Novel Pilot Study to Treat Symptoms of IBS With Diarrhea Using Combination Therapy of a Low-FODMAP Diet and a Neuromodulator

NCT ID: NCT06684470

Last Updated: 2025-12-18

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

RECRUITING

Clinical Phase

EARLY_PHASE1

Total Enrollment

20 participants

Study Classification

INTERVENTIONAL

Study Start Date

2024-12-19

Study Completion Date

2026-12-19

Brief Summary

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The purpose of this research is to study the added benefit of treating IBS symptoms with a medication called mirtazapine in treating IBS symptoms when paired with a low-FODMAP diet compared to a low-FODMAP diet alone. FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. These are short-chain carbohydrates that can cause digestive distress in some people.

You have been asked to take part in this research because you have symptoms of diarrhea-predominant irritable bowel syndrome that may respond to treatment with a combination of a medication called mirtazapine and a low-FODMAP diet.

Detailed Description

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We hypothesize that adult patients with IBS-D treated with a combination of a low FODMAP diet and mirtazapine will have a greater improvement in global IBS symptoms including abdominal pain and diarrhea in addition to improved quality of life compared to those treated with a low-FODMAP diet only. Global improvement in IBS symptoms will be evaluated using the validated IBS-SSS questionnaire. We will evaluate changes in quality of life using a validated IBS-QoL questionnaire. We will assess the improvement in abdominal pain using a numerical rating system and assess improvements in diarrhea using the Bristol stool form scale. We will assess responses to bloating using a Mayo bloating questionnaire forms. We will assess improvement in diarrhea using the Bristol stool form scale.

Improvement in anxiety and any other descriptive information as provided by patients including patients reporting impression of overall severity of symptoms at the beginning, middle, and end of study.

Irritable bowel syndrome (IBS) is a common gastrointestinal (GI) disorder that affects up to 10% of the United States adult population. IBS is characterized by recurrent abdominal pain and altered bowel habits, diagnosed using the Rome IV criteria. Approximately one-third of all IBS patients are classified as having IBS with diarrhea (IBS-D), which has no validated treatment algorithm. The American College of Gastroenterology IBS guideline recommends the low-FODMAP (fermentable oligo-, di-, monosaccharide, and polyol) diet as a safe and modestly effective treatment. An analysis of 7 randomized, controlled trials found that the low-FODMAP diet was associated with an improvement in global IBS symptoms. However, despite following the low-FODMAP diet, many patients have persistent abdominal pain, which can be difficult to treat. The mechanisms underlying chronic abdominal pain in patients with IBS are unknown, although visceral and central hypersensitivity are thought to play a role. No medication is FDA-approved for the treatment of abdominal pain in IBS. Mirtazapine is an atypical antidepressant that acts on several classes of receptors. In a small open-label study mirtazapine improved IBS-D symptoms, including abdominal pain.

Conditions

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IBS - Irritable Bowel Syndrome Diarrhea

Keywords

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Diarrhea IBS Irritable Bowel Syndrome

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

PARALLEL

Primary Study Purpose

TREATMENT

Blinding Strategy

DOUBLE

Participants Investigators

Study Groups

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Mirtazapine Group

Subjects will present at Mayo Clinic through a doctor's appointment and a diagnosis of irritable bowel syndrome will be receiving mirtazapine by pill form.

Group Type EXPERIMENTAL

Mirtazapine

Intervention Type DRUG

mirtazapine will be told to use 1 pill 1 hour before bedtime for the first week (7.5 mg po q.h.s.), 2 pills before bedtime during the second week of therapy (15 mg po q.h.s.), 3 pills (22.5 mg po q.h.s.) 1 hour before bedtime for the third week, and 4 pills (30 mg po q.h.s.) 1 hour prior to bedtime for the remainder of the study.

Placebo Group

Subjects will present at Mayo Clinic through a doctor's appointment and a diagnosis of irritable bowel syndrome will be receiving placebo by pill form.

Group Type PLACEBO_COMPARATOR

Placebo

Intervention Type OTHER

Placebo will be told to use 1 pill 1 hour before bedtime for the first week (7.5 mg po q.h.s.), 2 pills before bedtime during the second week of therapy (15 mg po q.h.s.), 3 pills (22.5 mg po q.h.s.) 1 hour before bedtime for the third week, and 4 pills (30 mg po q.h.s.) 1 hour prior to bedtime for the remainder of the study.

Interventions

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Mirtazapine

mirtazapine will be told to use 1 pill 1 hour before bedtime for the first week (7.5 mg po q.h.s.), 2 pills before bedtime during the second week of therapy (15 mg po q.h.s.), 3 pills (22.5 mg po q.h.s.) 1 hour before bedtime for the third week, and 4 pills (30 mg po q.h.s.) 1 hour prior to bedtime for the remainder of the study.

Intervention Type DRUG

Placebo

Placebo will be told to use 1 pill 1 hour before bedtime for the first week (7.5 mg po q.h.s.), 2 pills before bedtime during the second week of therapy (15 mg po q.h.s.), 3 pills (22.5 mg po q.h.s.) 1 hour before bedtime for the third week, and 4 pills (30 mg po q.h.s.) 1 hour prior to bedtime for the remainder of the study.

Intervention Type OTHER

Other Intervention Names

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Remeron

Eligibility Criteria

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Inclusion Criteria

* Adults (ages 18-70)
* Score of \>175 on the IBS-SSS questionnaire
* Must meet Rome IV criteria for IBS-D
* If subject is of reproductive capability a negative urine pregnancy test must be available prior to entering the study
* Ability to understand study procedures and to comply with them for the entire length of the study

Exclusion Criteria

* Score of \< 175 on the IBS-SSS
* Prior diagnoses of: known celiac disease, small intestinal bacterial overgrowth, inflammatory bowel disease, or microscopic colitis
* Ongoing significant anxiety or depression
* A history of a known side effect to mirtazapine
* Prior treatment with a low FODMAP diet or mirtazapine without clinical benefit
* Active alcohol or drug abuse
* Inability to read or understand the consent form
* Any other medical or psychological reason that would prevent active participation in a research study
* Pregnant females
Minimum Eligible Age

18 Years

Maximum Eligible Age

70 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

No

Sponsors

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Mayo Clinic

OTHER

Sponsor Role lead

Responsible Party

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Brian Lacy

Principal Investigator

Responsibility Role PRINCIPAL_INVESTIGATOR

Principal Investigators

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Brian E Lacy, MD

Role: PRINCIPAL_INVESTIGATOR

Mayo Clinic

Locations

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Mayo Clinic

Jacksonville, Florida, United States

Site Status RECRUITING

Countries

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United States

Central Contacts

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Jessica C Petrov, MD

Role: CONTACT

Phone: 904-953-2000

Email: [email protected]

Facility Contacts

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Jessica C Petrov, M.D.

Role: primary

Other Identifiers

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23-011874

Identifier Type: -

Identifier Source: org_study_id