomly assigned to the naldemedine or placebo group. Both groups will take each drug once a day after breakfast for 14 days. Results: The primary endpoint is the proportion of patients with a Bowel Function Index of less than 28.8 on Day 14. The secondary endpoints include assessment scales of the impact of constipation on comprehensive quality of life. Conclusions: This is the first study proposed to assess the superiority of naldemedine over placebo in the prevention of OIC. If naldemedine is found to be effective in reducing OIC compared with the placebo, it will be regarded as a new standard for OIC prophylaxis at opioid initiation. Trial registration: jRCT identifier: jRCTs031200397. Registered March 5, 2021, https://rctportal.niph.go.jp/en/detail?trial_id=jRCTs031200397.