The FDA has approved tenapanor (Ibsrela, Ardelyx) as a treatment for irritable bowel syndrome with constipation (IBS-C) among adults.
Tenapanor, a 50-mg, twice-daily pill, is a minimally absorbed small molecule that acts locally in the gastrointestinal tract to inhibit the sodium-hydrogen exchanger NHE3, resulting in an increase in bowel movements and a decrease in abdominal pain. It is a new approach to managing a difficult-to-treat condition that affects more than 11 million Americans.
In two randomized, double-blind, placebo-controlled phase 3 trials, the primary endpoint was the proportion of patients who were responders during the 12-week treatment period. A responder experienced at least a 30% reduction in the weekly average abdominal pain score compared with baseline and an increase of at least one complete spontaneous bowel movement in weekly average from baseline, in the same week, for at least six of the first 12 treatment weeks. Tenapanor, compared with placebo, met this goal in both Trial 1 (37% versus 24%) and Trial 2 (27% versus 19%).
In both studies, the most common adverse event was diarrhea.
Tenapanor carries a boxed warning noting that it is contraindicated in patients less than 6 years of age. Health care providers should avoid use of tenapanor in patients 6 years to less than 12 years of age, and safety and effectiveness have not been established in pediatric patients less than 18 years of age.
Tenapanor represents the first-ever product approval for Ardelyx, which expects to recruit a marketing partner. The drug is also in development as a treatment for hyperphosphatemia among chronic kidney disease patients on dialysis, with an application expected in 2020.
Source: Ardelyx, September 12, 2019