FDA Approves Tenapanor to Treat Irritable Bowel Syndrome with Constipation

A new drug to treat irritable bowel syndrome with constipation (IBS-C) called tenapanor (IBSRELA) will soon be on the market.

The US Food and Drug Administration gave the green light to Ardelyx for the 50 mg, twice daily oral pill to increase bowel movements and decrease abdominal pain for IBS-C patients.

"IBSRELA has the potential to provide IBS-C patients and their doctors with a novel mechanism and an innovative approach to managing IBS-C, a highly burdensome and difficult-to-treat condition affecting more than 11 million people in the United States," Mike Raab, president and chief executive officer of Ardelyx, said in a statement. "This approval is an extremely important and rewarding milestone for Ardelyx, and represents the culmination of years of dedication to advancing our discoveries and medicines in an effective and rigorous manner.”

The drug was tested during a pair of randomized, double-blind, placebo-controlled trials that were identical through 12 weeks of treatment, with 1 of the trials continuing for an additional 14 weeks, and the other including a 4-week randomized withdrawal period.

The primary endpoint for both trials was the proportion of patients who saw at least a 30% reduction in the weekly average abdoiminal pain score compared with baseline and an increase of at least 1 complete spontaneous bowel movement in weekly average from baseline, in the same week, for at least 6 of the first 12 weeks of treatment.

In both phase 3 trials, the drug met the primary endpoint as compared to the treatment group that only received placebo (Trial 1: 37% versus 24%, IBSRELA versus placebo, respectively. Trial 2: 27% versus 19% IBSRELA versus placebo, respectively).

The proportion of responders for 9 out of the first 12 weeks, including at least 3 of the last 4 weeks, was greater in tenapanor-treated patients compared to placebo-treated patients.

The most common adverse event in both trials was diarrhea (16% with IBSRELA vs 4% with placebo in Trial 1; and 15% with IBSRELA vs 2% with placebo in Trial 2), with severe diarrhea reported in 2.5% of IBSRELA-treated patients compared to .2% on placebo‑treated patients during the 26 weeks of Trial 1 and the 12 weeks of Trial 2.

Raab said the next step for Ardelyx will be to collaborate with a commercial partner to market the new drug.

He also explained some of the future plans for the biopharmaceutical company.

"With the approval of IBSRELA for IBS-C, along with the successful completion of our AMPLIFY trial in hyperphosphatemia, we've delivered on two major corporate milestones in the last two weeks due to flawless execution by the remarkable and talented team at Ardelyx,” Raab said. “With these milestones accomplished, and the PHREEDOM trial reading out in Q4, I have great confidence that we are well positioned to file our NDA for hyperphosphatemia next year with potential approval and launch in 2021.”