Irritable bowel syndrome with constipation (IBS-C) is a common gastrointestinal (GI) disorder. It’s a type of IBS that affects as many as one-third of people with the condition.

Common symptoms of IBS-C include bloating, discomfort, abdominal pain, and changes in bowel movements and stool. IBS with constipation usually causes hard stools, so difficulty passing stools and infrequent bowel movements are also common.

There’s currently no cure for IBS-C, but with the right treatment plan, symptoms can be managed. Treatments for IBS-C often include lifestyle changes and diet, but medication may be prescribed in some cases.

One of the most recent oral medications approved by the Food and Drug Administration (FDA) for the treatment of IBS-C is tenapanor (Ibsrela). When other medications haven’t helped, ask your doctor about whether tenapanor is right for you.

Tenapanor (Ibsrela) was approved in September 2019 by the FDA to treat IBS-C but wasn’t launched in the United States until a couple of years later.

Ardelyx, the manufacturer of tenapanor, switched gears to target hyperphosphatemia, a condition that causes extra phosphorus in the blood, instead of IBS-C.

Tenapanor (marketed as Xphozah) was intended to help adults with chronic kidney disease control the amount of phosphorus in their blood, especially those who didn’t respond to other therapies and were on dialysis.

The medication worked in the gut to prevent phosphate absorption, specifically blocking the sodium-hydrogen exchanger 3 (NHE3) receptor.

One tablet taken twice daily by mouth was reportedly enough to inhibit phosphorus uptake. Researchers noted that the most common side effect of the medication was diarrhea.

After an FDA review in July 2021 of tenapanor to treat hyperphosphatemia, the medication was pivoted again and launched in April 2022 as the first and only NHE3 inhibitor for the treatment of IBS-C.

Although the launch of the medication was delayed, the science behind the medication remained the same.

It still works in the gut, particularly the small intestine and colon, to block the absorption of certain substances by turning off the sodium-hydrogen exchanger 3 (NHE3) receptor.

While its aim with hyperphosphatemia patients was to stop phosphorus absorption, in people with IBS-C, it inhibits dietary sodium uptake. This results in an increase in water secretion by the intestines.

Elevated water secretion likely played a role in why hyperphosphatemia patients without constipation experienced diarrhea while taking this medication.

Tenapanor triggers an increase in water secretion, which helps relieve the constipation of IBS-C.

More water in the stool elimination process can lead to softer and more frequent bowel movements. This can also help reduce bloating and abdominal pain.

Additionally, tenapanor positively affects visceral hypersensitivity. This condition occurs when your visceral organs — the soft organs residing in your abdomen, pelvis, and chest — are more sensitive and produce feelings of pain and discomfort more easily.

Tenapanor decreases visceral hypersensitivity, reducing pain even if you don’t have a bowel movement.

The FDA mainly used two clinical trials when reviewing tenapanor for the treatment of IBS-C.

In a 2021 clinical trial, 293 participants with IBS-C, ages 18 to 75 years, were given 50 mg of tenapanor twice a day, while another 235 were given a placebo for 26 weeks.

During this time, they assessed symptoms related to:

  • ease, timing, and frequency of bowel movements
  • abdominal pain and discomfort
  • the sensation of complete emptying
  • the need to use rescue medication (such as a laxative)

Those who received tenapanor reported less abdominal pain and having bowel movements more often than the placebo group.

In a 2020 clinical trial, participants with IBS-C were either given 50 mg of tenapanor twice a day or a placebo for 12 weeks. The severity of their symptoms and whether they saw constipation relief was recorded.

After 12 weeks, some people took tenapanor for 4 weeks while others switched to a placebo to evaluate withdrawal symptoms. At the end of the study, more people who took tenapanor reported less constipation and reduced abdominal pain.

Over 1,200 patients participated in the clinical trials. Those who were given tenapanor reported a 30% or greater improvement in their frequency of spontaneous bowel movement and severity of abdominal pain compared to those given the placebo.

Some reported improvements as early as the first week after taking tenapanor twice a day. The most commonly reported symptom was mild-to-moderate diarrhea that often resolved in a week or less.

Tenapanor is only for adults. It’s recommended for those with IBS-C who regularly experience two or more symptoms over at least 3 months, including:

  • the sensation of blockage or failure to completely empty the bowels
  • straining during 25% or more of bowel movements
  • required manual maneuvers to facilitate at least 25% of bowel movements

It’s typically recommended when other treatments — such as stimulant laxatives, osmotic laxatives, or saline laxatives — haven’t improved symptoms.

Tenapanor isn’t a supplemental medication, meaning that it’s not recommended to be used together with other treatment options, such as linaclotide (Linzess).

Additionally, it’s not recommended if you show an indication of mechanical bowel obstruction. The safety of tenapanor (Ibsrela) for pregnant people hasn’t yet been established.

If you’re considering tenapanor (Ibsrela) for IBS-C that’s not responding to other treatments, reach out to your doctor.

Though there’s currently no cure for IBS-C, new research is producing innovative medications, such as tenapanor, that may help manage your symptoms.

For many with IBS-C, medication with lifestyle changes means lasting relief is on the horizon.