A Phase 2 Randomized Double‑Blind Placebo‑Controlled Study of LY3537031 in Adults with Irritable Bowel Syndrome‑Diarrhea (IBS‑D)

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What is this study about?

The study focuses on adults who have Irritable Bowel Syndrome-Diarrhea, a condition that causes frequent loose stools, abdominal pain, and urgency. The treatment being tested is an injectable medication called Brenipatide, which contains the experimental substance LY3537031. A matching placebo is used for comparison.

The purpose of the study is to determine whether the investigational drug improves symptoms compared with the control. Participants are randomly assigned to receive either the medication or the placebo, and neither the participants nor the study staff know which is given (double‑blind). The drug is administered by a small injection under the skin (subcutaneous) on a regular schedule over several weeks, with follow‑up visits to check health and record daily bowel habits.

During the study, participants keep a simple diary of stool frequency, consistency, and pain, and they attend periodic clinic visits for safety checks, such as brief physical examinations and basic laboratory tests. The overall study period lasts about four months, after which the collected information is used to assess the medication’s effect on the condition.

1 randomization and baseline assessments

after joining, you will be randomly assigned to receive either brenipatide or a matching placebo. the assignment is unknown to you and the study staff.

baseline measurements of your health and irritable bowel syndrome‑diarrhea symptoms will be recorded before the first dose.

2 medication administration

you will self‑administer a subcutaneous injection using a pre‑filled syringe provided by the study.

the injection contains either brenipatide or the placebo; the exact dose is supplied in the syringe as specified by the study protocol.

injections will be given according to the schedule given by the study team, and you will be instructed on how to perform each injection safely.

3 daily symptom diary

each day you will record information about your bowel movements, abdominal discomfort, and any other relevant symptoms in a diary.

the diary entries are used to evaluate your response to the study medication throughout the trial.

4 scheduled follow‑up visits

throughout the treatment period you will attend clinic visits arranged by the study.

during these visits safety checks will be performed, additional syringes may be provided, and any questions about the study procedures can be addressed.

5 primary efficacy assessment (weeks 9–16)

from week 9 through week 16, the daily diary data will be analyzed to determine the percentage of days you experienced a composite clinical response.

this assessment is the main measure used to compare brenipatide with the placebo.

6 final study visit

at the end of the study period you will have a final visit where overall health, safety, and symptom information are reviewed.

any remaining study material will be returned, and the study will be concluded for you.

Who Can Join the Study?

  • You must meet the Rome IV criteria for IBS‑D, which means that more than 25 % of your bowel movements are loose or watery (called Bristol Stool Form Scale types 6 or 7) and less than 25 % are very hard (types 1 or 2).
  • During a 14‑day screening period you will record your symptoms in an electronic diary. Your average worst stomach‑ache rating must be 3 out of 10 or higher on a scale that goes from 0 (no pain) to 10 (worst possible pain).
  • In the same 14‑day screening you need to have at least four days each week when your stool consistency is at least a type 5 on the Bristol Stool Form Scale, and on at least two of those days the stool must be a type 6 or higher.
  • You must not have made any major changes to your usual diet in the four weeks before you start screening.
  • You must be an adult (generally 18 years or older) and can be either male or female.

Who Cannot Join the Study?

  • Having a diagnosis of IBS that is the constipation type, the mixed type, or an unclassified type, as defined by the Rome IV criteria (a set of guidelines doctors use to identify different kinds of IBS).
  • Having a past or present inflammatory or immune‑mediated gastrointestinal disorder, such as Crohn’s disease or ulcerative colitis (conditions where the gut becomes inflamed because the immune system attacks it).
  • Having a known problem with how quickly the stomach empties its contents, called a gastric emptying abnormality (the stomach may be too slow or too fast at moving food into the intestines).

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

Site Name City Country Status
Klinische Forschung Karlsruhe GmbH Karlsruhe Germany
Hospital Universitario De Salamanca Salamanca Spain
Katholieke Universiteit te Leuven Leuven Belgium

Other Sites

Site Name City Country Status
Sint-Lucas General Hospital Brugge Belgium
Az Maria Middelares Gent Gent Belgium
AZ Sint-Lucas & Volkskliniek Gent Belgium
Fbgdjilkng Gcuv Offenbach Am Main Germany
Ksdxwrbrw Fjhslqslg Huxyfih Gmsx Hamburg Germany
Ayvoofg Gpvw Ddc Akytuueeu Bixibauucyijpvx Leipzig Germany
Sddozrbgnwrtmd Mku Duxfvg Dachau Germany
Ckphfgl Gynmx Skzmesin Santiago De Compostela Spain
Hcmhbugv Vojd duocpjsy Barcelona Spain
Hhjhrosq Cdtxwsu Sfe Ckczlf Madrid Spain
Ghjfgxbwaphfxza Aggmoeezx Antwerp Belgium
Cvg Mvtxddooz Liege Belgium
Uvgbrnvknn Ou Apqisdk Edegem Belgium
Uqhslodecvov Zfmpmwttln Gxox Gent Belgium
Higujicb Umtpodctmxlqs Pmyoww Dc Hturjk Dp Mdkhqqzfwsg Majadahonda Spain
Vuwxz Umlvbqdgpiow Buqyrhk Jette Belgium
Asebhhlq Zymfohzbii Daffh Roeselare Belgium
Eab Osixt Suz Aps Clxbmio Shbvtq Centelles Spain
Hnzzftlx Uhqnazxxdaojd Vgznab De Lyp Nlepdm Granada Spain
Hrzpiwze Chcge dxp Sqj Marbella Spain

Want to learn more about this study or check if you can participate? Contact us.

Trial status

Country Status Recruitment Start
Belgium Belgium
Not yet recruiting
20.07.2026
Germany Germany
Not yet recruiting
20.07.2026
Spain Spain
Not yet recruiting
20.07.2026

Trial locations

Investigated Drugs:

Brenipatide is an experimental medication being tested to see if it can help adults with diarrhea‑predominant irritable bowel syndrome (IBS‑D). It is given as a liquid that is injected just under the skin using a pre‑filled syringe. In the study, participants receive this medicine to find out whether it can improve their daily symptoms compared with a placebo.

Irritable bowel syndrome with diarrhea (IBS‑D) – Irritable bowel syndrome with diarrhea (IBS-D) is a functional disorder of the large intestine that causes frequent loose stools and abdominal discomfort. Symptoms often begin in early adulthood and may wax and wane over time. Bowel movements can be urgent and accompanied by cramping, bloating, and a feeling of incomplete emptying. Stress, certain foods, and hormonal changes can trigger flare‑ups. The condition does not cause permanent damage to the intestine, but symptoms may become more frequent if triggers are not managed.

Trial ID:
2025-524973-17-00
Protocol code:
J2S-MC-GZMS
Trial Phase:
Therapeutic exploratory (Phase II)

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