Tenapanor 50 mg has demonstrated efficacy, tolerability, and safety in treating constipation-predominant irritable bowel syndrome (IBS-C), according to a study recently published in The American Journal of Gastroenterology. 

This double-blind, placebo-controlled phase 3 study included 629 participants, 606 of whom were randomly assigned to 12 weeks of either tenapanor 50 mg twice daily (n=307) or placebo twice daily (n=299). This was followed by 4 weeks of randomized withdrawal, in which the placebo group received tenapanor and the tenapanor group received either placebo or tenapanor. This study’s primary combined efficacy variable was a reduction of at least 30% from baseline in average weekly worst abdominal pain and increased incidence of at least 1 complete spontaneous bowel movement per week, with both in the same week and occurring for at least 6 weeks of the 12-week trial. Safety assessments accounted for adverse events, vital signs, electrocardiograms, laboratory tests, and physical exams. A Cochran–Mantel–Haenszel test was used to analyze efficacy variables.

Of the 606 participants included in the intention-to-treat set, 261 in the tenapanor group and 272 in the placebo group completed 12 weeks of treatment. Among them, significantly more participants in the tenapanor group (27.0%) met the primary endpoint than in the placebo group (18.7%; P =.020); additionally, the tenapanor group had a significantly higher proportion of participants with improved abdominal pain response than the placebo group (44.0% vs 33.1%; P =.008). Rescue medication use was also lower in the tenapanor group compared with placebo (35.2% vs 44.8%; P =.015). The only adverse event reported by ≥2.0% of the tenapanor group, and more frequently than in the placebo group, was diarrhea, which was reported by 14.6% (n=45) of the tanapanor group vs 1.7% (n=5) of the placebo group; this adverse event resulted in study drug discontinuation among 20 participants.

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Limitations to the study findings include the need for longer trial periods to test long-term effects, a prevalence of white women in the study group, and a rate of adherence that is double what would be expected to occur in clinical practice.


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The study researchers concluded that tenapanor has a “unique mechanism of action, positive impact on key symptoms and satisfaction measures, and acceptable safety profile,” thereby potentially making it “an exciting new treatment option for patients with IBS-C.”

Disclosure: This clinical trial was supported by Ardelyx. Please see the original reference for a full list of authors’ disclosures.

Reference

Chey WD, Lembo AJ, Rosenbaum DP. Efficacy of tenapanor in treating patients with irritable bowel syndrome with constipation: a 12-week, placebo-controlled phase 3 trial (T3MPO-1) [published online January 13, 2020]. Am J Gastroenterol. doi: 10.14309/ajg.0000000000000516