Abdominal Symptom Improvement during Clinical Trials of Tenapanor in Patients with Irritable Bowel Syndrome with Constipation: A Post Hoc Analysis

INTRODUCTION:This post hoc analysis evaluated the efficacy of tenapanor on abdominal symptoms in patients with irritable bowel syndrome with constipation. Abdominal symptoms assessed included pain, discomfort, bloating, cramping, and fullness.METHODS:The abdominal symptom data were pooled from 3 randomized controlled trials (NCT01923428, T3MPO-1 [NCT02621892], and T3MPO-2 [NCT02686138]). Weekly scores were calculated for each abdominal symptom, and the Abdominal Score (AS) was derived as the average of weekly scores for abdominal pain, discomfort, and bloating. The overall change from baseline during the 12 weeks was assessed for each symptom weekly score and the AS. The AS 6/12-week and 9/12-week response rates (AS improvement of ≥2 points for ≥6/12- or ≥9/12-week) were also evaluated. The association of weekly AS response status (reduction of ≥30%) with weekly complete spontaneous bowel movement (CSBM) status (=0 and >0) was assessed.RESULTS:Among 1,372 patients (684 tenapanor [50 mg twice a day] and 688 placebo), the least squares mean change from baseline in AS was -2.66 for tenapanor vs -2.09 for placebo (P < 0.0001). The 6/12-week AS response rate was 44.4% for tenapanor vs 32.4% for placebo (P < 0.0001), and for 9/12-week AS, 30.6% for tenapanor vs 20.5% for placebo (P < 0.0001). A significant association between weekly CSBM status and weekly AS response status was observed each week (P < 0.0001), with a greater proportion achieving an AS reduction in patients with >0 CSBMs in a week.DISCUSSION:Tenapanor significantly reduced abdominal symptoms in patients with irritable bowel syndrome with constipation, particularly pain, discomfort, and bloating measured by AS, compared with placebo.