Safety and efficacy of the sodium-glucose cotransporter 1 inhibitor mizagliflozin for functional constipation: a randomised, placebo-controlled, double-blind phase 2 trial

Background: Mizagliflozin is a novel oral sodium-glucose cotransporter 1 (SGLT1) inhibitor that increases luminal glucose and water. This study assessed the efficacy and safety of mizagliflozin in patients with functional constipation.

Methods: In this multicentre, randomised, double-blind phase 2 trial at 32 hospitals and community outpatient clinics in Japan, we enrolled patients with functional constipation or constipation-predominant irritable bowel syndrome, aged 20 years or older. Patients were randomly assigned (1:1:1), by use of an independent centralised registration system and dynamic allocation method, to receive mizagliflozin 5 mg, mizagliflozin 10 mg, or placebo, orally once daily for 4 weeks. Patients, investigators, staff, and the sponsor were blinded to the group assignments. The primary outcome was the change from baseline in the number of spontaneous bowel movements per week after 1 week. Efficacy analysis was done in all patients except those who deviated from good clinical practice, did not receive at least one dose of the study drug, withdrew before starting treatment, were ineligible, or for whom the primary outcome could not be assessed, and safety was assessed in all patients except those who deviated from good clinical practice, who did not receive the study drug, or who withdrew before receiving treatment. This trial is registered with ClinicalTrials.gov, number NCT02281630, and is completed.

Findings: Between Oct 15, 2014, and March 7, 2015, 258 patients with functional constipation were randomly assigned: 86 patients per group. Two patients from the placebo group and three from the 10 mg mizagliflozin group were excluded because the primary outcome could not be assessed, and one patient from the 5 mg mizagliflozin group was excluded for not receiving the study drug; therefore 84 patients in the placebo group, 85 in the 5 mg mizagliflozin group, and 83 in the 10 mg mizagliflozin group were included in the full analysis population. Mean change from baseline in the number of spontaneous bowel movements per week after 1 week with mizagliflozin 5 mg (3·85 [SD 3·96]) and mizagliflozin 10 mg (5·85 [6·01]) was significantly greater than those in the placebo group (1·80 [1·80]; p<0·0001 for both comparisons). The most common adverse events were nasopharyngitis (one [1%] of 86 patients in the placebo group, seven [8%] of 85 on mizagliflozin 5 mg, and five [6%] of 86 on mizagliflozin 10 mg), diarrhoea (none on placebo, four [5%] patients on mizagliflozin 5 mg, and eight [9%] on mizagliflozin 10 mg), and abdominal distention (three [3%] on placebo, four [5%] on mizagliflozin 5 mg, and seven [8%] on mizagliflozin 10 mg). Only diarrhoea and abdominal distention were deemed to be related to mizagliflozin treatment, whereas nasophanyngitis might not be related to mizagliflozin treatment, on the basis of clinical evaluation.

Interpretation: The SGLT1 inhibitor mizagliflozin showed favourable efficacy and tolerability at 5 mg and 10 mg doses in patients with functional constipation, providing a potential alternative therapy to available drugs.

Funding: Kissei Pharmaceutical.