Exploratory, multicenter, open-label study to evaluate the effects of linaclotide in patients with chronic constipation with an insufficient response to magnesium oxide: A study protocol.

Background: Chronic constipation leads to poor quality of life, and treatment remains unsatisfactory for patients. In Japan, magnesium oxide has been commonly used as the first choice of treatment for constipation; however, there are some cases of low satisfaction with magnesium oxide treatment. Linaclotide has recently been used to treat chronic constipation. In this study, we will examine whether linaclotide improves symptoms and quality of life in patients showing insufficient response to magnesium oxide.

Methods: This is an exploratory multicenter open-label study. The target number of patients is 64: 32 patients with and 32 without abdominal symptoms. Patients with chronic idiopathic constipation or irritate bowel syndrome with constipation diagnosed according to the Rome-IV criteria are eligible. Patients prescribed 0.99-2 g/day of magnesium oxide for at least 4 weeks will be included. Those who consent to the study will continue taking magnesium oxide for 2-4 weeks, and defecation will be documented. Patients who meet the criteria will be prescribed linaclotide (0.5 mg) daily for 12 weeks. The primary endpoint is a change in the Japanese version of the Patient Assessment of Constipation Quality of Life (JPAC-QOL) score after 12 weeks of treatment.

Conclusion: This is the first study to investigate the usefulness of linaclotide as a second-line treatment for chronic constipation. We will test the efficacy of treatment of constipation in patients with inadequate response to magnesium oxide.

Trial Registration: This study is registered with the Japan Registry of Clinical Trials (jRCT, jRCTs031200048).