A drug known as tenapanor appears to help relieve symptoms in patients with irritable bowel syndrome (IBS). Findings from a Phase IIb clinical trial were presented at the Digestive Disease Week 2015 conference Washington, D.C., May 16–19, and reported in the journal Gastroenterology.
Irritable bowel syndrome is a disorder that affects the large intestine, or colon. Its symptoms include cramping, abdominal pain, bloating, constipation, and diarrhea. IBS is common, affecting up to 20 percent—one in five—of adults in the United States. More women suffer from IBS than men. There is currently no known cause of IBS, but, according to research, it’s probably the result of sensitivity of the large intestine to certain foods and stress. Effective treatments for IBS are very much needed.
Tenapanor works by blocking the action of a protein that regulates sodium levels in the kidneys and intestines. As a result, the amount of sodium that the body absorbs from food is limited. In early studies, tenapanor has appeared promising in the treatment of IBS.
In this recent study of tenapanor, researchers evaluated the drug’s safety and effectiveness in 356 patients with IBS. Over three months, participants were given three different dose levels of tenapanor (5, 20, or 50 mg) or placebo. After three months of treatment, the researchers followed the patients for one month.
The majority of patients (61%) who received tenapanor at 50 mg two times per day responded to treatment. This was almost twice the response rate as the placebo patients, who had only a 34% response rate. Specifically, of the patients receiving tenapanor at 50 mg, 66% had at least a 30% decrease in abdominal pain, whereas about 20% less of the placebo patients (48%) had a decrease in abdominal pain. On 50 mg of tenapanor, patients also had significant improvements in abdominal discomfort, bloating, straining, and stool consistency.
The largest dose of tenapanor (50 mg twice daily) was the most effective. Patients responded to the smaller doses—5 and 20 mg—but not to a significant extent.
Patients tolerated tenapanor well. Side effects that did occur included diarrhea and urinary tract infection. Few patients (less than 5%), however, had to stop taking tenapanor due to side effects.
According to this study, tenapanor may offer a safe and effective treatment option for people who suffer from IBS. These promising findings justify further research of tenapanor in IBS.
Reference: Chey WD, Lembo A, Phillips JA, Rosenbaum DP. Efficacy and Safety of Tenapanor in Patients With Constipation Predominant Irritable Bowel Syndrome: A 12-Week, Double-Blind, Placebo-Controlled, Randomized Phase 2B Trial. Gastroenterology. April 2015; Volume 148, Issue 4, Supplement 1, Pages S-191–S-192.